Troubleshooting guide

Solvent Based Gravure Inks

Press-floor fault finding for PU lamination and surface print gravure: solvent balance, residual solvent, register, bond after ageing, retort and hot fill.

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.

Fix the solvent balance before you touch the viscosity. Almost every gravure fault that looks like transfer, colour or drying is a blend that has gone fast or alcohol rich in an open pan, and a correction made with a single solvent makes it worse.
Measure the ink where it prints. Viscosity at the pan on a DIN 4 mm cup, DIN 53211 geometry, at 25 C; ink temperature with a probe standing in the pan; treatment with dyne inks on the reel at the unwind. A figure taken at the mixer or read off a film certificate is not the figure the cylinder is seeing.
Treat residual solvent as the first suspect for anything that appears after the job leaves the press: odour, taint, blocking, soft print, bond falling on ageing, tunnelling after retort. Cut and seal a sample early and run headspace GC rather than judging by nose, but do not stand still waiting for the result; the free checks run while the sample is at the lab.
Never quote a peel load without its failure mode, its strip width and its crosshead speed, and never quote it before the adhesive has cured. A lower load ending in film stretch is a better pack than a higher one that splits the ink film, and a load taken at one width cannot be converted to another.
Bond, seal, retort survival, hot fill survival and migration belong to the finished structure, not to the ink. Establish the unprinted bond of the customer's own laminate first; it is the ceiling for anything printed on it.
On a two-component retort job, remember the clock: for 430RT with UniGrav-439HD at the specified dose, pot life is typically 6 to 8 h at 30 C and full crosslink typically 5 to 7 days at 25 C. Confirm both against the current technical data sheet and the batch in use, because both shorten with temperature and with hardener level. Either way, a retort test run on day one is testing an unfinished film.
Two things on this press are safety items and are never traded against quality: the LEL in the drying tunnel, and the handling of the polyisocyanate hardener. A damper closed to save heat and a hardener decanted in the open hall are not shortcuts, they are faults to be reported as faults.

Solvent Based Gravure 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

Solvent Based Gravure InksThe process

Control variables

What to hold, and how to measure it

Variable	Target	How it is measured	How it drifts
Print viscosity at the pan	15 to 18 s on 70 to 110 l/cm tone work; 18 to 22 s on 50 to 70 l/cm solids and lamination white; 16 to 20 s surface-print line work	DIN 4 mm cup, DIN 53211 geometry, sample and cup at 25 +/- 1 C, drawn from the pan and not from the mixer. If an ISO flow cup No. 4 to ISO 2431 is used instead, the seconds are not interchangeable with DIN 4 seconds and the targets above must be re-established on that cup at that cup's own test temperature. State the cup and the temperature with every reading.	Climbs through the run as the fast ester leaves an open pan. Shows first as full, heavy tone and highlights screening out after a stop, before the cup ever reads high.
Solvent blend composition	410PU and 415PW: ethyl acetate 55 to 65 %, n-propyl acetate 15 to 25 %, ethanol 15 to 25 % w/w. 430RT: ester only, ethyl acetate 75 to 85 %, n-propyl acetate 15 to 25 % w/w	Matched reducer by label, UniGrav-495RD or the ester-only version for 430RT; gas chromatography on a pan sample where the balance is in real doubt. Recovered or reclaimed solvent is not a matched reducer: it can carry water, acid and an unknown slow fraction, and it must never go into a hardened 430RT job at all.	Alcohol and the slow fraction enrich as the ester goes off first. Release from the cell worsens, strength falls and the shade drifts grey while the cup still reads on target.
Ink temperature in the pan	As close to 25 C as the hall allows; treat 30 C as a ceiling and act at 28 C. On hardened 430RT keep the pan and the circulation below 28 C	Probe thermometer standing in the pan through the run, logged hourly, not an infrared read on the drum	Climbs with pump work, tunnel air leaking back onto the deck and hall temperature through the afternoon. Every rise speeds evaporation and shortens pot life; pot life falls from 6 to 8 h at 30 C to 4 to 5 h at 35 C and a circulating system runs hotter than the hall.
Dryer profile, extraction and LEL	40 to 50 C at entry rising to 60 to 80 C at exit, with solvent vapour in the dryer below 25 % LEL, or up to 50 % LEL only where a listed continuous LEL monitor with interlocks and alarm is fitted and proved	Deck thermocouples cross-checked with a handheld probe at entry and exit; damper position and LEL reading logged at the start of every shift and after every speed or coverage change	Flattens and goes hot as filters load, as dampers are closed to save heat, and as someone raises the set point to chase a soft print. Closing the exhaust damper to save heat, or bypassing the LEL interlock, moves the tunnel towards a flammable atmosphere; it is a safety fault and is reported as one, not traded against drying.
Web speed against tunnel dwell	The speed at which the running job still measures not more than 5 mg/m2 total retained solvent	Line speed from the press against measured tunnel length, verified by static headspace GC-FID on a sample cut from the running reel	Creeps up once the job settles and the operator is comfortable. Retention rises silently; nothing on the press shows it.
Corona treatment on the reel being run	BOPP and PE: not below 38 mN/m, 40 to 42 preferred. PET: not below 42 mN/m, 44 to 48 preferred for reverse-print lamination. BOPA nylon: not below 44 mN/m. On polyolefins do not exceed about 48 to 50 mN/m	Dyne test inks applied on the reel at the unwind, at three points across the web including both edges, and both on the outer wraps and after 20 to 30 wraps in. Use formamide-free test inks or pens where available and cross-check them once against the classical scale, because the two sets do not always read the same number	Decays week by week in store and slip additive blooms to the surface. The reading varies through the reel in both directions depending on how it was wound, wrapped and stored, so test the outside and 20 to 30 wraps in rather than assuming which part is worse. Over-treatment drifts the other way: above about 48 to 50 mN/m on a polyolefin a weak oxidised boundary layer builds that reads high on a dyne test and peels low in the laminate. The film certificate is older than any reading you take.
Ink film weight and engraving	1.2 to 2.5 g/m2 dry for process colours, higher for solid white; white held on 50 to 70 l/cm at 35 to 45 micron cell depth	Engraving record and cell depth from the cylinder maker, deposit checked by weighing a measured printed area against the same area of unprinted film	Rises whenever highlight loss or mottle is fought with impression, deeper cells or a second hit of white, which moves bond and retention in the wrong direction.

Solvent Based Gravure InksControl variables

Control variables

What to hold, and how to measure it

Variable	Target	How it is measured	How it drifts
Hardener addition and handling on 430RT	UniGrav-439HD at 3 to 5 % w/w on weighed ink, pot life 6 to 8 h at 30 C and 4 to 5 h at 35 C	Weighed against the weighed ink in the pot, never poured by eye; pot life tracked as a 5 s rise on the DIN 4 cup. UniGrav-439HD is a polyisocyanate and a respiratory sensitiser: once an operator is sensitised they react to trace exposures for life. Weigh and add it with nitrile gloves, eye protection and local exhaust at the mixing point; never spray, mist or warm it, and never decant it in the open hall. Keep packs closed and dry, because water in an isocyanate pack generates CO2 and can pressurise and burst a resealed container, so a suspect pack is vented in a ventilated area and not returned to store. Follow the SDS; where EU rules apply, the REACH diisocyanate training requirement applies to everyone who handles it. Rags wetted with hardened ink go to the closed solvent-waste bin, not the floor.	Dose creeps up when someone wants faster development, and pot life collapses. Alcohol contamination works the other way and is silent: it caps the isocyanate without thickening the pot, so no cup reading reveals it.
Winding tension and reel temperature	Tapered tension to the core; reel below 35 C before it is wound hard or stacked	Press tension profile from the panel, reel face and core temperature with an infrared thermometer at the rewind	Raised to cure telescoping, which is exactly the pressure that turns a print that is not yet empty into a blocked reel.
Register tolerance and tension zones	Colour to colour register inside the job's own tolerance, typically 0.1 to 0.2 mm on flexible packaging work; a tension profile set for the film and the gauge and held through the reel rather than trimmed by hand	The press register system reading, cross-checked independently on the reel with a loupe and graticule at three positions across the web, with the tension for every zone read from the panel at the diameter where the job actually runs and not at the start of the reel	Moves whenever something else is cured with tension or with heat: tension raised at the rewind to stop telescoping, a dryer turned up to chase a soft print, one deck running hotter than the rest. The web is stretched either way, so the error follows the reel diameter and comes back after every hand correction.
Doctor blade angle and pressure	Typically 55 to 65 degrees to the tangent, at the lowest pressure that wipes cleanly	The deck's own angle scale and pressure readout, with the blade edge inspected under a loupe at every change and the seat wiped clean. Blades are handled only with the press stopped, the drive isolated and the blade retracted or removed, wearing cut-resistant gloves; used blades go in the blade box, not the general bin	Pressure gets wound on through the shift to chase a line, which drives the trapped particle harder into the chrome and turns a blade change into a re-chrome. It also drifts the other way at speed: as speed and viscosity rise the drag film under the blade thickens and the non-image area starts to haze.

