Troubleshooting guide

Specialty and Effect Inks

Metallics, pearls, fluorescents, colour-change, glitter, drip-off, raised crystal, haptic sand, soft touch and cold foil on press.

Uniform Industries · Greater Noida, India · ufindustries.com
Figures are typical for the class and carry their test method. The values that govern a supply are those on the Technical Data Sheet for the grade.

Before you start

How to use this guide

Work down the page. Cheap checks before expensive ones, and measure before you change anything.

Judge an effect against the retained physical sample at the agreed viewing geometry; a metallic, a pearl or a fluorescent cannot be settled by one 45/0 spectrophotometer reading or by a screen proof. Where a number is required, record the instrument geometry and the measurement mode with it, because a fluorescent read UV-included and UV-cut gives two different answers and a metallic read at one aspecular angle gives none of the others.
Weigh the film before you change anything, and know what the weighing can resolve. On heavy board a 2 g/m2 film is under 1 % of the weight on the balance while the board's own basis weight varies by 1 to 2 %, so use areas cut side by side on the same sheet, a piece weighed before and after printing, or consumption per 1 000 sheets as the cross-check. Most effect faults are still film weight faults wearing another name.
Treat cure at the surface and cure at depth as two separate questions; a heavy effect film, and any UV metallic, can fail either one and the two remedies pull in opposite directions.
Flake and capsule pigments are physical structures, so anything that shears, filters, over-grinds or over-pumps them destroys the effect permanently and no amount of extra ink brings it back. Bead and microsphere coatings are the opposite case: they settle and have to be kept moving, at low shear. Decide which family the material belongs to before you touch the circulation.
Change one variable at a time and log the gel dose, the full dose, the peak irradiance, the film weight, the speed and the stock temperature with it; on effect work the press settings are part of the specification, not an operator preference.
Adhesion, bond, crease, seal and slip belong to the pack and not to the ink, so qualify them on the customer's own board or film, in the finished construction, 24 h after the run and conditioned at 23 C and 50 % RH.
State what the ink is formulated to, never what the pack achieves. Formulation statements only, with migration assessed on the finished pack on request. Raise food, pharmaceutical and toy packs at quotation rather than after the job is booked, because heavy UV films, metallic pigments, glitter and microspheres are the hardest cases for set-off and photoinitiator migration, and some effects are not available on that pack at all.

Specialty and Effect InksHow to use this guide

The process

What happens, in order, and the one variable held at each step.

The process

What is controlled at each step

Specialty and Effect InksThe process

Control variables

What to hold, and how to measure it

Variable	Target	How it is measured	How it drifts
Effect film weight	1.5 to 2.5 g/m2 metallic offset; 3 to 5 g/m2 aqueous soft touch; 6 to 10 g/m2 UV soft touch and haptic; 4 to 8 g/m2 UV gloss flood; 1.5 to 3.0 g/m2 drip-off primer and cold foil adhesive; 30 to 80 g/m2 screen structure coating. Take the window from the grade's data sheet and record the weight the sample was made at, since a feel and an effect are specified at a weight and not at a chemistry.	Gravimetric on matched printed and unprinted areas cut side by side on the same sheet, four place balance, cross-checked against consumption per 1 000 sheets or per 1 000 m divided by the printed area	The direction depends on the feed system, so state which one you are on. Anilox or chamber fed, which is flexo, the coater and the cold foil adhesive: as the pan warms and viscosity falls, cell release improves and the applied weight rises. Roller train and duct fed, which is sheet-fed offset ink and a drip-off primer run through an inking unit: the direction is not fixed and should not be assumed, because a warmer, softer ink flows more freely past the duct key and delivers more, while a long, low body ink splits thinner at the nips and lays down less; which of the two wins is a property of that unit and that ink. Establish it once by weighing the film at two recorded duct temperatures and put the answer on the job record. Both feed systems lose weight as an anilox packs or a mesh blinds. Record pan or duct temperature with every film weight so the direction is measured and not guessed.
Coating or ink viscosity	As stated per grade. Flexo press grades 16 to 22 s; coatings, overprint varnishes and matted, filled or flake-loaded effect grades 25 to 45 s	DIN 4 mm cup, ISO 2431, at 25 C, timed to first break, taken at the same point in the circuit each time	Climbs with water or solvent loss and with matting agent swell over a shift; a matted, filled or haptic coating is run at the top of its window rather than thinned into it, because thinning separates the effect from the vehicle.
Delivered UV dose, peak irradiance and wavelength band	80 to 150 mJ/cm2 for a normal coating; 150 to 250 mJ/cm2 typical for UV metallics; 200 to 400 mJ/cm2 typical for structure coatings, with a penetrating source. Record the peak irradiance figure alongside each dose	Band matched radiometer carried through the press on the substrate at running speed, in the same position each time; record peak irradiance in W/cm2 and total dose in mJ/cm2 for each band together with the press speed	Falls steadily with lamp hours, dirty quartz and a tarnished reflector, well before anything looks different to the eye. Cure at depth is set by irradiance as well as by dose, so the same dose delivered slowly at low irradiance will not drive the same depth of cure.
Gel lamp setting at the structure station	Recorded per job as a dose, a peak irradiance and a press speed, not as a lamp percentage alone	Same band matched radiometer at the gel station, on the substrate, at running speed	Drops with lamp age; crystal size grows or collapses with it, which is why texture wanders while the coating batch is unchanged.
Gloss differential, drip-off	The differential agreed at sampling on the stock concerned, recorded as the matt reading, the gloss reading and the difference. On high gloss coated board this is typically 60 to 80 gloss units at 60 degrees; on lighter coated, uncoated or recycled boards a 30 to 50 unit differential is the realistic ceiling and is agreed with the customer at sampling	ISO 2813, 60 degrees; 85 degrees where the matt is very low	Narrows as primer weight falls or the flood weight rises; also narrows when the coater warms and the applied flood weight moves with it.
Coefficient of friction of the finished surface	Agreed band for the gluer and the packing line, static and kinetic both stated, with the method that set the band stated alongside it	ASTM D1894, coated face against itself and against steel, with the sled load, sled speed and conditioning recorded with every result; conditioned and tested at 23 C and 50 % RH, minimum 4 h, measured 24 h after the run. On folding boxboard state whether the band was set by D1894 or by the inclined plane static method used in carton plants (TAPPI T 815); the two do not give the same figure and a band agreed on one cannot be judged on the other	Moves for one to two days as wax and slip additive migrate to the surface, so a value taken at the delivery is not the value the gluer sees.
Substrate surface energy	38 to 42 mN/m on film; check the actual reel, not the specification sheet	Dyne pens or ISO 8296 test inks, ASTM D2578 where a laboratory figure is needed	Treatment ages down on the reel over weeks, and additives bloom to the surface, so an old reel reads lower than the day it was treated.

Specialty and Effect InksControl variables

Control variables

What to hold, and how to measure it

Variable	Target	How it is measured	How it drifts
Ink and coating temperature at the duct or pan	20 to 25 C	Thermometer or IR probe in the pan and in the duct, not the hall temperature	Rises through the shift from roller and pump friction, and viscosity falls with it. The applied film then moves, in the direction set by the feed system in the film weight row above, without anyone touching a setting.
pH of aqueous metallic and effect inks	The supplier band for the grade, typically 8.5 to 9.0, with an action limit at the top of the band and a stop-and-quarantine limit agreed with the supplier, typically about 0.3 units above it	Calibrated pH meter at 25 C, read before any judgement about viscosity is made	Rises with amine or ammonia additions and falls as ammonia flashes off. Aluminium is amphoteric, so drift in either direction matters: hold the band with the matched additive and never correct body with ammonia.
Entrained air and foam in pumped coatings	No standing foam at the chamber or the pan, and a drawn sample clearing within the time stated for the grade	Visual check at the chamber, the pan and the return line, plus a sample drawn into a measuring cylinder and left to stand; record pump speed and chamber level with it	Rises as the drum empties and the pump starts to draw air, with a worn chamber seal, at high coater speed and on thin low viscosity grades. Micro-foam prints as pinholes and as an uneven feel long before a foam head is visible.
Stack or rewound reel temperature	Below 35 C before the pile is converted	Probe pushed into the pile at mid height, 30 min after the delivery	Heavy effect films carry cure heat into the pile and the centre stays warm for hours, which is where blocking and set-off start.

Specialty and Effect InksControl variables

The mechanism

Why a metallic goes grey

A metallic is a mirror made of flakes lying flat at the top of the film. Anything that stops them leafing, breaks them, leaves the layer discontinuous or fills the space above them turns the mirror into grey pigment. Film weight, shear and the overprint coating decide the effect; pigment strength does not.

Specialty and Effect InksThe mechanism

02 | 20 faults

Faults

Symptom, cause, check, change, confirm. The trap is the move to avoid.

Fault 1 of 20

Silver prints grey, gold prints brown

WHAT YOU SEE

The metallic solid looks like a dull dark grey or a muddy olive rather than a metal, and it looks worse next to the retained sample than it did in the duct. Turning the sheet in the light changes it very little, which is the tell.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Film weight too low for a continuous flake layerA leafing pigment is carried to the air interface by the low surface energy of its stearate coating, and it lies flat because the flake is 10 to 30 micron across while the film is only 1.5 to 2.5 micron deep. Below roughly 1.5 g/m2 there is simply not enough flake laid down to close the surface: the layer is discontinuous, the gaps and the roughness of the stock scatter, and the solid reads grey however well the individual flakes are oriented. That is why raising the film weight works and raising the pigment strength does not.
The ink has been over worked by pumping, stirring or a long roller trainAluminium and brass flakes are thin platelets that bend and fracture under shear, and a broken or curled flake has no flat face to reflect from.
Reduced with a varnish, reducer or thinner that is not matched to the gradeThe leafing agent on the flake surface is a fatty acid layer, and a strong solvent or monomer resolubilises it, after which the flake sinks into the film instead of leafing at the top.
Absorbent, matt or uncoated stockThe vehicle drains into the sheet before the flakes have leafed, and the surface roughness breaks the mirror up even where the flakes did orient.
Over emulsified on an offset unitWater carried into the ink disturbs the flow and the leafing step, and the solid comes off grey and weak.