Solvent Based Gravure InksControl variables

The mechanism

Where the solvent actually goes, and when it comes back

The drying tunnel is the only place in a gravure lamination job where residual solvent can be controlled, and the only place where the wrong instinct, more heat, makes it worse. This is the mechanism behind five of the faults in this guide: odour, blocking, bond falling after ageing, tunnelling after retort and failure after a hot fill. Solvent only ever leaves through the film surface, so animate it as arrows leaving through the surface in panels one and two. In panel three animate what is left diffusing through the thickness of the ink layer into the adhesive and sealant plies over days.

Solvent Based Gravure InksThe mechanism

02 | 20 faults

Faults

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

Fault 1 of 20

Drying-in on the cylinder, highlights screen out

WHAT YOU SEE

Highlight dots and vignette tails fade or vanish within minutes of a stop, and come back only partly after the blade has cut a few metres. The cylinder surface feels dry to a gloved finger just before the blade.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Solvent blend too fast for the hallThe ester fraction flashes off the cell wall between the pan and the nip, so the ink films inside the cell before it can transfer.
Viscosity too high for the engravingA thick ink will not release from a shallow 70 to 110 l/cm cell, sits in it for another revolution and sets.
Hot air from the tunnel leaking back onto the deckIt lifts the ink temperature in the pan and on the cylinder face, which accelerates evaporation everywhere at once.
Ink starved or the pan level lowLess of each revolution is submerged, so the cell spends longer in open air before it reaches the nip.
Press stopped with the cylinder out of the inkA static film sets in the cells and the blade cannot clear a dried deposit.

Solvent Based Gravure InksDrying-in on the cylinder, highlights screen out

Fault 1 of 20 · continued

Drying-in on the cylinder, highlights screen out

CHECK, IN THIS ORDER

Read print viscosity in the pan with a DIN 4 mm cup, DIN 53211 geometry, at 25 C, drawn at the pan rather than at the mixer
Take the ink temperature in the pan with a probe thermometer; treat 30 C as the ceiling, and above 28 C the blend is already being pushed faster than it was designed for
Check the tunnel-to-deck seal for hot air blowing back onto the cylinder, with a smoke source or the back of a hand at the entry seal
Check the engraving record for line count and cell depth against the job, and check the blade-to-nip distance
Look at the cylinder face under the blade with the press jogging, for a dulled or filmed area rather than wet ink

THEN CHANGE

Add UniGrav-496SL slow blend in 5 % steps on ink volume, then re-read viscosity
Bring viscosity down 1 to 2 s DIN 4 with the matched reducer UniGrav-495RD, never with a single solvent from the gantry
Seal the air leak from the tunnel, cover the pan and recirculate so the ink is not evaporating in an open tray
Raise the pan level and keep the cylinder in the ink at every stop, jogging rather than standing
Fit or restore the cell-flush or blade shower where the deck has one

CONFIRM IT IS FIXED

2000 m at production speed with no dot loss on the 5 to 10 % tone patches under a loupe, viscosity holding within 1 s DIN 4 on the automatic unit, and a two-minute stop followed by full highlight recovery inside 5 m of restart.

THE TRAP

Reaching for the thinner tin. Straight ethyl acetate drops the cup reading and makes the blend faster still, so the highlights screen out harder ten minutes later. Slow the blend first, then set the viscosity.

Solvent Based Gravure InksDrying-in on the cylinder, highlights screen out (continued)

Fault 2 of 20

Colour drifts from reel to reel through the run

WHAT YOU SEE

The shade at the start and the shade at 3000 m do not match, usually weaker and greyer rather than stronger, and the operator has been toning by eye to hold it.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Solvent balance drifting in an open panThe fast ester leaves first, the alcohol fraction enriches, resin solvency falls and the pigment part-flocculates, so strength drops while the cup can still read on target.
Viscosity corrected by hand at long intervalsBetween corrections the ink is running at a different film weight and a different transfer, so every reel sits somewhere else on the curve.
Ink temperature rising through the shiftWarm ink evaporates faster in the pan and transfers differently, so the drift accelerates in the afternoon.
Press-side toning with pigment while the blend is movingA shade corrected against a solvency fault is wrong the moment the blend is put right, and the correction is permanent.
Contaminated ink, returned stock, settled drum or a mixed reducerAn unmatched or reclaimed solvent, or a drum that has stood for months with the pigment settling hard, changes both the release curve and the dispersion.

Solvent Based Gravure InksColour drifts from reel to reel through the run

Fault 2 of 20 · continued

Colour drifts from reel to reel through the run

CHECK, IN THIS ORDER

Pull the pan viscosity log and look for the shape of the correction pattern, not just the last reading
Take ink temperature in the pan with a probe and compare it to the start of the shift
Draw a sample from the pan, letdown to standard viscosity and lay a drawdown against the approved standard on the same substrate
Confirm the automatic viscosity unit is dosing UniGrav-495RD and not whatever drum is nearest, and that no reclaimed solvent has been drawn on
Check the age of the drum and how it was stirred; run a fineness of grind gauge on a settled or returned drum before it goes back on the job

THEN CHANGE

Cover the pans, recirculate, and set the automatic unit to read every 30 to 60 s
Dose only with the matched reducer for that series; the ester-only version where 430RT is running
Cool the ink circulation and stop hot tunnel air reaching the deck
Stop hand toning and re-standardise the ink from the drum once the blend is stable
Stir a stored drum to the bottom before it is drawn on, and where the ink has been toned repeatedly take it out of circulation rather than carrying it to the next job

CONFIRM IT IS FIXED

deltaE00 not more than 1.5 to ISO 13655, M1, D50, 2 degrees, between the OK pull and every hourly pull, measured on the same backing, over a full reel change.

THE TRAP

Adding toner or a strong base to lift a shade that has gone weak. The strength loss is solvency, not pigment, so the shade goes dirty and unbalanced the moment the blend is corrected, and the ink is then fit for nothing.

Solvent Based Gravure InksColour drifts from reel to reel through the run (continued)

Fault 3 of 20

Fine streaks and lines down the web

WHAT YOU SEE

Hairline lines in solids and heavy tone, running in the web direction, usually in one colour only. Some wander across the web, some sit in one place all run.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

A hard particle trapped under the bladeDried ink skin, a pigment agglomerate or chrome debris holds the blade off the cylinder and scores a channel that keeps refilling.
Blade pressure too high or the edge unevenly honedAn over-pressed blade digs rather than rides, and a nicked edge leaves a permanent line at the same lateral position.
Ink too viscous or too coldRelease from the cell is poor and the drag film at the blade is thicker, so the wipe is uneven and dried skin and agglomerates build at the edge and score. The opposite fault, a thin or starved ink with a low pan level, leaves too little film for the blade to ride on and lets it chatter and cut dry. Correct viscosity and ink temperature to the pan targets before changing any blade setting.
Chrome worn, pitted or scoredBroken cell walls carry ink past the blade in a continuous track that no blade setting will wipe.
Blade oscillation not workingWithout lateral movement any particle stays in one track and cuts a groove into both blade and chrome.

Solvent Based Gravure InksFine streaks and lines down the web

Fault 3 of 20 · continued

Fine streaks and lines down the web

CHECK, IN THIS ORDER

With the press stopped, the drive isolated and the blade retracted or removed, and wearing cut-resistant gloves, draw a folded cloth lightly along the edge so that a nick or burr snags it, then inspect the edge under a loupe. Never run a bare finger along a blade and never do this on a jogging press; used blades go in the blade box
Inspect the circulation filter bag, typically 100 to 150 micron, for holes or for a bag that was never fitted
Read pan viscosity on a DIN 4 mm cup at 25 C and take the ink temperature
Examine the chrome with a magnifier and a low-angle light for score lines; measure the defect repeat against the cylinder circumference
Confirm blade oscillation is running and at its set stroke

THEN CHANGE

Index or change the blade and wipe the blade seat and back-up blade clean before refitting
Fit or replace circulation filtration and strain the ink in the drum
Ease blade pressure back to the lowest that wipes clean, and re-check the angle at 55 to 65 degrees
Correct viscosity and ink temperature to the pan targets
Where the chrome is scored, take the cylinder out of the job; it will not print out. If the score is confined to the chrome, de-chrome, polish and re-chrome. If it has reached the copper or broken cell walls, the cylinder must be de-chromed, the copper stripped or repaired, re-engraved and re-chromed, then re-proofed before it goes back on a job, because re-chroming over damaged copper plates the damage and reproduces the line

CONFIRM IT IS FIXED

500 m clean at running speed, a blade edge with no nicks under a loupe at the end of the run, and no defect repeating at the cylinder circumference.

THE TRAP

Winding blade pressure on to wipe the line away. It presses the trapped particle harder into the chrome, converts a blade line into a permanent score, and turns a two-minute blade change into a re-chrome and a lost cylinder.

Solvent Based Gravure InksFine streaks and lines down the web (continued)

Fault 4 of 20

Speckle and skipped dots in mid tone

WHAT YOU SEE

Tone areas print as a broken, sandy pattern with dots missing at random. It is worse at speed, worse on thicker or colder film, and it looks like a coverage problem rather than a transfer problem.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Electrostatic assist off, wrongly set or defeated by dry airWithout the assist field the ink is not pulled out of the cell across the small gap, so the ink stays in the cell on the harder film.
Impression pressure too low or the roller hard or wornThe film is not pressed into intimate contact with the cell mouth, so the meniscus never breaks.
Viscosity too high for the cell depthA viscous ink cannot leave a deep cell in the contact time available at speed.
Film cold, stiff or poorly wettingA reel brought straight from a cold store does not conform to the cylinder, and low surface energy stops the ink spreading at the point of transfer.
Hall humidity too lowA dry hall lets the web charge and undermines the assist, so the effect appears seasonally in winter.

Solvent Based Gravure InksSpeckle and skipped dots in mid tone

Fault 4 of 20 · continued

Speckle and skipped dots in mid tone

CHECK, IN THIS ORDER

Read the electrostatic assist current and voltage at the panel and confirm polarity against the press maker's setting
Check impression roller hardness with a Shore A gauge against its record, and take a nip footprint across the web
Read pan viscosity on a DIN 4 mm cup at 25 C
Test surface energy with dyne inks on the reel at the unwind against the figure for that film
Check the reel core temperature with an infrared thermometer against hall temperature, rather than trusting how long it has been in the hall

THEN CHANGE

Restore the electrostatic assist and set it to the press maker's figure for the film
Raise impression in small steps and stop at the first setting that fills the tone
Drop viscosity 1 to 2 s DIN 4 with the matched reducer
Condition the film in the press hall in its wrapping until the core reaches hall temperature: typically 24 h for a small reel and 48 to 72 h for a full-width jumbo. Check the core with an infrared thermometer rather than the clock, and do not strip the wrapping while the reel is still cold or it will condense
Replace an impression roller that has gone hard or has flat spots

CONFIRM IT IS FIXED

5 to 15 % tone patches printing with clean dot edges under a loupe at full speed, solid density within 0.05 D of the OK pull at three positions across the web measured to ISO 5-3 with the status stated and on the same backing, and the tone patches within deltaE00 1.5 of the OK pull to ISO 13655, M1, D50, 2 degrees.

THE TRAP

Winding the impression on hard to force the dots in. It flattens the roller, spreads the dot, raises the ink film weight and the retention risk, and the skip returns as soon as the roller recovers or the reel changes.

Solvent Based Gravure InksSpeckle and skipped dots in mid tone (continued)

Fault 5 of 20

Colour to colour misregister and register wander through the run

WHAT YOU SEE

Register is right at the OK pull and walks as the reel builds, or one deck moves in and out on a cycle. It shows first on fine reversed-out text, on a black keyline and where two solids trap, and it is worst in the web direction on thin PET and BOPP.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Web tension changed to cure another faultRegister is held by the length of web between decks. Tension raised at the rewind to stop telescoping, or trimmed at the unwind by hand, stretches or relaxes that span and the mark moves. A good share of the register wander on a gravure press starts as a cure for a soft reel or a blocking reel.
Web heating and stretching through the tunnelsA thin film picks up heat deck by deck and extends, and it does not return the same length as it cools. The error accumulates down the deck order rather than sitting still, so a dryer turned up to chase a soft print is a register change as well as a drying change.
Cylinder diameters or deck temperatures not matched across the setCylinders engraved at different diameters, or one deck running hotter than the rest, deliver different repeat lengths at the same speed, and the register system spends the whole run compensating for a fixed error.
Unwind diameter, a splice or a badly wound reelTension control falls away as the reel empties, and a splice or a telescoped, softly wound reel puts a step into the web that the control has to chase.
A mechanical fault the register system is maskingA worn deck bearing, a slipping drive, a dirty register mark or a marked camera window give the control an error it cannot hold, so it hunts. The error is then periodic at a fixed repeat rather than drifting with diameter.

Solvent Based Gravure InksColour to colour misregister and register wander through the run

Fault 5 of 20 · continued

Colour to colour misregister and register wander through the run

CHECK, IN THIS ORDER

Read the error on the press register system and check it independently on the reel with a loupe and graticule at three positions across the web, against the job's own tolerance, typically 0.1 to 0.2 mm colour to colour on flexible packaging work
Pull the tension profile for every zone at the speed and at the diameter where the error appears, not at the start of the reel, and look for anything that was raised by hand during the shift
Compare the engraved cylinder diameters across the set against the engraving record
Take web and deck temperatures with a probe or an infrared thermometer through the deck order and look for one tunnel running hotter or one dryer recently turned up
Establish whether the error drifts one way with reel diameter or cycles at a fixed repeat; a drift points at tension and heat, a cycle points at a mechanical fault or the mark and camera

THEN CHANGE

Set the tension profile for the film and the gauge and hold it through the reel rather than trimming it by hand
Put the dryer back on its rising profile and cure a soft print at the pan or on speed, not with heat that stretches the web
Take a cylinder that is out of diameter off the job rather than running the set against it
Repair the mechanical fault, clean the marks and the camera window, instead of letting the register system chase an error it cannot hold
Reduce speed where a thin film will not hold register at the tension the reel needs

CONFIRM IT IS FIXED

Register inside the job's own tolerance, typically 0.1 to 0.2 mm colour to colour, checked with a loupe and graticule at the start, the middle and the end of a full reel and at three positions across the web, with the tension profile and the dryer settings unchanged between those checks.

THE TRAP

Pulling register in with tension. It clears the mark on the screen and leaves the web stretched, so the error returns at the next diameter and the reel goes to the rewind with the tension profile that blocks it or telescopes it. Correct the heat and the mechanics; use tension last.

Solvent Based Gravure InksColour to colour misregister and register wander through the run (continued)

Fault 6 of 20

Back-trapping, one colour lifting onto the next cylinder

WHAT YOU SEE

A trailing deck prints dirty and its cylinder and pan pick up the colour of an earlier deck. On the web it shows as a weak, mottled or haloed overprint where two solids cross. It builds through the run rather than appearing at once, and it is worst where a heavy solid was laid early in the deck order.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Inter-deck drying too short for the speedThe first film is still swollen with solvent when the next cylinder touches it, so the film splits at the nip and part of it stays on the chrome.
Blend too slow on the under colourSlow blend added at the first deck to cure drying-in is still in the film at the next nip; the slow fraction is exactly what keeps the film open.
The following ink re-solubilises the film beneath itEster from the next deck attacks a polyurethane or nitrocellulose film that has not yet set, so the two layers mix instead of one laying over the other.
Heavy deposit laid early in the deck orderA solid white or a heavy base put down first is the slowest film to empty and the one most likely to be still open at the next deck.
Inter-deck dryers blanked off or running coldNozzles taped over or a damper shut to save heat removes the only drying the web gets between cylinders.