Specialty and Effect InksSilver prints grey, gold prints brown

Fault 1 of 20 · continued

Silver prints grey, gold prints brown

CHECK, IN THIS ORDER

Weigh the film: cut matched printed and unprinted areas side by side on the same sheet and weigh both on a four place balance, then cross-check against ink consumption per 1 000 sheets divided by the printed area. UF250MT-S30 Silver and UF250MT-G30 Gold need 1.5 to 2.5 g/m2, not the 1.0 to 1.5 g/m2 of a process colour.
Read 60 degree gloss on the metallic solid, ISO 2813; a correctly leafed silver reads high, and a low reading at correct film weight points to orientation and not to weight.
Ask what went into the duct: check whether press varnish, reducing paste or a general purpose thinner was added, and how much.
Look at how the ink is handled: pumps, recirculation, stirrers and the number of rollers it passes through before the plate.
Check the batch number against the batch the retained sample was made from, and on offset check fount conductivity and pH and take an emulsification sample; on flexo check anilox volume against the grade's recommendation.

THEN CHANGE

Raise the film: heavier anilox volume, more ink feed or a double hit on the same unit, and re-weigh to confirm you are in the 1.5 to 2.5 g/m2 band. Raise the delivered dose with it, because more flake screens more of the cure.
Take the metallic off circulation: hand fill the duct or chamber, stir gently by hand, and do not run it through a pump or a fine filter.
Remove unmatched additions; if the ink genuinely needs adjusting, use only the reducer stated for the grade and keep it inside the stated maximum.
Give the metallic its own unit as a solid, and put a matched UniCure coating over it to protect the leaf rather than leaving it bare.
If the stock is uncoated or matt, print a sealer or a white ground first so the flakes have a closed surface to leaf on.

CONFIRM IT IS FIXED

Side by side against the agreed physical sample at the agreed viewing geometry, with the film weight recorded and 60 degree gloss (ISO 2813) back inside the band agreed at sampling. Take the check sheets from mid run at speed, not from the first pull.

THE TRAP

Reaching for more pigment strength, a fuller duct or harder stirring. Flooding the film past the point where flake can orient makes it greyer, not brighter, and adds set-off; harder stirring fractures the very flakes that make the effect.

Specialty and Effect InksSilver prints grey, gold prints brown (continued)

Fault 2 of 20

UV metallic hard on top, soft and poorly anchored underneath

WHAT YOU SEE

The silver or gold feels dry at the delivery and passes a light rub, but a tape check lifts it off the board, a fingernail marks the solid the next day, and an overprint coating applied later lifts or wrinkles it. The heaviest solids fail first while fine detail and the process colours on the same sheet are correct.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

The flake screens the film from the energy that has to cure itAluminium and brass flake reflect and absorb across the UV band, and a correctly leafed layer sits at the top of the film, which is exactly where it screens best. The energy is spent before it reaches the resin under the flake, so a UV metallic screens its own cure in a way no clear coating does and it cures from the top down.
Dose left at the process colour settingA UV metallic needs substantially more delivered energy than a process ink at the same film weight, of the order of 150 to 250 mJ/cm2 against 80 to 150 mJ/cm2 for a process colour on the same press, so a station left at the process figure undercures the metallic while every other unit is right.
Film weight raised to fix the appearance without raising the doseThe remedy for a grey silver is more film, and more film is more flake in the light path, so the cure fault is created by the fix for the appearance fault unless the dose moves with it.
Wrong wavelength for a flake loaded filmThe short wavelengths are attenuated first, so what little energy reaches the base of a metallic is at the long end of the band. A source and a photoinitiator that only work at the short end leave the base uncured however long the lamp runs.
Overprint coating applied over an uncured metallicThe coating cures and shrinks on top of a film that is still mobile underneath, so the whole build lifts at an edge or a crease, and the fault is then read as a coating adhesion failure when it is a metallic cure failure.

Specialty and Effect InksUV metallic hard on top, soft and poorly anchored underneath

Fault 2 of 20 · continued

UV metallic hard on top, soft and poorly anchored underneath

CHECK, IN THIS ORDER

MEK double rubs to ASTM D5402, cotton pad under a 1 kg load, on the uncoated metallic solid 24 h after the run; take the sample to the laboratory rather than the solvent to the delivery where the plant does not permit solvent at the press.
Tape the intact metallic solid and report what comes away; cross-cut to ISO 2409 on the production board where the construction allows a lattice to be cut in the coating.
Band matched radiometer carried through on the substrate at running speed at that station; record peak irradiance in W/cm2 and dose in mJ/cm2 and compare with the figures the job was qualified at.
Weigh the film and establish whether it was raised during the run to correct the appearance.
Check lamp hours, quartz cleanliness and reflector condition at that station before any material is changed.

THEN CHANGE

Raise delivered dose and peak irradiance at the metallic station to the qualified figure for the grade, which is higher than the process colour figure on the same press.
Where dose alone will not reach the base, split the metallic over two units at roughly half the weight each with a cure between, rather than one heavy pass.
Confirm from the grade's data sheet, or with the supplier, that the photoinitiator absorbs at the source's wavelength before any lamp is changed; an LED array in front of a short wavelength initiator makes through cure worse, not better.
Clean quartz and reflector and replace an aged lamp before adjusting settings. Isolate and lock off the unit, let the lamp house cool, wear gloves and eye protection, clean quartz with IPA on a lint-free wipe, keep the ozone extraction running until the unit is cold, and follow the plant's mercury spill procedure if a lamp breaks. Never look at a running lamp or run a unit with a shutter or guard removed.
Do not coat, laminate or convert a metallic that has not met the rub figure; hold the pallet until it has.

CONFIRM IT IS FIXED

MEK double rubs to ASTM D5402, cotton pad at 1 kg, meeting the agreed figure on the uncoated metallic 24 h after the run, conditioned at 23 C and 50 % RH; no metallic removed by a tape check on the production board; and the overprint coating intact over the metallic after creasing on the production construction.

THE TRAP

Judging the cure by touching the surface. A metallic cures from the top down, so the surface is the part that is always hardest, and a thumb on a silver solid says nothing about the resin under the flake that is holding it to the board.

Specialty and Effect InksUV metallic hard on top, soft and poorly anchored underneath (continued)

Fault 3 of 20

Gold darkens in the pile or on the shelf

WHAT YOU SEE

The gold matched the sample on press and has gone dull, brown or slightly green in the pallet, on a stored reel, or on the pack weeks later. It is usually worse at the edges of the pile, in the part of the stack that saw moisture, or under a coated area.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Brass flake is copper and zinc, and it tarnishesGold bronze pigment is a copper zinc alloy, not gold. It oxidises and reacts with sulphur compounds in service, and because the flake is a fraction of a micron thick, a very small amount of surface reaction changes the colour of the whole print.
Moisture in the stock or the storeWater carries the reaction, so damp board, a cold pallet brought into a warm hall, or an unwrapped pallet in a humid store darkens far faster than the same job kept dry.
Aqueous coating outside the metallic's pH bandAqueous overprint varnishes are ammonia or amine stabilised and commonly sit at pH 8 to 9, and brass is attacked outside a narrow band, so the coating meant to protect the gold can be what darkens it.
Sulphur bearing board, adhesive or ink in the constructionSome recycled and virgin boards, and some adhesives, carry sulphur compounds that tarnish copper alloys, which is why the same gold is stable on one board and darkens on another.
Heat and pressure in the pile or the laminatorBoth accelerate the reaction, and pressure holds the flake in contact with whatever is tarnishing it.

Specialty and Effect InksGold darkens in the pile or on the shelf

Fault 3 of 20 · continued

Gold darkens in the pile or on the shelf

CHECK, IN THIS ORDER

Compare the retained press sheet against the pallet and against a sheet kept sealed and dry from the same run, so a change in service is separated from a mismatch at the press.
Measure the pH of the overprint coating against the band stated for the metallic before the two are put in line again.
Record the store: temperature, humidity, whether the pallets were wrapped, and how long they stood.
Run the same gold on an alternative board from a different source under the same conditions, to separate the construction from the ink.
Where a number is wanted, measure the effect print at the agreed geometry and measurement mode on the same areas each time, so the drift is recorded rather than argued.

THEN CHANGE

Specify a stabilised or passivated gold bronze grade for the construction and the shelf life, and state at quotation what the class will and will not do.
Use the matched coating over the gold and check its pH against the metallic's band; an unmatched general purpose aqueous varnish is the common source.
Wrap and store pallets dry, below 30 C, off cold floors, and convert in date order.
Change the board or the adhesive where the trial shows the construction is the source.
Where the shelf life cannot be met by brass, move that area to cold foil or a metallised substrate and price it as such rather than promising it from the ink.

CONFIRM IT IS FIXED

A sample from the run held with the pack for the agreed period at the agreed temperature and humidity shows no visible shift against the retained sample at the agreed geometry, and the coated and uncoated areas of the same sheet have moved together rather than apart.

THE TRAP

Correcting a darkened gold on press by shading it back with yellow or orange. The tarnish carries on after the correction, so the job ends up on the far side of the sample in the other direction and there are now two faults to unpick instead of one.

Specialty and Effect InksGold darkens in the pile or on the shelf (continued)

Fault 4 of 20

Drip-off contrast weak or patchy, craters in the flood

WHAT YOU SEE

The matt areas are not properly matt, or the contrast is there on one side of the sheet and gone on the other. Sometimes the gloss flood also shows small round craters or fisheyes. Often it looked right on the make ready and faded during the run.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Primer film weight has fallenThe de-wetting is driven by the surface tension difference between the primer and the flood, and a thin primer is simply wetted out by the gloss coating instead of repelling it.
Flood coating weight has risenA heavier flood carries enough material to bridge and level over the primer, so the coating closes the matt areas it should have pulled back from.
Coating temperature and viscosity drift in the chamberAs the coater warms the flood thins, cell release improves, the applied weight rises and the surface tension relationship the effect depends on moves with it.
Silicone, spray oil or release agent contaminationA trace of silicone lowers the flood's surface tension so it wets the primer it is supposed to de-wet; the same contamination on the substrate or in the air gives round craters and fisheyes in the flood, because the coating retracts from each low energy spot. It usually arrives from a previous job, from a spray can in the hall, from press lubricant or from a release coated stock.
Coater condition, not the materialsA worn anilox, a blanket with a low patch or unstable chamber pressure lays an uneven flood, and the patchiness then repeats at the coater's circumference.

Specialty and Effect InksDrip-off contrast weak or patchy, craters in the flood

Fault 4 of 20 · continued

Drip-off contrast weak or patchy, craters in the flood

CHECK, IN THIS ORDER

Weigh both films separately on matched areas cut side by side: the primer should sit at 1.5 to 3.0 g/m2 and the flood at 4 to 8 g/m2.
Measure the gloss differential, ISO 2813 at 60 degrees, at five positions across the sheet and record the matt reading, the gloss reading and the spread, not just the best difference.
Measure flood viscosity with a DIN 4 mm cup to ISO 2431 at 25 C and take the coating temperature in the chamber.
Check whether the patchiness or the crater pattern repeats at a fixed distance down the sheet, which points at the anilox, blanket or chamber rather than at either material.
Look for silicone sources before blaming the coating: aerosol sprays in the hall, press lubricants, a release coated stock, and the previous job through that coater; and check the anilox cell volume and condition with a cell volume gauge or a microscope, and the blade pressure.

THEN CHANGE

Restore the primer weight first and re-measure the differential before touching the flood.
Bring the flood back to the lower end of its band rather than the top, and hold the coater temperature at 20 to 25 C.
Wash out and re-fill with clean flood where silicone contamination is suspected, and remove the source from the hall; contamination cannot be corrected by adjusting weights.
Change or reset the anilox, blanket or chamber where the patchiness maps to the coater.
If the design needs more contrast than the materials give on that stock, change the primer grade rather than pushing either weight out of window.

CONFIRM IT IS FIXED

The differential agreed at sampling on that stock, measured to ISO 2813 at 60 degrees at five positions across the sheet with matt, gloss and difference all recorded, the spread inside the agreed tolerance, no craters visible at arm's length, and both film weights logged.

THE TRAP

Adding more gloss flood to chase contrast. A heavier flood floods the matt areas, drops the differential further and raises set-off and blocking risk in the pile at the same time. It is also worth remembering that the achievable differential is set by the stock: on a lighter coated or recycled board the flood itself may only reach 55 to 70 gloss units, so a coated board figure can be arithmetically impossible however well the job runs.

Specialty and Effect InksDrip-off contrast weak or patchy, craters in the flood (continued)

Fault 5 of 20

Structure coating soft under a cured skin

WHAT YOU SEE

The top feels hard and the job looks finished, but a fingernail or a die-cut edge presses into it, and the next day the print shows a mark under the texture. Often the sheet blocks in the pile despite a dry surface.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Delivered dose has fallen without anyone noticingLamp hours, dirty quartz and a dull reflector cut output steadily, and heavy films are the first work to fail when that happens. On a job that cured through last time and does not now, this is the cause until it is ruled out.
Coating applied heavier than the qualified figureCure depth is not linear with thickness, so a coating that was qualified at 40 g/m2 can fail through cure at 60 g/m2 with everything else unchanged.
Gel step took too much of the energyIf the gel lamp is set too high it converts the surface early, and the skin it forms then screens the full cure lamp that follows.
Pigmented or heavily filled grade run at a clear coat dosePigment and filler scatter and absorb at every interface, which shortens the path the energy travels into the film, so the figure that cures a clear does not cure the filled version of it.
Wrong wavelength for the film thicknessAt 30 to 80 g/m2 the top of the coating absorbs the shorter wavelengths and screens the bottom, so the surface cures and the base never receives enough energy. This is the qualification stage fault, and the one to reach for only when the job has never cured through.

Specialty and Effect InksStructure coating soft under a cured skin

Fault 5 of 20 · continued

Structure coating soft under a cured skin

CHECK, IN THIS ORDER

Check lamp hours, quartz cleanliness and reflector condition on that unit first; it is free and it takes two minutes.
Carry a band matched radiometer through on the substrate at running speed and read peak irradiance and dose at the structure station, then compare with the qualified figures. Cure depth is set by irradiance as well as by dose, so a dose alone does not describe the station.
Weigh the film on matched cut areas and compare with the job specification.
Cut a section through the coating with a fresh blade and look at the base under magnification; a soft or cheesy base is visible and a surface rub test will not find it.
MEK double rubs to ASTM D5402, cotton pad at 1 kg, on the surface and on a sheet cut open, taken 24 h after the run. Only the first three checks should happen before any material is changed.

THEN CHANGE

Clean the quartz and reflector and replace the lamp if hours are high, working to the isolation and cool-down rules, before changing dose settings.
Bring the coating weight back to the qualified figure and re-section.
Re-set the gel lamp to the recorded job figure rather than to whatever gives the fastest looking set.
Split a very heavy relief into two lighter passes with a cure between, rather than one pass the lamp cannot reach through.
Only then, match the source and the coating together: move that unit to an iron doped mercury lamp or to a 385 to 405 nm array, and only with a coating whose photoinitiator absorbs at that wavelength, confirmed from the data sheet or with the supplier before any lamp is bought or fitted. Putting an LED array in front of a coating initiated at 250 to 320 nm makes through cure worse, not better. Gallium doping belongs to opaque pigmented films; a heavy clear structure coating is normally an iron doped or long wavelength LED case.

CONFIRM IT IS FIXED

A cut section shows a hard base with no soft layer, MEK double rubs to ASTM D5402 at 1 kg meet the agreed figure 24 h after the run, and cross-cut adhesion to ISO 2409 on the production board, read 24 h after the run at 23 C and 50 % RH, is class 0 or 1.

THE TRAP

Slowing the press and adding dose at the same wavelength. More of an energy the top of the film already absorbs only hardens the skin further, embrittles it and bakes the sheet, while the base stays exactly as soft as it was. The opposite trap is to start by re-equipping the curing station, which is the most expensive remedy in the section and rarely the cause on a job that used to cure.

Specialty and Effect InksStructure coating soft under a cured skin (continued)

Fault 6 of 20

Pearl shows mottle, cloud and streaks

WHAT YOU SEE

The pearl solid looks blotchy, with cloudy patches and fine directional streaks, and the shimmer appears and disappears as the sheet is turned. It usually looks worst in large open areas.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Anilox cell opening or mesh aperture too small for the plateletMica and borosilicate platelets run from about 5 micron on fine satin grades to 200 micron and above on coarse sparkle grades, with effect work commonly at 10 to 60 micron. When the opening is not several times the platelet size the flakes bridge the cells and transfer in clumps.
Film too thin to hold the platelets flatA pearl effect is an orientation effect; if the film is thinner than the flakes need to lie down in, they sit at angles and the surface reads as cloud instead of as lustre.
Uneven ground under a transparent effectPearl pigment is largely transparent, so any variation in the white or the base colour beneath it shows straight through and is read as pearl mottle. Uneven substrate absorbency does the same thing by draining the vehicle unevenly.
Vehicle too thin, so the platelets settle or clusterLow viscosity lets the flakes move and group before the film sets, and the groups print as cloud.
The ink has been filtered or over workedFine filtration removes the larger platelets that produce most of the lustre, and shear breaks the rest, leaving a duller and more uneven effect.

Specialty and Effect InksPearl shows mottle, cloud and streaks

Fault 6 of 20 · continued

Pearl shows mottle, cloud and streaks

CHECK, IN THIS ORDER

Get the actual particle size grade from the data sheet for this job rather than assuming a range, and compare it with the anilox cell opening or the screen mesh aperture; the opening should be several times the largest platelet.
Weigh the film on matched cut areas and compare with the weight the sample was made at.
Print the pearl over a controlled solid white on one half of a test sheet and compare with the pearl direct on stock; if the mottle goes, the ground was the fault.
Measure viscosity with a DIN 4 mm cup, ISO 2431, at 25 C and take the pan temperature.
Check what filters and screens the ink passed through on the way to the press, and check the pigment batch number against the batch the retained sample was made from, since particle size distribution varies between batches and the same press settings then give a different effect.

THEN CHANGE

Change to a coarser, higher volume anilox or a lower mesh count so the platelets transfer whole.
Raise the film weight into the band the effect was sampled at, and re-check the lustre at three viewing angles.
Lay a controlled white or base colour under the pearl and hold that solid steady.
Take the pearl off recirculation and fine filters; stir by hand, gently, and only to redisperse settlement.
Where mottle persists on an absorbent stock, seal the surface first so the vehicle does not drain before the platelets orient.

CONFIRM IT IS FIXED

Viewed against the retained sample at three angles under the agreed light, the solid is even with no visible cloud at arm's length, film weight and pigment batch are logged, and the same result repeats on sheets taken at the start, middle and end of the run.

THE TRAP

Running the ink through a fine filter or a mill to cure the mottle. That removes or fractures exactly the platelets that create the effect, and the ink comes back clean, even and dead.

Specialty and Effect InksPearl shows mottle, cloud and streaks (continued)

Fault 7 of 20

Metallic dulls after the overprint varnish

WHAT YOU SEE

The metallic looked correct as it came off the printing unit and greyed once the coating went on, or greyed a day later. The uncoated edges of the sheet still look bright, which makes the cause obvious once you look for it.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

The coating wets the leafed flake layerThe mirror is produced at an interface between metal and air, and a varnish that penetrates into the leaf layer replaces that air, so the specular reflection is lost.
The metallic was not fully cured or dry before it was coatedA soft ink film lets the coating mix into the top of it, dragging the flakes out of alignment.
Coating weight too highMore varnish means more penetration into the leaf layer before it sets, and a thick film also levels over the flake structure.
Chemically aggressive coating or adhesiveAluminium and brass flake are attacked by water at pH outside a narrow band, and in practice the risk is an over-alkaline aqueous coating, since aqueous overprint varnishes are ammonia stabilised and commonly sit at pH 8 to 9. Strong solvents and acid catalysed systems attack the flake and the leafing layer directly, and brass darkens most readily of all.
Heat from lamination or a dryer after coatingHeat softens the ink film and lets the coating move further into it, so a job that looked right off the press greys in the laminator.