Solvent Based Gravure InksBack-trapping, one colour lifting onto the next cylinder

Fault 6 of 20 · continued

Back-trapping, one colour lifting onto the next cylinder

CHECK, IN THIS ORDER

Identify which deck the contamination came from by its colour, then check the inter-deck dryer serving the deck before it
Measure the inter-deck air temperature with a handheld probe at the web rather than reading the set point
Check what slow blend has been added at each deck through the shift and on which deck it went in
Run 200 m at half speed and see whether the carry-over stops, which separates dwell from chemistry
Check the deck order against the job; a heavy solid laid early leaves the least drying before the next nip

THEN CHANGE

Restore the inter-deck drying on the deck that is carrying over, and unblank the nozzles
Take the slow blend back down on the under colour and cure the drying-in at the pan instead
Leave a deck empty between the heavy solid and the colour that follows it where the press allows
Reduce the deposit on the under colour by engraving rather than by impression
Reduce speed until the film is set at the next nip, then find the speed back through the inter-deck dryers and not through the ink

CONFIRM IT IS FIXED

2000 m at production speed with the trailing cylinders clean at a stop, the overprint even under a loupe where two solids cross, and no build-up of a foreign colour in any pan at the end of the run.

THE TRAP

Cleaning the contaminated cylinder and carrying on at the same speed. The film beneath is still open, so the same colour is back on the chrome inside another reel, and every clean-down costs more press time than the inter-deck drying would have.

Solvent Based Gravure InksBack-trapping, one colour lifting onto the next cylinder (continued)

Fault 7 of 20

Ink lifts on a tape pull at the press

WHAT YOU SEE

A strip of tape pressed on the fresh print and snapped off takes ink with it. It is usually worse on one film than another, and often worse at the web edges where treatment is weakest.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

The film is not yet dry rather than not adheredA soft, solvent-laden film lifts on tape minutes after printing and recovers 24 h later. It is the cheapest cause to rule out and the one that sends the most false substrate complaints to the film supplier, so it is ruled out first.
Surface energy below the figure for that filmCorona treatment decays in store, so an ink formulated for a treated film is being asked to wet an under-treated one.
Slip additive bloomed to the film surfaceErucamide and similar amides migrate out of BOPP and PE over weeks, and the ink is then sitting on a soap layer rather than on the polymer.
Wrong grade for the filmA surface-print polyurethane-nitrocellulose grade and a metallised grade are built for different interfaces, and neither is a universal ink.
The untreated side of the film is being printedA reel loaded or wound the wrong way presents the untreated face, which reads perfect on a certificate and fails on the press.

Solvent Based Gravure InksInk lifts on a tape pull at the press

Fault 7 of 20 · continued

Ink lifts on a tape pull at the press

CHECK, IN THIS ORDER

Repeat the tape pull on the same print when it is 24 h old before anything else. A print that is not yet empty lifts and then recovers, and until that is ruled out every other check is chasing the wrong fault
Test with dyne inks on the reel you are about to run, at three points across the web including both edges, and both on the outer wraps and after 20 to 30 wraps in
Confirm which face is treated, by dyne test on both sides rather than by the reel label
Check the in-line corona treater is on and read its watt density against the film and the speed
Check the grade in use against the job: 410PU and 415PW for lamination, 450SP for surface print, 460MF for metallised, 470PB for paper and board

THEN CHANGE

Correct the drying and re-test before condemning adhesion
Re-treat in line to the figure for that film and re-test on the running reel: 40 to 42 mN/m on BOPP and PE, 44 to 48 on PET, 44 or above on BOPA nylon
Take a fresher reel where the treatment has decayed or the slip has bloomed, and take it up with the film supplier
Change to the grade that matches the film and the construction
Where treatment cannot reach the level required, put a primer station in rather than reformulating the ink

CONFIRM IT IS FIXED

Tape pull with no ink removal on a 24 h old print at three positions across the web including both edges, with the named test tape recorded, and with the treatment on the reel that was actually run recorded against the figure for that film.

THE TRAP

Blaming the ink and tipping in an adhesion promoter from the store cupboard. An unmatched additive changes the solvent balance and the lamination bond, and nothing put into the ink will make it stick to a bloomed slip layer that a fresh reel would have solved.

Solvent Based Gravure InksInk lifts on a tape pull at the press (continued)

Fault 8 of 20

Laminate bond low, or falls after ageing

WHAT YOU SEE

Peel measured the morning after lamination looks acceptable, but the same structure after a week in the oven has dropped and the plies separate cleanly at the ink, worst through the solid white.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Retained solvent in the printed webSolvent diffuses through the thickness into the adhesive layer over days and plasticises the bond line, so the peel load falls after the pack has been made.
Adhesive coat weight or cure schedule shortAn undercured two-component polyurethane has not built its own cohesive strength, and the ink interface is blamed for the adhesive's shortfall.
Heavy ink deposit, particularly white laid last downThe heaviest film is the slowest to empty and the thickest layer the bond has to pass through, so it is always where the structure fails.
Wrong ink class in a laminateA surface-print grade is built for gloss, slip and jaw resistance, not to carry a bond, so it gives a clean ink-side failure plane.
Treatment wrong on the printed web or on the sealant webThe bond can only be as good as the weakest interface in the stack, and the sealant side is the one nobody tests. Over-treatment counts here too: a polyolefin taken above about 48 to 50 mN/m carries a weak oxidised boundary layer that reads high on a dyne test and peels low.

Solvent Based Gravure InksLaminate bond low, or falls after ageing

Fault 8 of 20 · continued

Laminate bond low, or falls after ageing

CHECK, IN THIS ORDER

Cut and seal a 100 cm2 sample from the printed reel for static headspace GC-FID straight away, so the evidence is preserved and the lab clock is running, then carry on with the free checks below rather than waiting for the result
Peel the unprinted margin of the same laminate. It is the ceiling for anything printed on it, it costs nothing, and it closes most bond complaints in ten minutes
Check the adhesive coat weight against the grade's own figure, 2.0 to 3.0 g/m2 dry general and 3.5 to 4.5 g/m2 dry retort and foil, and the cure record against the adhesive maker's own schedule, together with the age of the laminate at test
Confirm the ink grade on the job and the engraving depth on the white
Measure T-peel through the heaviest deposit, 15 mm strip at 300 mm/min, 23 C and 50 % RH, and record the failure mode with the load

THEN CHANGE

Correct the drying and re-make the laminate before changing anything else
Bring the adhesive to coat weight and let it complete its cure before any judgement is made
Reduce the white deposit by engraving rather than by impression
Move a surface-print job that is being laminated onto 410PU and 415PW
Bring treatment on both webs into the window for each film, floor and ceiling

CONFIRM IT IS FIXED

T-peel through the heaviest deposit after full adhesive cure at or above the 200 g/15 mm design floor, typically 300 to 500 g/15 mm through a process solid and 250 to 400 g/15 mm through the white on a PET 12 micron / adhesive / CPP structure, measured at 15 mm and 300 mm/min with the width and rate quoted, the failure mode reported, and no further drop after ageing.

THE TRAP

Testing the laminate the morning after and signing the job off. The adhesive is not cured and the retained solvent has not finished moving, so the number you measured is not the number the pack will have. The bond you sell is the aged bond.

Solvent Based Gravure InksLaminate bond low, or falls after ageing (continued)

Fault 9 of 20

Odour or taint in the finished pack

WHAT YOU SEE

The customer opens a carton and it smells of solvent, or a bland product picks up a taint on the shelf. The reel smelled clean at the rewind and nothing on the press showed a problem.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Retained solvent in the printSolvent that never left the film before the reel was wound has nowhere to go but into the pack headspace and then into the product.
Flat, hot dryer profileHot air at the entry skins the surface of the ink film in under a second, and once the surface is skinned the solvent below it has no open path out.
Recirculating, saturated dryer air with too little extractionAir already loaded with solvent cannot take up more, so the tunnel is hot but not drying.
Too much slow blend added to cure a drying-in problemThe slow fraction is the hardest to remove and pushes the retention figure up job after job.
Ink film weight too heavy for the tunnel dwell at that speedA thick film has a longer diffusion path to the surface and the same dwell no longer empties it.

Solvent Based Gravure InksOdour or taint in the finished pack

Fault 9 of 20 · continued

Odour or taint in the finished pack

CHECK, IN THIS ORDER

Static headspace GC-FID on 100 cm2 cut from the reel, equilibrated 30 min at 80 C, calibrated against the solvents actually in use, with named species reported separately
Read the dryer profile with the deck thermocouples and a handheld probe at entry and exit, and confirm it rises rather than starting hot
Check the damper position and the LEL reading against the 25 % LEL working limit
Calculate dwell from measured tunnel length and actual running speed, not from the job card
Warm a sample of the reel and smell it as a screening step only, then measure

THEN CHANGE

Set a rising profile, 40 to 50 C at entry to 60 to 80 C at exit, with genuine air turnover
Open the exhaust within the 25 % LEL working limit and clean or replace loaded filters; never hold the tunnel above that limit unless a listed continuous LEL monitor with interlocks is fitted and proved
Reduce line speed until the GC figure is met, then find the speed back through the dryer rather than through the ink
Take the slow fraction back down and solve drying-in at the pan instead
Reduce ink film weight on the heaviest deposit

CONFIRM IT IS FIXED

Not more than 5 mg/m2 total retained solvent by static headspace GC-FID on a sample cut from the running reel, with any named-solvent limit met, repeated at the top speed the job will actually run.

THE TRAP

Turning the dryer temperature up. A hotter flat profile skins the surface faster and locks more solvent underneath, so the print feels drier at the rewind while the GC figure goes up.

Solvent Based Gravure InksOdour or taint in the finished pack (continued)

Fault 10 of 20

Reel blocks, ink picks to the reverse face

WHAT YOU SEE

Unwinding takes a crackling pull and ink has transferred to the back of the film, or the print is matt in bands where the reel was tightest.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Film not empty at the rewindA softened, solvent-carrying film is tacky under pressure and bonds to the reverse face it is wound against.
Winding tension too highPressure between wraps is what converts a soft film into a blocked reel; without it the same film survives.
Reel wound warm and stacked in a hot storeReel stores in North India routinely pass 40 C in summer, and the core of a warm reel does not lose that heat for days.
Surface-print job running without its overprint varnishThe slip that keeps the print off the reverse face lives in UniGrav-490OV, not in the colour.
Overprint varnish itself underdriedA varnish is the heaviest single film on the web and needs the tunnel that the colours needed.

Solvent Based Gravure InksReel blocks, ink picks to the reverse face

Fault 10 of 20 · continued

Reel blocks, ink picks to the reverse face

CHECK, IN THIS ORDER

Run static headspace GC-FID on the reel and settle whether the film is empty
Read reel face and core temperature with an infrared thermometer at the rewind
Pull the tension profile from the press panel and look for a flat rather than tapered profile
Run a hot block test, 24 h at 50 C under 10 kPa for the lamination grades and 40 C for surface-print grades carrying slip
Check the store temperature log and how high the reels were stacked

THEN CHANGE

Complete the drying first; everything else is a workaround
Taper the winding tension to the core
Let the reel cool and stand before it is slit or laminated, and let a laminated reel stand through its cure before it is slit
Stack no more than three reels high on a hot day and let a reel from a hot store equilibrate before unwinding
Specify UniGrav-490OV where the surface-print job needs slip

CONFIRM IT IS FIXED

A sample from the actual production wind held 24 h at 50 C under 10 kPa with no transfer to the reverse face and no gloss change, on the lamination grades, and the same at 40 C for surface print.

THE TRAP

Winding tighter to stop the reel telescoping when the print is soft. Tension is the one thing that turns a soft print into a blocked reel; slow the press or fix the dryer instead.

Solvent Based Gravure InksReel blocks, ink picks to the reverse face (continued)

Fault 11 of 20

Mottled, orange-peel lamination white

WHAT YOU SEE

The white solid looks cloudy and uneven when viewed at a low angle, worst where it lies over a previously printed colour, and opacity reads inconsistently across the web.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

The colour underneath is not dry when the white goes downThe second wet film disturbs a partly set film beneath it, and the two level differently as they dry together.
Viscosity too high for the cell depth on the whiteA heavily pigmented ink at 1.25 to 1.38 kg/l will not level out of a 35 to 45 micron cell if it is also over-viscous.
Surface energy too low on the filmThe ink beads very slightly at the point of transfer, so the solid reproduces the cell pattern instead of flowing together.
Engraving wrong for the inkA cell too fine for a white starves it, and a cell too deep leaves a film that cannot level before it skins.
Blend too fast for the whiteThe heaviest film needs the longest open time, and a blend set for the tone decks skins the white before it flows.

Solvent Based Gravure InksMottled, orange-peel lamination white

Fault 11 of 20 · continued

Mottled, orange-peel lamination white

CHECK, IN THIS ORDER

Check the inter-deck drying between the last colour and the white with a handheld probe at the web
Read pan viscosity on a DIN 4 mm cup at 25 C against the 18 to 22 s target for solids and white
Check the engraving record against 50 to 70 l/cm at 35 to 45 micron
Measure opacity with a spectrophotometer over black and white backing against the standard
Test surface energy with dyne inks on the running reel against the figure for that film

THEN CHANGE

Raise the inter-deck drying for the colour that sits under the white
Hold the white on the correct engraving and bring viscosity down 1 s at a time
Add UniGrav-496SL in small steps where the white is skinning before it levels
Correct treatment and impression before touching the formulation
Leave one deck empty between the last colour and the white where the press allows it

CONFIRM IT IS FIXED

The white solid even under raking light across the full web width, opacity within 2 % of the standard, and bond through the white at or above the design floor on the customer's structure.

THE TRAP

Laying more white on, or adding a second white station, to cover the mottle. That doubles the heaviest deposit in the whole structure, which is exactly where the bond and the residual solvent figure both go wrong.

Solvent Based Gravure InksMottled, orange-peel lamination white (continued)

Fault 12 of 20

Pinholes, crawling and fish eyes in solids

WHAT YOU SEE

Round unprinted spots or comet-shaped voids inside solid areas. They tend to sit in the same lateral positions across the web rather than repeating around the cylinder. Where air is the source the pan carries a head of bubbles, the blade wipes an intermittent film and the solid also prints with a soft leading edge.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Silicone or oil contamination on the filmA silicone spray, a mould release or oil carried in the compressed air puts a low-energy spot on the web that the ink cannot wet and retreats from.
Surface energy too low overallAn ink at the edge of wetting will hold a solid but break around any local defect.
Water in the solvent or in the compressed air lineWater is not a solvent for the resin and forms a discrete phase that leaves a void when it flashes. Reclaimed or reprocessed solvent is a common route for it, as is a drum left open in a humid hall.
Air entrained in the circulation and carried into the cellA return pipe discharging above the ink level entrains air with every litre, and a pump run faster than the deck needs churns the excess. An air bubble filling a cell prints nothing, and a cluster of them prints as pinholes.
Air leak on the suction side of the circulationA loose union or a cracked pipe draws air continuously, so the foam rebuilds however long the ink is allowed to stand.

Solvent Based Gravure InksPinholes, crawling and fish eyes in solids

Fault 12 of 20 · continued

Pinholes, crawling and fish eyes in solids

CHECK, IN THIS ORDER

Wipe the unprinted film with a clean solvent swab and re-test the dyne level on the wiped and unwiped areas
Check the compressed air line at the trap for oil and water, and look for a coalescing filter
Look into the pan at running pump speed for a head of foam, and check whether the return line discharges below the ink level
Watch the suction line for a train of bubbles, which indicates a leak rather than churn, and read the pump speed against what the deck actually needs
Check the reducer drum for water pick-up, particularly a drum left open in a humid hall or a reclaimed batch of unknown history

THEN CHANGE

Change the reel and quarantine the contaminated batch
Fit a coalescing filter on the air line and drain the receiver
Remove aerosol sprays and silicone release from the press hall
Extend and submerge the return line, slow the pump to the lowest flow that keeps the pan full, and seal the suction joints or replace cracked pipework
Take reclaimed solvent, returned ink and additive-loaded ink out of the system and dose only matched reducer

CONFIRM IT IS FIXED

500 m of the same solid free of voids under a loupe at 10x on the film that failed, with a clear ink surface in the pan at running pump speed and a continuous wipe at the blade, after the contamination or the air source has been identified and removed.

THE TRAP

Reaching for an additive. A levelling or slip additive lowers the surface tension of the ink, which can hide the spots on the press and destroy the lamination bond at the same time, and a silicone defoamer is one of the most common causes of craters in the print and of bond failure in the laminate. The fault is almost always a contaminated reel, wet air or plumbing, not chemistry.