Specialty and Effect InksMetallic dulls after the overprint varnish

Fault 7 of 20 · continued

Metallic dulls after the overprint varnish

CHECK, IN THIS ORDER

Run a control: coat half the sheet and leave half bare, then compare 60 degree gloss (ISO 2813) and appearance side by side.
Confirm the metallic was fully cured before the coating station, with MEK double rubs to ASTM D5402 at 1 kg on an uncoated sample.
Weigh the coating film on matched cut areas.
Check the coating's pH against the metallic's own band before the two are put in line, and whether the varnish is the matched UniCure grade or a general purpose one.
Log any heat the printed sheet or web saw after coating, with a data logger or thermal strip.

THEN CHANGE

Use the matched coating specified with the metallic rather than the house general purpose varnish.
Cure or dry the metallic fully before it reaches the coating station.
Drop the coating weight to the lower end of its band; protect the leaf rather than bury it.
Where a heavy or aggressive coating is unavoidable, change to a non-leafing metallic, which gives a coarser reflection but holds its appearance under a coating.
Reduce post-coating heat, or move the effect to a position in the construction where it does not see it. Where a scan area falls on or beside a metallic or foiled ground, check the scan grade on the production pack before the run; a metallic background is a contrast problem for the scanner, it is made worse by a coating change, and it cannot be corrected once the job is printed.

CONFIRM IT IS FIXED

The coated area matches the retained coated sample, not the bare print, at the agreed geometry, and the gloss difference between coated and uncoated areas is inside the band agreed at sampling. Re-check 24 h later, since some dulling develops overnight.

THE TRAP

Adding more varnish to bring the shine back. The extra film sinks further into the leaf layer and greys it more, and the job then also blocks in the pile.

Specialty and Effect InksMetallic dulls after the overprint varnish (continued)

Fault 8 of 20

Cold foil lifts at the edges or pinholes

WHAT YOU SEE

The foil looks complete on the press but the edges of fine detail lift when the sheet is handled, or the solid shows small unfoiled specks. Often it appears after die-cutting or after the overprint coating goes on.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Adhesive and foil release layer are mismatchedThe foil has to release from its carrier more readily than it lets go of the adhesive, and if that balance is wrong the foil breaks at the image edge; this is a system mismatch, not an adhesive fault.
The adhesive is not wet and at the intended tack at the nip, or the cure after the nip is wrongIn cold foil the UV adhesive is printed wet and the foil is nipped into it uncured; the curing lamp comes after the nip, curing the adhesive through the transparent carrier on narrow web systems that strip after cure, or after the carrier has been stripped on sheet-fed units. Too little post-nip dose leaves a soft bond, so the foil releases with the carrier or lifts later. Energy reaching the adhesive before the nip, from a stray lamp, an interdeck source or a reflection, skins it so it will not take the foil at all. There is no pre-nip cure lamp to set.
Adhesive film weight outside the windowBelow the window the adhesive cannot key the foil at fine edges; above it, the adhesive squeezes past the image and takes foil where it is not wanted, which then breaks away.
Rough or absorbent substrateThe foil is a thin continuous layer that cannot bridge surface pits, and each pit becomes a pinhole.
Overprint coating attacking the foiled edgeA coating applied over foil can creep under a weakly bonded edge and lift it, so a fault created at the nip shows up two stations later.

Specialty and Effect InksCold foil lifts at the edges or pinholes

Fault 8 of 20 · continued

Cold foil lifts at the edges or pinholes

CHECK, IN THIS ORDER

Weigh the adhesive film on matched cut areas; 1.5 to 3.0 g/m2 is typical for cold foil.
Radiometer at the post-nip curing station on the substrate at running speed, peak irradiance and dose, against the qualified figure; and check that no lamp, interdeck source or reflection is reaching the adhesive before the nip.
Tape adhesion on the foiled area 24 h after the run at 23 C and 50 % RH: apply a defined tape to the intact foil, not to a cut lattice, remove it at a consistent angle and speed, and report what came away, which is no foil removal, partial foil removal, or board fibre tear. A fibre tear result means the board surface failed first and the foil bond was not measured.
Run a short test with an alternative foil at the same adhesive settings; if the lift goes, the fault is the pairing.
Look at the substrate surface under magnification for pits and fibre, and try the same settings on a smoother stock.

THEN CHANGE

Set the post-nip dose to the qualified figure and screen off any stray energy reaching the adhesive before the nip, before adjusting weight or nip pressure.
Bring the adhesive weight back into the window from whichever side it has drifted.
Change the foil to one qualified with this adhesive, and treat adhesive, foil and any overprint coating as one set that is re-qualified whenever any of the three changes.
Prime or seal a rough stock, or move to a smoother grade, where pinholes are the complaint.
Keep foil out of creases and glue laps at artwork stage rather than trying to hold it there on press.

CONFIRM IT IS FIXED

Tape adhesion on the intact foil 24 h after the run at 23 C and 50 % RH with no foil removal and the failure mode recorded, and the foiled detail intact after die-cutting and creasing on the production board. Reserve the ISO 2409 cross-cut for the overprint coating on the board, where it belongs; cutting a lattice through foil creates the very edges the test then measures.

THE TRAP

Raising the nip pressure or the adhesive weight to force the foil down, or hunting for a lamp before the nip to raise. Extra adhesive squeezes out past the image, picks foil up where it is not wanted and contaminates the next station; part-curing the adhesive before the nip guarantees the non-transfer and edge break you are trying to cure.

Specialty and Effect InksCold foil lifts at the edges or pinholes (continued)

Fault 9 of 20

Soft touch marks and scuffs in transit

WHAT YOU SEE

Fingerprints, gloss marks and scuff lines show on the matt velvet surface, usually on the corners and the panel faces after packing, and sometimes straight off the delivery.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Surface undercure, particularly on LEDThe surface cures last under an LED array and is the layer oxygen inhibits, so a soft touch coating can be hard underneath and tacky on top, where every mark is made.
The grade is at the soft end of the rangeHand feel and scuff resistance pull in opposite directions; past a certain softness, marking is inherent to the surface and no press setting removes it.
Film weight above the windowA heavier soft touch film is softer to the finger and easier to mark, and it holds cure heat into the pile as well.
Stack pressure and heat in the pileWarm heavy films under their own pile weight deform at contact points, and those points show as gloss marks.
Handling and transitBare hands leave oil on a matt surface and it shows against the low gloss; loose packing lets panels rub against each other in the carton.

Specialty and Effect InksSoft touch marks and scuffs in transit

Fault 9 of 20 · continued

Soft touch marks and scuffs in transit

CHECK, IN THIS ORDER

MEK double rubs to ASTM D5402, cotton pad at 1 kg, at the delivery and again 24 h later, to separate undercure from inherent softness; handle the solvent to the rules in the methods section.
Radiometer check on the substrate at the curing station at running speed, peak irradiance and dose. Where the press has nitrogen inerting, read the inerting level from the press instrumentation and the oxygen alarm, not by approaching the station; never defeat an interlock, and treat the area around an inerted station as an oxygen depletion risk.
Weigh the film on matched cut areas; 3 to 5 g/m2 for aqueous soft touch and 6 to 10 g/m2 for UV soft touch and haptic are the usual windows, and the window belongs to the grade, not to the class.
Scuff test on the production board with a Sutherland type rub tester, 1.8 kg block, 100 cycles against unprinted stock, conditioned and tested at 23 C and 50 % RH, against a retained sample.
Probe the pile temperature 30 min after the delivery and record the pile height.

THEN CHANGE

Fix the surface cure first: raise peak irradiance and dose at the final station, clean the quartz, or use inerting where it is fitted and proved.
Move to a grade balanced for scuff rather than for maximum hand feel, and re-sample the feel with the customer.
Bring the film weight to the lower end of the grade's window and re-check the feel against the sample.
Cut the pile height, cool the pile and leave the job 24 h before converting.
Do not hand handle or convert sheets whose cure has not been confirmed; quarantine them until the rub figure is met. Where the surface is fully cured and gloves are wanted only to keep finger oils off a matt film, clean cotton or nylon inspection gloves are appropriate. Where cure is in doubt, use disposable nitrile gloves, never cotton, and change them rather than re-use them, because cotton absorbs uncured acrylate and holds it against the skin for the length of a shift.

CONFIRM IT IS FIXED

MEK double rubs to ASTM D5402 at 1 kg meeting the agreed figure 24 h after the run, Sutherland rub at 1.8 kg for 100 cycles with no visible gloss change, both conditioned at 23 C and 50 % RH, and a packed transit trial on the actual carton and pack pattern.

THE TRAP

Laying more soft touch coating on to cure the marking, or slowing the press to dry it harder. A heavier film marks more easily, and slowing the press adds heat to the sheet without addressing the oxygen inhibited surface layer that is causing it.

Specialty and Effect InksSoft touch marks and scuffs in transit (continued)

Fault 10 of 20

Effect film blocks in the stack or reel

WHAT YOU SEE

Sheets stick together in the pile, or the rewound reel picks and tears when it is unwound. The surface felt dry at the delivery, which is why the pile was built to normal height.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Cure at depth incomplete on a heavy filmAn uncured base stays mobile and continues to give up material at the interface under pile pressure, even under a hard skin.
Heat retained in the pileHeavy effect films carry cure heat into the stack, the centre stays warm for hours and every coating is softer warm than cold.
Surface undercure from oxygen inhibitionThe last few micron at the surface cure slowest, especially under LED, and a tacky surface under load bonds to the sheet above.
Residual solvent or water in a solvent or aqueous effect inkSolvent left in a heavy film plasticises it, and the film blocks at temperatures it would otherwise survive. The same retained solvent is what produces an odour complaint from the filled pack weeks later.
Pile height and pressure set for plain printThe pressure at the bottom of a full pallet is the load that decides blocking, and effect work needs a lower pile than plain work.

Specialty and Effect InksEffect film blocks in the stack or reel

Fault 10 of 20 · continued

Effect film blocks in the stack or reel

CHECK, IN THIS ORDER

MEK double rubs to ASTM D5402 at 1 kg at the delivery and again after 24 h, and a cut section through a heavy film.
Pile temperature with a probe at mid height, 30 min and 2 h after the delivery.
Radiometer reading on the substrate at running speed on the heaviest solid, peak irradiance and dose.
Smell a sample taken from the middle of a cooled pile, and where the pack carries a sensitive product arrange a residual solvent or sensory test by the laboratory method agreed for the grade; a 30 to 80 g/m2 structure coating or a heavy solvent metallic holds solvent and cure by-products, and the complaint usually arrives from the filled pack rather than from the press.
A weighted block test on a stack of sample sheets held overnight at the plant temperature, before the whole job is piled.