Solvent Based Gravure InksPinholes, crawling and fish eyes in solids (continued)

Fault 13 of 20

Two-component ink thickens before the shift ends

WHAT YOU SEE

The 430RT ink climbs on the cup through the afternoon and eventually will not correct. The drum skins over and gel specks show up in the pan and on the blade.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

The pot is simply past its life for the temperaturePot life falls from 6 to 8 h at 30 C to 4 to 5 h at 35 C, and a circulating system runs hotter than the hall, so a pot that was mixed for a shift is spent well before the shift ends.
Hardener over-dosed above 3 to 5 % w/w on weighed inkMore isocyanate crosslinks faster and gels sooner, and the excess does not improve the retort result.
Moisture in the hardener pack or in the solventWater reacts with the isocyanate to give urea, which shows as gel specks and a skin, and CO2, which pressurises a closed pack. Reclaimed solvent is a common route for the water.
The whole shift mixed at the startAn eight-hour pot on a six-hour pot life is a planned failure, and the last two hours print an ink that is already spent.
Alcohol in the ink or in the reducer, which is the silent version of this faultA mono-alcohol such as ethanol caps the isocyanate and terminates the chain instead of building it, so it destroys the retort performance without thickening the pot. The cup reads normal, the print looks right, and the crosslink is simply not in the film. It is found by checking the reducer drum label and the mixing record, not by viscosity.

Solvent Based Gravure InksTwo-component ink thickens before the shift ends

Fault 13 of 20 · continued

Two-component ink thickens before the shift ends

CHECK, IN THIS ORDER

Trend the DIN 4 cup through the shift; pot life ends at a 5 s rise
Take ink temperature in the pan with a probe and compare it to the hall
Check the hardener arithmetic against 3 to 5 % w/w on the weighed ink, not on the pot volume
Check the hardener pack date and whether it has been standing open; a pack suspected of water contamination is vented in a ventilated area, not resealed and returned to store
Confirm the reducer drum is the ester-only version matched to 430RT and that no reclaimed solvent has been drawn on, because alcohol contamination will not show on the cup at all

THEN CHANGE

Mix for four hours of work at a time, not for a shift
Cool the ink drum and the circulation, and keep the deck out of tunnel air
Use only the ester-only reducer once hardener is in the pot, and never reclaimed solvent
Open a fresh hardener pack and buy 1 kg packs so nothing stands open, handling it with nitrile gloves, eye protection and local exhaust
Do not return hardened ink to stock, and do not dilute a thickening pot back into fresh ink

CONFIRM IT IS FIXED

A viscosity rise of not more than 5 s DIN 4 over the intended working period at the actual hall temperature, and the resulting laminate meeting the retort bond and colour targets after full crosslink and full adhesive cure.

THE TRAP

Thinning the thickening ink back to the cup figure and carrying on. The isocyanate is already consumed, so the ink prints and looks right, but the retort performance is not in the film and nobody discovers it until the pouch is in the autoclave.

Solvent Based Gravure InksTwo-component ink thickens before the shift ends (continued)

Fault 14 of 20

Tunnelling or delamination after the autoclave

WHAT YOU SEE

Pouches come out of the retort with channels along the seal or a milky separated area over the print. It is worst over the solid white, at the seal edge and at the gusset crease.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Adhesive not fully cured before processingAn uncured bond line has no reserve to survive the schedule, and the laminate is most often simply too young.
Retained solvent in the printed webAt 121 C the trapped solvent expands and diffuses into the adhesive and sealant plies, and it lifts the ply where the film is heaviest.
Wrong ink class for a retort pack, or hardener under-dosed, dead or capped by alcoholA general lamination grade has no crosslink to hold the interface at 121 C. Without the isocyanate reaction the 430RT film is only a thermoplastic ink with a retort name on the tin.
The trial run before full crosslinkFull crosslink development takes typically 5 to 7 days at 25 C for this system, so a day-one retort test condemns a film that was never finished.
The retort process itself, not the laminateInadequate overpressure, too fast a come-up or cool-down, a water-spray cycle against a steam cycle, and pouches packed tight in the basket will delaminate a sound structure. Every one of these is set on the customer's autoclave, not on the press.

Solvent Based Gravure InksTunnelling or delamination after the autoclave

Fault 14 of 20 · continued

Tunnelling or delamination after the autoclave

CHECK, IN THIS ORDER

Cut and seal a sample from the printed reel for static headspace GC-FID straight away so the lab clock is running, then carry on with the checks below
Peel the unprinted margin of the same laminate; it is the ceiling and it costs nothing
Pull the adhesive cure record, the coat weight against 3.5 to 4.5 g/m2 dry for a retort grade, the hardener addition record and the age of the laminate when it entered the autoclave
Pull the autoclave chart for that batch: overpressure, come-up and cool-down rates, cycle type and how the baskets were loaded
Measure T-peel before and after retort, 15 mm at 300 mm/min, with the failure mode on both, and inspect the crease and gusset under magnification for foil cracking

THEN CHANGE

Hold the laminate for full crosslink and full adhesive cure before any retort test
Correct the drying and re-make the structure
Run 430RT with UniGrav-439HD at 3 to 5 % w/w wherever the pack is retorted, on ester-only reducer
Reduce ink deposit in the seal area at the design stage, and review the crease and gusset geometry with the film and foil supplier where the failure is at a fold
Take the autoclave variables back to the customer's process before anything in the laminate is changed, and qualify the whole construction with their own adhesive, sealant and filled product before a specification is fixed

CONFIRM IT IS FIXED

121 C for 30 min with the product in the pack, then T-peel at or above the 450 g/15 mm design floor with 500 to 800 g/15 mm typical on a PET 12 / foil 7 to 9 / CPP 60 to 80 structure, measured at 15 mm and 300 mm/min with width and rate quoted, no tunnelling, ink lift or blistering at the seal, and seal strength to ASTM F88 within the customer's own acceptance.

THE TRAP

Judging a retort job on a laminate made yesterday. The ink needs typically 5 to 7 days at 25 C to finish crosslinking and the adhesive needs its own cure, so a day-one failure usually tells you nothing except that the pouch was made too early.

Solvent Based Gravure InksTunnelling or delamination after the autoclave (continued)

Fault 15 of 20

Bond or seal fails after a hot fill

WHAT YOU SEE

Pouches filled at 85 to 95 C and held hot show edge delamination, a milky band along the seal or a seal that opens on the filling line, on a structure that passed a retort trial or was never tested hot at all.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Hot fill assumed to be covered by the retort resultA retort qualification is a short exposure under overpressure. A hot fill is a long hold at a lower temperature with the product lying against the seal and the full weight of the contents on the bond line. One does not predict the other.
The seal is made hot and then loaded hotThe sealant is already at fill temperature when the jaw closes, so the seal is formed soft and carries the load before it has cooled and set.
Product wetted into the seal area at fill temperatureOil, sauce or a fatty product at 90 C flows into the seal area and keeps the plies apart, and a dry trial on the same machine reads clean.
Retained solvent in the printA long hot hold gives trapped solvent more time to move into the adhesive and the sealant than a 30 min retort does, so a retention figure that survived the autoclave can still take the bond down here.
Ink and adhesive grades chosen for ambient packsA general lamination construction has no reserve at a sustained hot hold, and the bond line creeps under the load of a full pouch.

Solvent Based Gravure InksBond or seal fails after a hot fill

Fault 15 of 20 · continued

Bond or seal fails after a hot fill

CHECK, IN THIS ORDER

Establish the actual fill temperature and hot hold time from the filling line, not from the specification
Peel the unprinted margin of the same laminate before and after a hot fill trial, so the ceiling is known both ways
Run a hot fill trial with the customer's own product at their own temperature and hold, then measure peel and seal strength on the cooled pouch
Cut a failed pouch and look under magnification for product carried into the seal area
Cut and seal a sample from the printed reel for static headspace GC-FID, and check the age of the laminate when it was filled

THEN CHANGE

Qualify hot fill as its own trial on the customer's product, temperature and hold; do not carry an ambient or a retort result across to it
Keep ink and varnish out of the seal area at the design stage where the construction allows
Move to the hardened 430RT system with UniGrav-439HD where the hot hold is long or the product is fatty
Correct any retained solvent and complete the adhesive cure before the structure is re-trialled
Take the adhesive grade and coat weight back to the adhesive maker with the actual fill condition stated, rather than reducing the ink

CONFIRM IT IS FIXED

Peel and seal strength measured on pouches filled with the customer's own product at their own fill temperature and hot hold, cooled to 23 C, at or above their own acceptance, with peel width and rate quoted and the failure mode recorded, and no edge delamination or seal opening 24 h after filling.