THEN CHANGE

Correct cure at depth and at the surface before touching anything else, with a penetrating wavelength matched to the grade's photoinitiator for depth, and irradiance, dose or proved inerting for the surface.
Halve the pile height and let the delivery cool; fan or interleave where the job allows.
Add drying or slow the web where residual solvent is the finding, and increase air volume rather than temperature alone.
Delay converting by 24 h and store the pallets below 35 C.
Where the surface is inherently soft, specify a scuff resistant overcoat or a slip additive within the agreed COF band.

CONFIRM IT IS FIXED

An overnight weighted block test at plant temperature, on the production stock, separates without picking or gloss marking; the pile temperature is below 35 C before the job is converted; and where odour was the complaint, the agreed sensory or residual solvent result on the filled pack.

THE TRAP

Reaching for more anti set-off spray powder on a soft touch or haptic surface. The powder embeds in the soft film, shows as grit and destroys the hand feel the customer bought, while the real cause, the warm undercured film, is untouched.

Specialty and Effect InksEffect film blocks in the stack or reel (continued)

Fault 11 of 20

Flake ink piles on anilox, plate or blanket

WHAT YOU SEE

Density falls away over a few hundred metres or a few hundred sheets, the anilox looks dull and packed, and flake builds at the edges of solids on the plate or blanket.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Anilox cell opening too small for the flakeThe cells act as a filter, holding flakes back while the vehicle transfers, and once a cell is packed it never releases a full volume again.
Drying in on the anilox or the plateSolvent or water flashing at the roll leaves a flake rich residue that sets in the cells, and the effect is fastest on open areas and on stopped presses.
Viscosity has been dropped to clear the pilingThinning lets the vehicle run away from the flake, so the solids pack harder and the piling accelerates.
Doctor blade pressure or angle wrongA blade that rides on a cushion of ink leaves a flake rich film on the land, which builds up and transfers as streaks.
Short or over pigmented inkA short ink does not flow back after splitting, so flake accumulates where the film is thinnest and the shear is highest.

Specialty and Effect InksFlake ink piles on anilox, plate or blanket

Fault 11 of 20 · continued

Flake ink piles on anilox, plate or blanket

CHECK, IN THIS ORDER

Inspect the anilox under a microscope for packed cells and measure cell volume with a cell volume gauge.
Viscosity with a DIN 4 mm cup, ISO 2431, at 25 C, taken at the same point in the circuit each time; flexo press grades sit at 16 to 22 s and flake loaded effect grades at 25 to 45 s, so check which window the grade belongs in before deciding it is thick.
Check blade pressure, angle and wear, and the chamber seal condition.
Take pan and hall temperature, and note the air movement over the open ink.
Track the fall in density against running metres or sheets to separate a piling fault from a supply fault. Where the system is solvent based, also confirm that drums and the press are bonded and earthed before decanting; flake inks and heavy solvent films build static that pulls dust into the solid, disturbs transfer, and is an ignition risk in a solvent area.

THEN CHANGE

Change to a coarser, higher volume anilox chosen for the flake size rather than for the colour.
Set a clean down interval for the anilox with a proper deep clean rather than a wipe, and clean at every stop.
Correct the blade before changing the ink, and re-seal the chamber if it is drawing air.
Add the matched retarder for solvent grades rather than plain thinner, to stop drying in at the roll.
Restore viscosity to the stated band and re-test; if the piling clears, the thinning was the cause.

CONFIRM IT IS FIXED

Solid density and film weight hold inside the agreed band over 2 000 sheets or 1 000 m at production speed, with the anilox clean at the end of that run.

THE TRAP

Thinning with solvent or water the moment piling appears. It looks better for ten minutes, then the vehicle drains away from the flake, the cells pack harder and the run is lost along with the anilox.

Specialty and Effect InksFlake ink piles on anilox, plate or blanket (continued)

Fault 12 of 20

Heavy effect film cracks on the crease or the cut edge

WHAT YOU SEE

A white or broken line along the crease of a structure coating, a raised crystal, a heavy glitter or a cold foil; foil breaking along the fold; or fine crazing at the die-cut edge. It shows on the folded carton and not on the flat sheet, which is why it is found at the gluer or at the customer.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

The film is harder and less extensible than the board it sits onA heavily crosslinked UV film has little elongation, and a crease puts the outer surface into tension over a small radius, so the film fails before the board does.
Overcured, not undercuredEnergy past the point of full cure keeps raising crosslink density and keeps lowering elongation, so the usual remedy for a soft film is the cause of a cracked one.
Film weight above the qualified figureThe strain at the outer surface of a crease rises with the thickness of the layer being bent, so a heavier effect film cracks at a crease a thinner one survives.
Creasing rule, matrix and grain directionA narrow rule, a tight matrix channel or a crease across the grain forces a small radius and the effect film takes the whole of that strain; the same job creases cleanly with rule and channel set for the coated caliper.
Cold, dry stockBoard and film are both less able to take the strain when they are cold and dry, so a job that folded in summer cracks in a January conversion.

Specialty and Effect InksHeavy effect film cracks on the crease or the cut edge

Fault 12 of 20 · continued

Heavy effect film cracks on the crease or the cut edge

CHECK, IN THIS ORDER

Fold samples from the run in both grain directions on the production board, not on a trial stock, and look at the crease under magnification.
Weigh the film on the panel and over the crease area and compare with the qualified figure.
Radiometer on the substrate at running speed at that station, peak irradiance and dose, compared with the qualified figures; an overcured film is as likely here as an undercured one.
Check creasing rule height and width, and matrix channel width and depth, against the coated caliper, and check the grain direction of the blank.
Record the temperature and humidity of the stock at the gluer, and compare against a sample conditioned at 23 C and 50 % RH.

THEN CHANGE

Bring the delivered dose back to the qualified figure rather than to the highest the press will give.
Bring the film weight back into the window, and keep the heavy effect off the crease at artwork stage where the design allows.
Reset the rule and matrix for the coated caliper, and lay the blank so the crease runs with the grain where the layout allows.
Move to a grade formulated for folding where the design puts a heavy effect across a crease; flexibility and scuff resistance are traded against each other and that choice belongs to the customer, made at sampling.
Condition the stock before conversion and do not fold cold pallets straight from a winter store.

CONFIRM IT IS FIXED

Blanks from the start, middle and end of the run, folded on the production board conditioned at 23 C and 50 % RH, show no crack visible at arm's length on any crease, and a folded and glued carton from the same run survives the agreed transit or drop trial.

THE TRAP

Adding dose to make a cracked film tougher. Past full cure the extra energy only raises crosslink density, which lowers elongation further, so the film cracks more readily than before and the board underneath is baked at the same time.

Specialty and Effect InksHeavy effect film cracks on the crease or the cut edge (continued)

Fault 13 of 20

Cartons jam or glue laps pop open

WHAT YOU SEE

Blanks slip or grab in the folder-gluer hopper and feed section after an effect coating, or the glue lap opens later even though the gluer ran. The plain version of the same carton runs without complaint.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

The coefficient of friction has changedSoft touch, haptic and matt surfaces are either far grippier or far more slippery than plain board, and the gluer is set for plain board.
Effect coating in the glue lapAdhesive has to key into the board fibre, and a coating in the lap gives it a low energy, closed surface to bond to instead.
Slip additive or wax migrating to the surfaceAdditives continue moving to the surface for a day or two after the run, so the COF at the gluer is not the COF measured at the delivery.
Texture on a structured or sand surfaceA raised texture reduces the real contact area for both feeding and gluing, so the same nip and the same glue bead do less work.
Glue chemistry not matched to the coated surfaceA water based PVA needs an absorbent surface to set against, and a sealed effect surface stops it losing water where it has to.

Specialty and Effect InksCartons jam or glue laps pop open

Fault 13 of 20 · continued

Cartons jam or glue laps pop open

CHECK, IN THIS ORDER

Measure COF to ASTM D1894, static and kinetic, coated face against itself and against steel, with sled load, sled speed and conditioning recorded, at 23 C and 50 % RH, 24 h after the run and not at the delivery. On folding boxboard, record whether the agreed band was set by D1894 or by the inclined plane static method used in carton plants (TAPPI T 815), because the two do not give the same figure.
Inspect blanks for coating in the glue lap and compare against the artwork keep-out.
Do a fibre tear test on glued laps after 24 h; the requirement is board fibre tearing, not a measured load.
Check the coating film weight on the panel faces.
Run a small trial through the gluer at production speed before committing the pallet.

THEN CHANGE

Restore the glue lap keep-out at artwork stage, and correct it on the plate or screen, not at the gluer.
Adjust the slip additive within the agreed COF band and re-qualify the band with the gluer operator, using the same method that set it.
Change the adhesive to one suited to the coated surface, hot melt where a water based adhesive cannot set.
Let the pallets stand 24 h so the surface stabilises before gluing, and store below 35 C.
Re-set the gluer feed and nip for the measured COF rather than for the standard board setting.

CONFIRM IT IS FIXED

Fibre tear on five laps taken from the run 24 h after gluing, and a full pallet through the gluer at production speed with no feed stoppages, with the measured COF and the method that produced it recorded against the agreed band.

THE TRAP

Raising the glue temperature or the glue quantity to force a bond over a coated lap. It will hold in the plant while it is warm and open on the shelf, and the fault is then found by the customer rather than by you.

Specialty and Effect InksCartons jam or glue laps pop open (continued)

Fault 14 of 20

Crystal texture varies across the sheet

WHAT YOU SEE

The raised crystal is fine at one end of the sheet and coarse at the other, or the texture changes between the first and last pallet of the same job with the same batch of coating.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Gel lamp output has driftedThe texture scale is set by how far the surface is taken at the gel step, so a lamp losing output produces a different crystal from the same coating.
Press speed changedDose is energy per unit area at the running speed, so a speed change is a dose change at both the gel and the full cure station.
Stock or coating temperature variesA warmer film flows differently in the seconds between gel and cure, and the texture that sets is a flow result.
Dwell between gel and full cure changedThe texture develops in that interval, so a different unit spacing, a different lamp in service or a different speed changes the crystal even at identical doses.
Film weight variation across the sheetRelief scale follows film thickness, so an uneven screen or coater lays a thicker film on one side and a coarser crystal with it.

Specialty and Effect InksCrystal texture varies across the sheet

Fault 14 of 20 · continued

Crystal texture varies across the sheet

CHECK, IN THIS ORDER

Radiometer reading at the gel station and at the full cure station, on the substrate at running speed, peak irradiance and dose, compared with the job record.
Film weight from matched cut areas at both sides and the centre of the sheet.
Surface temperature of the stock entering the coater with an IR thermometer.
Lamp hours and quartz condition at the gel station.
Confirm the actual dwell: which lamps are in service, at what spacing, and at what speed.

THEN CHANGE

Re-set the gel dose to the recorded figure for the job, and log it with the speed and the irradiance.
Hold one press speed for the run; treat a speed change as a re-make ready on structure work.
Clean the quartz and replace an aged gel lamp, to the isolation and cool-down rules, before adjusting the coating.
Level the film across the sheet by correcting the screen or coater rather than by raising the overall weight.
Condition the stock so it enters at a stable temperature, and note the hall temperature on the job record.

CONFIRM IT IS FIXED

Crystal compared against the retained sample at three positions across the sheet and at the start, middle and end of the run, with gel dose and irradiance, full dose, speed and film weight recorded on the job sheet.

THE TRAP

Chasing the texture with coating weight while the gel lamp is left wherever it happens to be. Weight and gel dose both move the crystal, so changing one to compensate for the other leaves a job that cannot be repeated next time.

Specialty and Effect InksCrystal texture varies across the sheet (continued)

Fault 15 of 20

Fluorescent looks dull and fades on shelf

WHAT YOU SEE

The fluorescent solid lacks the glow the sample had, looks dirty rather than bright, and after a few weeks in a lit store it has visibly dropped.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Judged under a light with no UV componentThe glow comes from short wavelength energy being absorbed and re-emitted in the visible, so a viewing booth lamp without a UV component under-reports a fluorescent and the print is condemned for a fault that exists only in the light it was viewed under. This is the first thing to rule out because it is free and it takes ten seconds.
A UV absorbing varnish, laminate or film over the effectAnything that blocks the incoming short wavelength energy blocks the emission, so the effect is lost under a coating that looks perfectly clear.
Printed over an uncontrolled or absorbing groundFluorescents are semi-transparent and any ground that absorbs light kills the emission, which is why they are laid over a solid white.
Film weight too lowFluorescent pigments are resin particles with low tinctorial strength, so they need a heavier film than a process colour to build enough material to fluoresce.
Light fastness of the classDaylight fluorescent pigments are low in light fastness by nature, typically blue wool 1 to 3 with the pink, magenta and orange shades at the bottom of that range, so fading over weeks is a property of the class rather than a fault.

Specialty and Effect InksFluorescent looks dull and fades on shelf

Fault 15 of 20 · continued

Fluorescent looks dull and fades on shelf

CHECK, IN THIS ORDER

View under a light source with a UV component as well as under D65, and record which was used and what each showed.
Compare a coated and an uncoated area of the same sheet, and check the overprint varnish or laminate for UV absorber.
Print a test with and without a solid white ground and compare side by side.
Weigh the film on matched cut areas and compare with the film the sample was made at.
Where shelf life is in question, expose against ISO 105-B02 blue wool references and state the rating achieved on the actual shade, at full tone and at a stated tint.

THEN CHANGE

Fix the viewing condition and agree it in writing with the customer before the job is judged.
Remove the UV absorbing coating from over the fluorescent, or move the effect above it in the construction.
Lay a solid opaque white under the fluorescent and hold that white steady across the run.
Raise the film weight or run a double hit on the same unit.
Where the fluorescent will not survive the intended shelf life, say so in advance and offer a higher fastness shade at lower brightness so the customer chooses knowingly.

CONFIRM IT IS FIXED

Matched against the retained sample under the agreed light source including its UV component, with the film weight and the white ground recorded, and the blue wool rating for the actual shade, at full tone and at a stated tint, stated to the customer in writing before the job ships.

THE TRAP

Adding a UV absorbing overprint to protect the fluorescent from fading. It does slow the fade, and it kills the glow immediately, so the customer sees the loss of the effect long before they would have seen the fade.

Specialty and Effect InksFluorescent looks dull and fades on shelf (continued)

Fault 16 of 20

Glitter drops out, streaks or blocks the mesh

WHAT YOU SEE

The glitter solid has bare patches and comet tails, the screen blinds part way through a run, and the coverage is heavy at the start of the stroke and thin at the end.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Mesh aperture too small for the flakeGlitter flakes are commonly 50 to 400 micron. The aperture must be at least twice, and preferably three times, the largest flake, and the coarsest practical graphic mesh, about 10 to 20 threads per cm, opens to roughly 700 to 900 micron. That caps screen printing at roughly 200 to 250 micron flake; above that size no screen will pass it and a mesh below the rule sieves the flake out and blinds.
Flake has settled in the pot or on the screenGlitter is much denser and larger than the pigment it sits with, so it settles quickly and the ink in use becomes progressively depleted.
Stencil too thin for the flakeThe stencil has to carry a deposit deeper than the flake, or the flakes are crushed and sheared at the stencil edge instead of passing through and being anchored.
Squeegee pressure too high or durometer too hardExcess pressure crushes the flake against the mesh, drives ink under the stencil edge and blinds the open area rather than clearing it.
The ink has been filtered or pumpedAny filter fine enough to be useful removes the glitter, and a pump breaks the flake, so the effect leaves with the housekeeping.

Specialty and Effect InksGlitter drops out, streaks or blocks the mesh

Fault 16 of 20 · continued

Glitter drops out, streaks or blocks the mesh

CHECK, IN THIS ORDER

Get the flake size from the data sheet and calculate the mesh aperture from mesh count and thread diameter; compare against the two to three times rule and against the 200 to 250 micron practical ceiling.
Measure the stencil thickness and compare with the flake size.
Check squeegee durometer, typically 65 to 75 Shore A for this work, and the set pressure and angle.
Stir the pot and reprint; if the coverage returns, settlement is the finding.
Look at the mesh under magnification for flakes bridging the openings rather than for dried ink.

THEN CHANGE

Open the mesh: a much lower thread count chosen against the flake size, within what the aperture rule allows.
Build the stencil thicker so it can carry a deposit deeper than the flake.
Reduce squeegee pressure, and use the softest blade that still clears the mesh.
Stir the ink gently and regularly during the run; never filter it and never run it through a pump.
Where mesh and flake cannot be reconciled, the flake is above the printable ceiling and the answer is a decision, not a press setting: a finer glitter grade, or a different application method such as adhesive and scatter, agreed with the customer before the job is booked. Confirm at the same time what the glitter is made from, since synthetic polymer glitter is restricted in some markets under microplastics legislation; state the formulation position only and leave conformity of the finished pack to be assessed on the pack.

CONFIRM IT IS FIXED

Full coverage with no comets or bare patches on the solid, held for 500 impressions at running speed, and compared against the retained sample at the same viewing distance the pack will be seen at.

THE TRAP

Increasing squeegee pressure to push ink through a blinding mesh. It crushes the flake, floods under the stencil edge and turns an intermittent coverage problem into a ruined stencil and a lost screen.

Specialty and Effect InksGlitter drops out, streaks or blocks the mesh (continued)

Fault 17 of 20

Thermochromic already triggered on the reel

WHAT YOU SEE

The colour change has happened before the pack is filled, or the ink comes back to colour but weaker each time, and some areas never recover their full shade.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Heat somewhere in convertingThe system changes at its stated activation point and does not know whether the heat came from a dryer, a lamination nip or a hot store.
Activation point too close to the process temperatureA grade specified for the pack in use is often specified without the drying and lamination temperatures being checked against it.
Capsules broken by shearThe colour change chemistry lives inside microcapsules, and stirring hard, milling or pumping ruptures them, which loses the change permanently rather than temporarily.
Solvent or monomer attacking the capsule wallAn unmatched reducer or a strong monomer swells the wall and lets the contents leach, so the effect weakens over hours or days.
Light exposureLeuco dye systems are very low in light fastness by nature, typically blue wool 1 to 2, and direct sunlight degrades them in hours rather than weeks, so a reel left in daylight loses strength before it is converted.

Specialty and Effect InksThermochromic already triggered on the reel

Fault 17 of 20 · continued

Thermochromic already triggered on the reel

CHECK, IN THIS ORDER

Map the temperature the reel or sheet actually sees, with a data logger or thermal indicator strips, through every station and store, against the stated activation point.
Test a retained sample of the unprinted ink: if it changes correctly, the fault was on press, not in the ink.
Look at the printed film under magnification for ruptured capsules.
Check what was added on press and whether it was the reducer stated for the grade.
Check the storage of the reel: light, temperature and how long it stood.

THEN CHANGE

Take the heat out of the process, starting with the dryer that carries the highest temperature, and re-map.
Where converting genuinely cannot stay below the activation point, specify a grade with a higher activation point rather than manage it by procedure.
Hand stir gently, never mill or pump, and keep the ink off recirculation.
Use only the matched reducer, within the stated maximum.
Store and transport the reels dark and below the agreed temperature, and print the job close to the converting date.

CONFIRM IT IS FIXED

On a controlled hot plate or water bath with a calibrated probe: full colour when cold, colour cleanly lost within plus or minus 2 C of the stated activation temperature on heating, and full depth returned on cooling at the stated reversion temperature, which sits several degrees below the activation point. Record both figures, since the hysteresis gap, typically 3 to 10 C depending on the grade, is a property of the grade and a tester who expects the colour to return at the activation point will record a pass as a fail. Repeat through three heat and cool cycles with no loss of depth against the retained sample.

THE TRAP

Turning the dryer down across the whole job to protect the effect. The solvent then stays in the film, attacks the capsule walls and causes odour and blocking, so the job is lost to a second fault created by the fix for the first.