THE TRAP

Signing off a hot fill on the retort data. A 121 C retort for 30 min and a 90 C fill held for an hour are different loads on the same bond line, and a structure can pass one and fail the other.

Solvent Based Gravure InksBond or seal fails after a hot fill (continued)

Fault 16 of 20

Shade shifts or bleeds through retort

WHAT YOU SEE

Reds and yellows go dull or fade after 121 C, or colour appears in the sealant layer alongside the print when the pouch is cut open.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Diarylide yellow or laked rubine red in the shadeDiarylide yellows such as PY12, PY13 and PY83 and laked rubine reds such as PR57:1 are not retort pigments. At 121 C under steam the failure is migration and bleed into the polyolefin sealant, and for the laked reds hydrolysis of the lake, which dulls and shifts the shade. Thermal decomposition is not the mechanism at 121 C, so these pigments must not be qualified on heat-stability data alone.
The shade was built from the surface-print paletteA brand match made for an unlaminated film uses whatever pigment matched, with no constraint on bleed or hydrolysis.
Heavy and prolonged thermal load from a high-temperature schedule135 C work is a different problem from 121 C work and cannot be extrapolated from a 121 C result.
Product attack through the sealantOils, acids, essential oils and surfactants in the filled product reach the ink interface at temperature and over shelf life, and they change what a laminate trial run with water showed at day one.

Solvent Based Gravure InksShade shifts or bleeds through retort

Fault 16 of 20 · continued

Shade shifts or bleeds through retort

CHECK, IN THIS ORDER

Pull the formula card and identify the pigment families in every component of the shade
Measure deltaE00 to ISO 13655, M1, D50, 2 degrees on the laminate before and after retort, on the same backing
Cut the pouch and inspect the sealant face under magnification for colour that has moved
Run the retort with the actual filled product, not with water, and hold filled packs on shelf-life storage as well, because product attack on the bond and the shade can take months to show
Check whether the shade has ever been qualified on this structure or only on a different one

THEN CHANGE

Rebuild the shade on retort-stable pigments, phthalocyanine, quinacridone, benzimidazolone and carbon black
Take the revised shade back to the brand owner where the original cannot be matched inside the stable palette, before the job is scheduled
Qualify shade by shade on the structure that will actually be run, with the actual product
Treat 135 C schedules as their own qualification on the actual pack
Do not let a surface-print match be transferred into a retort job without rebuilding it

CONFIRM IT IS FIXED

deltaE00 not more than 2.0 to ISO 13655, M1, D50, 2 degrees, after 121 C for 30 min against the pre-retort print on the structure that will be run, with no visible colour in the sealant layer, and the same checked again on filled packs held through the customer's own shelf-life trial.

THE TRAP

Matching the brand shade on the press with whatever toner is to hand and then retorting. The match is perfect at the rewind and gone at the autoclave, and by then the shade has to be rebuilt from the pigment up with the whole job waiting.

Solvent Based Gravure InksShade shifts or bleeds through retort (continued)

Fault 17 of 20

Low bond on metallised film, metal transfers

WHAT YOU SEE

Peel on a metallised structure reads low and both separated webs carry aluminium, so the metal layer has split rather than the ink or the adhesive.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Metal-to-polymer anchorage is the weak linkThe vacuum-deposited layer is only as well anchored as the film maker left it, and no ink can exceed that figure.
The unprinted bond of that laminate was never establishedWithout the unprinted margin figure there is no way to know whether the ink cost anything at all.
Wrong grade on metallised workA standard lamination ink can lift or attack a thin metal layer where UniGrav-460MF is formulated to anchor to it.
Retained solvent reaching the metal interfaceSolvent at the metal-polymer boundary weakens the weakest interface in the stack first.
Old or poorly stored metallised reelAn oxidised or aged metallised surface anchors worse than a fresh one, with no visible change.

Solvent Based Gravure InksLow bond on metallised film, metal transfers

Fault 17 of 20 · continued

Low bond on metallised film, metal transfers

CHECK, IN THIS ORDER

Measure T-peel on an unprinted margin of the same laminate first, 15 mm at 300 mm/min; that is the ceiling for any printed area
Measure the printed area on the same geometry and record metal transfer as the failure mode
Check the grade in use is UniGrav-460MF
Run static headspace GC-FID on the printed reel
Check the metallised film's optical density record, age and storage conditions

THEN CHANGE

Run 460MF on metallised and foil work
Set the specification against the unprinted margin of the customer's own laminate, typically 150 to 300 g/15 mm on metallised BOPP and PET at 15 mm and 300 mm/min
Take a low unprinted margin to the film supplier rather than to the ink supplier
Use a fresher metallised reel
Correct any retained solvent before the structure is re-tested

CONFIRM IT IS FIXED

Printed bond within 80 % of the unprinted margin bond on the same laminate, measured at the same width and rate, with the failure mode reported as metal transfer, on the customer's own structure.

THE TRAP

Chasing the ink formulation upward when the unprinted margin peels at the same figure. No ink can exceed the anchorage of the metal it is printed on, and every week spent reformulating is a week the film problem is not being addressed.

Solvent Based Gravure InksLow bond on metallised film, metal transfers (continued)

Fault 18 of 20

Surface print picks off on the seal jaw, scuffs, or runs outside the friction window

WHAT YOU SEE

On an unlaminated surface print the jaw leaves a glossy mark, lifts ink or transfers it onto the jaw face, and the pouching line stops to clean the jaw. The same job can also scuff where reels rub in transit, or slip or grab on the former so the line has to be slowed.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Jaw heat input above what the printed film will takeOn a bare surface print the grade's jaw resistance is a formulation property assessed on the finished film, typically in the region of 160 C at 1 s dwell and 0.2 N/mm2 on the reference construction. It is not a fixed temperature: it falls with longer dwell, higher pressure, thinner film and any retained solvent, and it must be established on the customer's own film and settings.
The matched overprint varnish is missingUniGrav-490OV is formulated to raise jaw resistance and to carry the slip package. Where the job's jaw range runs into the 180 to 200 C region the varnish is part of the specification, not an option, and the working limit is still established on the customer's own film, jaw covering and settings.
Residual solvent leaving the film softA film that is not empty has a lower effective softening point and marks at a temperature it should survive.
Dwell too long or jaw pressure too highHeat input is dwell and pressure as well as temperature, and the three are usually traded against each other without being written down.
Jaw face dirty or the covering worn throughA bare or contaminated jaw grips the print instead of releasing from it.

Solvent Based Gravure InksSurface print picks off on the seal jaw, scuffs, or runs outside the friction window

Fault 18 of 20 · continued

Surface print picks off on the seal jaw, scuffs, or runs outside the friction window

CHECK, IN THIS ORDER

Read the jaw face temperature with a surface probe or a thermal label, not from the controller display
Record the actual dwell and pressure settings on the pouching machine
Confirm whether UniGrav-490OV is specified for this job and whether it is being applied at all stations
Run static headspace GC-FID on the printed reel
Inspect the covering on both jaws

THEN CHANGE

Bring the jaw heat input down where the seal allows, taking dwell and pressure before temperature
Apply the matched overprint varnish and write it into the specification
Re-cover or clean the jaw faces
Complete the drying so the film is at full hardness
Establish and record the working jaw window on the customer's own film, covering and machine, rather than quoting a single temperature

CONFIRM IT IS FIXED

Flat PTFE-faced jaw, one side heated, 1 s dwell at 0.2 N/mm2, tape pull after cooling with the test tape recorded, showing no pick-off, transfer or gloss change at the job's working jaw temperature on the customer's own film and settings; seal strength to ASTM F88 within their acceptance; static and kinetic friction to ASTM D1894 inside their own window, measured on the production wind after the reel has stood; and no scuff against the retained sample at the agreed load and stroke count.

THE TRAP

Dropping the jaw temperature until the pick-off stops. The seal strength goes with it, and a weak seal fails out in the trade where a marked print would have been caught on the line.