Specialty and Effect InksThermochromic already triggered on the reel (continued)

Fault 18 of 20

Haptic sand feels smooth in patches

WHAT YOU SEE

The sand texture is right in the centre of the sheet and smooth at one edge, or right at the start of the run and flat by the end. The coating looks identical in the drum.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Filler has settled in the drum or the panMicrospheres and matting fillers are lighter or heavier than the vehicle and separate on standing, so the coating in use is not the coating that was qualified.
Anilox or screen screening out the beadsIf the cell opening or mesh aperture is not comfortably larger than the bead, the beads are held back and only the vehicle transfers, giving a smooth film.
Film weight outside the window for the gradeThe texture depends on the beads standing proud of the dry film while still being anchored in it. Too thin and there is not enough coating to carry or hold them; too heavy and the film levels over the beads and buries the texture. The window is narrow and it belongs to the grade and its bead size.
Circulation stopped, or the wrong pump on the circuitA static pan lets the filler separate within minutes, and the effect drifts through the run while every setting stays where it was. A gear or centrifugal pump does the opposite damage: it grinds the beads and crushes expanded microspheres, which gives the same smooth patches from the other direction.
Coating has been filteredA filter fine enough to catch dirt is fine enough to catch the beads, and the filter is where the effect went.

Specialty and Effect InksHaptic sand feels smooth in patches

Fault 18 of 20 · continued

Haptic sand feels smooth in patches

CHECK, IN THIS ORDER

Stir the drum thoroughly and reprint; if the texture returns, settlement is confirmed.
Weigh the film at both sides and the centre of the sheet and compare against the grade's stated window and the weight the sample was made at.
Compare bead size from the data sheet with the anilox cell opening or mesh aperture.
Measure COF to ASTM D1894 at three positions across the sheet, with load, speed and conditioning recorded, as an objective reading of the texture.
Check whether the coating passed through any filter or fine screen on the way to the press, and identify the pump type on the circuit.

THEN CHANGE

Stir before the run and keep the material moving, but with low shear circulation only: a diaphragm or peristaltic pump, or pan agitation, never a gear or centrifugal pump. This is the opposite of the rule for flake effects, which come off circulation entirely. Beads settle and need movement; flakes shear and need stillness, so decide which family the material belongs to before you touch the circuit.
Move to a coarser anilox or a lower mesh count chosen for the bead size.
Bring the film weight back into the grade's window and re-check the feel against the sample.
Remove fine filters from the circuit; strain only through a mesh coarser than the beads if dirt is a real risk.
Do not thin the coating to clear a transfer problem; thinning speeds settlement and makes the drift worse. Where the smooth areas map to the stock rather than to the machine, seal the surface first, since uneven absorbency drains the vehicle unevenly and reads as flat patches and orange peel.

CONFIRM IT IS FIXED

Coefficient of friction to ASTM D1894 inside the agreed band at three positions across the sheet, with load, speed and conditioning recorded, feel matched against the retained sample by the customer's own inspector, and the same result on sheets from the start, middle and end of the run.

THE TRAP

Filtering the coating to get rid of what looks like grit in the pan. The grit is the effect, the filter takes it out, and the coating then runs beautifully and does nothing.

Specialty and Effect InksHaptic sand feels smooth in patches (continued)

Fault 19 of 20

Aqueous metallic gasses, drums swell

WHAT YOU SEE

A drum or container bulges, the lid is tight or hisses when it is loosened, and the ink foams and thickens on press. Sometimes it is noticed first as an unexplained viscosity rise overnight.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Aluminium reacting with waterAluminium is amphoteric: it is attacked by water both above roughly pH 9 and below roughly pH 4, and the reaction releases hydrogen, which is what raises the pressure in the container. Aqueous grades rely on a passivated or encapsulated flake and on the pH being held inside the supplier band, so drift in either direction matters.
pH moved by additions on pressAmmonia or amine added to correct viscosity raises pH, and above the supplier band it accelerates the reaction that generates the gas; an acidic additive or contamination attacks the flake from the other side.
Untreated or unstabilised aluminium pigment in an aqueous systemAqueous grades use passivated or encapsulated flake for exactly this reason, and a solvent grade pigment used in water has no such protection.
Storage above the stated temperatureThe reaction rate rises with temperature, so a drum in a hot store gasses far faster than the same drum in the ink room.
Mixed with an amine containing varnish or extenderBlending an alkaline auxiliary into the metallic raises the pH of the mixture regardless of where the metallic started.

Specialty and Effect InksAqueous metallic gasses, drums swell

Fault 19 of 20 · continued

Aqueous metallic gasses, drums swell

CHECK, IN THIS ORDER

Treat a swollen container as pressurised: do not open it at the press. Move it to a ventilated area, keep ignition sources away, and have it vented slowly and deliberately by trained staff to the plant's procedure.
Measure pH with a calibrated meter at 25 C before any judgement about viscosity is made.
Check what has been added since the container was opened, and in what quantity.
Check the store temperature and how long the stock has been held.
Confirm from the data sheet that the pigment grade is intended for aqueous systems.

THEN CHANGE

Stop using the affected container for production and quarantine it.
Work only with a pigment grade stabilised for aqueous use.
Hold pH inside the supplier band and correct body with the matched additive rather than with ammonia.
Store below 30 C, keep containers out of the sun and off the press deck, and use stock in date order.
Do not decant metallic back into a part used drum; keep a dedicated container and a short open life.

CONFIRM IT IS FIXED

pH stable within about 0.2 units over a working shift, no container distortion, and a gassing test on a retained sample held seven days at 40 C in a vented or pressure relief gassing bottle, in a ventilated oven away from ignition sources, by the supplier laboratory or by trained staff to the plant's own procedure, showing no measurable gas evolution and no viscosity rise outside the stated band. Never seal a suspect metallic in an ordinary container and warm it.

THE TRAP

Adding ammonia to bring the viscosity back. It raises the pH, feeds the reaction that is causing the gassing, and turns a materials handling problem into a pressurised container.

Specialty and Effect InksAqueous metallic gasses, drums swell (continued)

Fault 20 of 20

Photochromic is slow or barely visible

WHAT YOU SEE

The print hardly changes outdoors, or it takes far longer to develop than the sample did, and indoors under shop lighting nothing happens at all. Sometimes the opposite: it comes off the press fully darkened and will not clear.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

A UV absorbing varnish, laminate or film over the effectPhotochromic dyes are switched by energy at roughly 300 to 380 nm, so a coating or a film that absorbs in that band starves the effect of its trigger.
Judged under light with no UV content, or straight off the pressShop and office lighting contains very little of the band the dye responds to, so the effect is condemned in a condition it was never intended to work in. The reverse happens at the delivery: the curing lamps emit exactly the band that switches the dye, so a fresh print can come off fully darkened, or apparently dead from saturation, and recover after a period in the dark. Judging it at the delivery reports a fault that is not there.
Film weight too lowThe depth of colour developed depends on how much dye is in the light path, so a thin film gives a weak change even in full sun.
Ambient temperatureThe reversion back to clear is temperature dependent, so on a hot day the effect looks weaker because it is fading almost as fast as it develops.
Fatigue after repeated cycling or sustained exposurePhotochromic dyes have a finite cycle life and low light fastness, typically blue wool 1 to 2, so they lose response gradually. This is a property of the class and not a manufacturing fault.

Specialty and Effect InksPhotochromic is slow or barely visible

Fault 20 of 20 · continued

Photochromic is slow or barely visible

CHECK, IN THIS ORDER

Check every layer above the effect for UV absorber, and compare a coated and an uncoated area of the same sheet outdoors.
Put a sample in the dark at room temperature for a few hours and re-test before condemning it, so the curing lamps are ruled out as the reason it looks dead or stuck dark.
Weigh the film on matched cut areas against the film weight the sample was made at.
Test under a controlled UV-A source and record the development time, rather than relying on whatever light is to hand, and record the ambient temperature alongside the result.
Test a retained unprinted sample of the ink; if it performs, the loss happened in the construction or on press.

THEN CHANGE

Remove the UV absorbing layer from over the effect, or place the photochromic on the outermost surface.
Raise the film weight into the sampled band, or run a double hit.
Agree the test condition, the rest period after curing, and the expected development and reversion times with the customer in writing before the job runs.
State the cycle life and the expected service life honestly at quotation, so the effect is specified for the right application.
Keep the printed stock dark and cool before despatch to avoid using up cycle life in the warehouse.

CONFIRM IT IS FIXED

After a rest in the dark, under the agreed UV-A source at the agreed distance, the print develops to the sample depth within the stated time and reverts in shade within the stated time, with film weight and ambient temperature recorded on the test.

THE TRAP

Assuming the ink is dead and laying on more of it. Photochromic systems saturate, so beyond the sampled film weight the extra ink adds cost and no visible change, while the varnish blocking the UV stays exactly where it is.

Specialty and Effect InksPhotochromic is slow or barely visible (continued)

At the press

One page to work from, and the methods behind every number.

Quick reference

One page at the press

Symptom	Check this first	Change this first
Silver grey, gold brown	Film weight on matched areas cut side by side on one sheet	Raise to 1.5 to 2.5 g/m2 and raise the dose with it; take the ink off pumps
UV metallic soft under the flake	MEK rubs at 1 kg on the uncoated metallic at 24 h, plus a tape check	Raise dose and irradiance at that station to the metallic figure, not the process figure
Gold darkened in the pile or on the shelf	Coating pH against the metallic's band, and the store humidity	Matched coating inside the band; wrap and store dry below 30 C
Drip-off contrast weak, patchy or cratered	Primer weight, then 60 degree gloss on both areas at five positions	Restore primer to 1.5 to 3.0 g/m2 before touching the flood; find the silicone source
Structure coating soft underneath	Lamp hours, quartz and reflector, then radiometer at running speed	Clean and relamp, then coat weight back to the qualified figure
Pearl mottle and cloud	Anilox cell opening against the actual platelet size from the data sheet	Coarser anilox or lower mesh; stop filtering the ink
Metallic dulls under the varnish	Coat half the sheet, leave half bare, compare	Matched coating at lower weight, inside the pH band, over a fully cured ink
Cold foil lifting at edges	Adhesive weight, and radiometer at the post-nip cure station	Set post-nip dose to the qualified figure and screen off stray pre-nip energy

Specialty and Effect InksQuick reference

Quick reference

One page at the press

Symptom	Check this first	Change this first
Soft touch marking and scuffing	MEK rubs at 1 kg at delivery and again at 24 h	Fix surface cure first; then cut the pile height
Sheets blocking in the pile	Pile temperature at mid height after 30 min	Halve the pile, cool it, hold the job 24 h
Flake ink piling, density falling	Anilox cells under a microscope	Coarser anilox and a proper clean down; do not thin
Effect film cracking on the crease	Fold the production board both grain ways and look under magnification	Dose back to the qualified figure, not higher; reset rule and matrix for the coated caliper
Cartons jam or laps pop	COF at 24 h with load, speed and conditioning recorded, not at delivery	Clear the glue lap keep-out; reset the gluer to the measured COF
Crystal texture wandering	Radiometer at the gel station at running speed	Reset gel dose to the job record and hold one speed
Fluorescent dull or fading	View it under a light with a UV component before anything else	Fix the viewing condition; then remove the UV absorbing varnish
Glitter dropping out or blinding	Mesh aperture against the largest flake, and against the 200 to 250 micron ceiling	Open the mesh, thicken the stencil, drop squeegee pressure

Specialty and Effect InksQuick reference

Quick reference

One page at the press

Symptom	Check this first	Change this first
Thermochromic triggered early	Data logger through every dryer, nip and store	Take out the hottest step or move to a higher activation grade
Haptic sand smooth in patches	Stir the drum and reprint; identify the pump type on the circuit	Coarser anilox or mesh for the bead size, low shear circulation only, never filter
Aqueous metallic gassing, drum swollen	Treat as pressurised, do not open it at the press	Quarantine the container, have it vented by trained staff, then measure pH
Photochromic slow or weak	Anything UV absorbing above it, and was it judged in daylight or UV-A rather than at the delivery	Rest it in the dark, then remove the UV absorbing layer or move the effect to the outer surface

Specialty and Effect InksQuick reference

Test methods

The measurements this guide relies on

Measurement	Method	What it tells you, and the usual acceptance
Film weight by gravimetry	No standard number; described method	Cut matched printed and unprinted areas from the same sheet, side by side and as close together as the design allows, and weigh both on a four place balance. Know the limit before quoting a number from it: a 2 g/m2 film on 300 g/m2 board is under 1 % of the weight on the balance, while the board's own basis weight varies by 1 to 2 % within a pallet, so a pair taken from different sheets returns mostly board variation. Cutting a bigger area does not fix it, because it scales the ink and the board variation together, and replicates only reduce the scatter by the square root of the number of pairs. What works is pairs cut adjacent on one sheet where the basis weight is correlated; a piece weighed before and after it is printed, which removes the substrate entirely and is the laboratory and drawdown method; and consumption per 1 000 sheets or per 1 000 m divided by the printed area as a cross-check. Straight printed against unprinted gravimetry is reliable where the film is a large fraction of the substrate weight, which means screen structure coatings at 30 to 80 g/m2, and work on film rather than board. Record which method produced the figure. Typical windows: metallics 1.5 to 2.5 g/m2, aqueous soft touch 3 to 5 g/m2, UV soft touch and haptic 6 to 10 g/m2, gloss flood 4 to 8 g/m2, screen structure coatings 30 to 80 g/m2.
Gloss	ISO 2813	60 degrees on the printed and coated surface, 85 degrees where the matt is too low for 60 degrees to resolve. Drip-off is specified as the differential agreed at sampling on the stock concerned, recorded as the matt reading, the gloss reading and the difference, because substrate absorbency moves the reading more than coating chemistry does: typically 60 to 80 gloss units on high gloss coated board, and 30 to 50 units as the realistic ceiling on lighter coated, uncoated or recycled boards.
Cross-cut adhesion	ISO 2409	Taken 24 h after the run on the production substrate, conditioned at 23 C and 50 % RH, since heavy effect films shrink as they cure and the interface settles overnight. Class 0 to 1, meaning flaking of not more than 5 % of the lattice area, is the usual acceptance; it is a property of the ink, the substrate and the construction together. It is a test for a coating on a substrate: do not use it on a cold foil area, where cutting the lattice creates the edges it then measures and the tape lifts board fibre before it lifts foil.
Solvent rub	ASTM D5402	MEK double rubs with a cotton pad under a 1 kg load, run on the surface and, for heavy films, on a cut open section. It separates a surface cure problem from a through cure problem, and it is the routine check that a heavy effect film or a UV metallic is safe to convert. Handle MEK as a highly flammable solvent and an eye and respiratory irritant: nitrile gloves, eye protection, local extraction or a well ventilated area away from lamps, dryers and any ignition source, a closed dispensing bottle, no more solvent at the press than the test needs, and used pads to a lidded solvent waste bin. Where the plant does not permit solvent at the delivery, take the sample to the laboratory rather than doing the test at the press.
Scuff	No standard number cited; Sutherland type rub tester, house method	Sutherland type rub tester, 1.8 kg block, 100 cycles against unprinted stock, conditioned and tested at 23 C and 50 % RH, judged against a retained sample for gloss change and colour transfer. Where a job carries its own agreed load and cycle count, record it on the job sheet alongside this default.
Coefficient of friction	ASTM D1894, with TAPPI T 815 as the carton plant alternative	Static and kinetic, coated face against itself and against steel, measured 24 h after the run because slip additive keeps migrating to the surface. Record the sled load, the sled speed and the conditioning, minimum 4 h at 23 C and 50 % RH, with every result; without them two plants produce two different numbers and both call it D1894. D1894 is written for plastic film and sheeting, so on folding boxboard state whether the agreed band was set by D1894 or by the inclined plane static method used in carton plants (TAPPI T 815), because the two do not give the same figure and a band agreed on one cannot be judged on the other. It is the number that predicts folder-gluer, cartoner and packing line behaviour on soft touch, haptic and matt surfaces.
Flow cup	ISO 2431, DIN 4 mm	Supply and press viscosity at 25 C, timed to first break, taken at the same point in the circuit each time. Flexo press grades run at 16 to 22 s; coatings, overprint varnishes and matted, filled or flake loaded effect grades at 25 to 45 s. Matted, haptic and flake loaded grades are run at the top of their stated window rather than thinned into it, because thinning separates the effect from the vehicle.

Specialty and Effect InksTest methods

Test methods

The measurements this guide relies on

Measurement	Method	What it tells you, and the usual acceptance
Light fastness	ISO 105-B02 blue wool references	Reported as a blue wool rating on the full tone unvarnished film and on a stated tint, because tints and reduced shades lose one to two steps against the full tone and that is where the fade is seen first. Where the job carries a coating or laminate, state whether the rating was measured varnished or unvarnished, since that changes the result. Effect systems are rated on the actual shade supplied, not on a class figure: daylight fluorescents are typically blue wool 1 to 3 with the pink, magenta and orange shades at the bottom, and thermochromic and photochromic leuco dye systems typically blue wool 1 to 2, with direct sunlight degrading them in hours rather than weeks. The rating is stated to the customer in writing before the job runs rather than defended afterwards.
Peel and foil adhesion	ASTM F904 for flexible laminates; described tape method for cold foil	For laminated effect constructions where a load figure is meaningful, T-peel on a strip of stated width at the rate given in the method, at 23 C and 50 % RH, reported with its failure mode and confirmed on the customer's own structure. On paper based structures the result is reported as fibre tear rather than as a load. For cold foil, apply a defined tape to the intact foil, not to a cut lattice, remove it at a consistent angle and speed 24 h after the run, and report no foil removal, partial foil removal or board fibre tear; a fibre tear result means the board surface failed first and the foil bond was not measured. ASTM D3330 is the peel method for pressure-sensitive tape and applies only where a tape is itself the test medium, not to a laminate or a foiled board.
Wetting tension	ASTM D2578, or ISO 8296 test inks on the shop floor	Checked on the reel or pallet about to be run, not on the specification sheet, because treatment ages down over weeks. 38 to 42 mN/m is the usual working figure on film before an effect ink or a cold foil adhesive is applied.
Colour measurement of effect prints	No single standard number; state geometry and measurement mode with every figure	A metallic or a pearl cannot be described by a single 45/0 or d/8 reading, because the whole point of the effect is that the colour changes with the angle; where a number is required, use a multi-angle instrument and report the same aspecular angles every time, and treat the retained physical sample as the arbiter. For fluorescents and optically brightened substrates, record the measurement mode, since UV-included and UV-cut conditions give two different answers on the same print and a specification that does not state the mode cannot be judged. Fix geometry, mode, backing, aperture and the number of readings at sampling and keep them for the life of the job.

Specialty and Effect InksTest methods

When the press-floor fixes have not worked

What to send us

The retained physical master sample and a printed sample from the run showing the fault, both unvarnished and varnished where the job carries a coating, with the viewing geometry, the light source and the measurement mode you judged them under.
Printed and unprinted stock from the same reel or pallet, with the substrate supplier, grade and reel or batch number, so the surface can be measured rather than assumed.
The ink and coating batch numbers from the labels, the date the containers were opened, and a list of everything added on press with the quantity and the maximum stated for the grade. Effect batches vary in particle size distribution, so match the batch to the batch the sample was made from before the press is blamed.
The press record for the job: press and unit, anilox volume or mesh and stencil, screen or plate, speed, film weights as weighed and by which method, and the delivered dose and peak irradiance at each station with the radiometer type and band.
For cure faults, a cut section sample and the MEK double rub results at 1 kg at the delivery and at 24 h; for cure at depth, the lamp type, lamp hours, and whether the source is doped mercury or an LED array and at what wavelength, together with the grade's photoinitiator absorption from the data sheet.
For downstream faults, the measured coefficient of friction with the method, load, speed and conditioning that produced it, the glue and gluer settings, a glued, creased and die-cut sample, and the temperature and time history the stock saw between the press and the failure.
For colour change systems, the temperature map from a data logger or indicator strips through every dryer, nip and store, against the stated activation point, plus a sample of the unprinted ink from the same batch and a sample rested in the dark after curing.
For scan and pack level rejects, the actual pack or blank that failed, the scan grade report, and the position of the code against the effect, since a metallic, pearl or foiled ground is a contrast problem for the scanner and not a density problem.
For any food, pharmaceutical or toy contact question, the full pack construction, the filling, the intended contact and the shelf life, so a migration position can be assessed on the finished pack; formulation statements about the ink alone do not answer it, and some effects are not available on that pack at all.

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Specialty and Effect InksTechnical service