Solvent Based Gravure InksSurface print picks off on the seal jaw, scuffs, or runs outside the friction window (continued)

Fault 19 of 20

Comets and spots repeating round the cylinder

WHAT YOU SEE

Small voids or overloaded spots, sometimes with a tail, appearing at a fixed repeat that matches the cylinder circumference. They usually start after the press has stood.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Dried ink skin carried from the drum or the panA flake lodged in or over a cell blocks it or sits proud and prints as a tailed spot until it is dislodged.
Filtration absent, torn or the wrong meshWithout a 100 to 150 micron bag in the circulation every flake goes round again.
Agglomerated pigment from old, settled or badly stirred inkA drum that has stood for months settles hard, and an agglomerate that is not broken down behaves like a hard particle at the blade and at the cell mouth.
Hall debris, paper dust or film shavingsSlitting dust and edge trim find their way onto the web and into the pan on an open deck.
Pitted chromeA damaged cell wall holds ink past the blade and prints the same mark every revolution.

Solvent Based Gravure InksComets and spots repeating round the cylinder

Fault 19 of 20 · continued

Comets and spots repeating round the cylinder

CHECK, IN THIS ORDER

Measure the defect repeat on the web and compare it with the cylinder circumference to prove the source
Inspect the circulation filter bag for holes and confirm the mesh size
Check the drum for a skin and whether anyone has scraped it back in
Strain a sample and inspect it on a fineness of grind gauge, particularly on a stored or returned drum
Examine the chrome with a loupe and a low-angle light

THEN CHANGE

Strain the ink, fit clean filtration and keep drums closed
Never return skin or the scrapings of a drum to the pan, and stir a stored drum to the bottom before it is drawn on
Clean the deck, the web edges and the trim extraction
Where the chrome is pitted, take the cylinder out; if the pitting has reached the copper it must be de-chromed, the copper repaired, re-engraved and re-chromed before it goes back on a job
Wipe the cylinder only with the press stopped, the drive isolated and the blade retracted

CONFIRM IT IS FIXED

1000 m at production speed with no defect repeating at cylinder circumference, and a clean, intact filter bag at the end of the run.

THE TRAP

Wiping the cylinder with a rag while the press runs. It puts lint into the cells, scores the chrome behind the blade, and puts a hand next to a doctor blade at speed for a defect that a two-minute stop would have cleared properly.

Solvent Based Gravure InksComets and spots repeating round the cylinder (continued)

Fault 20 of 20

Static: misting, dot scatter and shocks

WHAT YOU SEE

A haze of ink around solids, dots scattered outside the image, crackling at the web, and operators taking shocks at the rewind. It is worse in a dry hall in winter.

WHAT IT LOOKS LIKE

CAUSES, MOST LIKELY FIRST

Hall relative humidity too lowDry air lets charge build on PET and BOPP faster than it can leak away, and the electrostatic assist then works against an uncontrolled field.
Static bars off, dirty or wrongly positionedA dusty bar or one sited too far from the web does nothing, and nobody notices because it fails silently.
Web earthing or frame bonding brokenAn isolated roller becomes a charged conductor and discharges to whatever comes near it, including an operator.
High line speed on a charging filmCharge generation rises with the separation rate at every nip and unwind.
Electrostatic assist wound up to compensate for a poor nipExcess assist field adds to the charge on the web instead of curing the transfer problem it is being used to mask.

Solvent Based Gravure InksStatic: misting, dot scatter and shocks

Fault 20 of 20 · continued

Static: misting, dot scatter and shocks

CHECK, IN THIS ORDER

Read hall relative humidity with a hygrometer; 45 to 60 % is the working range
Take static field readings at the unwind, at each deck and at the rewind with a field meter
Inspect the static bars for dust and confirm each has a live supply
Test earthing and bonding continuity on rollers and frame, including the earth and bond points required in a flammable-liquids area
Check the electrostatic assist setting against the press maker's figure rather than against habit

THEN CHANGE

Restore humidity in the hall
Clean, re-position or replace the static bars
Repair earthing and bonding before anything else, because this is a safety fault first
Reduce speed where the charge cannot be brought under control
Fix the impression nip and bring the assist back to its correct setting

CONFIRM IT IS FIXED

Static field readings inside the press maker's limits at running speed, print free of scatter and misting under a loupe, and earthing and bonding proved by a continuity test with the result recorded.

THE TRAP

Living with it, or wetting the floor to knock it down. In a Class A petroleum area with ester and alcohol vapour present, a static discharge is an ignition source before it is a print defect, and it must be treated as a safety fault, not a quality one.

Solvent Based Gravure InksStatic: misting, dot scatter and shocks (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
Highlights screening out, cylinder drying-in	Pan viscosity on a DIN 4 mm cup at 25 C, and ink temperature with a probe	Slow blend with UniGrav-496SL in 5 % steps, then set viscosity with the matched reducer
Colour drifting reel to reel	Viscosity log and whether the automatic unit is dosing the matched reducer	Cover and recirculate the pan, set automatic dosing every 30 to 60 s, stop hand toning
Streaks and lines down the web	Blade edge under a loupe with the press stopped and the blade retracted, and the circulation filter bag	Index or change the blade, clean the seat, fit filtration; do not add pressure
Speckle, dots skipping in mid tone	Electrostatic assist reading at the panel and hall relative humidity	Restore the assist, then impression in small steps, then viscosity down 1 to 2 s
Misregister and register wander through the run	The tension profile for every zone at the diameter where the error appears, and whether anything was raised by hand this shift	Put the tension profile and the dryer back where they belong before touching register; never pull register in with tension
Back-trapping onto a following cylinder	Which deck the colour came from, and the inter-deck dryer serving the deck before it	Restore inter-deck drying and take the slow blend back down on the under colour
Ink lifts on a tape pull at the press	Repeat the tape pull on the same print at 24 h before anything else; then dyne inks on the reel, both faces, both edges, outside and 20 to 30 wraps in	Correct the drying first; then re-treat to the figure for that film or change to a fresher reel
Bond low or falling after ageing	Peel the unprinted margin of the same laminate and read the adhesive coat weight and cure record; cut and seal the GC sample at the same time	Let the adhesive complete its cure, correct the dryer profile, and re-test before changing the ink

Solvent Based Gravure InksQuick reference

Quick reference

One page at the press

Symptom	Check this first	Change this first
Odour or taint in the pack	Static headspace GC-FID, 100 cm2, 30 min at 80 C	Set a rising dryer profile with the exhaust open within 25 % LEL, then reduce speed
Reel blocking, ink on the reverse face	Reel core temperature and the winding tension profile	Complete the drying and taper the tension; let the reel stand before slitting
Mottled or orange-peel white	Inter-deck drying under the white and the engraving spec	Raise inter-deck drying and hold the white on 50 to 70 l/cm at 35 to 45 micron
Pinholes, fish eyes and voids in solids	Solvent swab wipe test on the film, the compressed air trap for oil and water, and the pan for a head of foam	Change the reel, fit a coalescing filter, submerge the return line and slow the pump; no defoamer
Two-component ink thickening in the pot	How long the pot has been mixed against the temperature, then the hardener arithmetic at 3 to 5 % w/w on weighed ink	Mix for four hours of work, cool the circulation, use only the matched ester-only reducer
Tunnelling or delamination after retort	Age of the laminate when it entered the autoclave and the adhesive cure record, plus the autoclave chart	Hold for full crosslink and full adhesive cure, then re-test before changing the ink
Bond or seal failing after a hot fill	Actual fill temperature and hot hold time from the filling line, and whether hot fill was ever trialled	Run a hot fill trial with the customer's own product and hold; do not read it off the retort data
Shade shifting through retort	Pigment families on the formula card	Rebuild the shade on retort-stable pigments; do not correct it on the press

Solvent Based Gravure InksQuick reference

Quick reference

One page at the press

Symptom	Check this first	Change this first
Low bond on metallised film, metal transferring	T-peel on the unprinted margin of the same laminate first, at 15 mm and 300 mm/min	Set the specification against the unprinted margin; take a low margin to the film supplier, not to the ink supplier
Pick-off on the seal jaw, scuffing, or friction out of window	Jaw face temperature with a surface probe, not the controller display, with dwell and pressure recorded; friction to ASTM D1894 on the production wind	Apply UniGrav-490OV and put it in the specification; reduce dwell and pressure before temperature
Comets and spots repeating round the cylinder	The defect repeat measured against the cylinder circumference, and the circulation filter bag	Strain the ink, fit clean filtration and keep drums closed; wipe the cylinder only with the press stopped
Static: misting, dot scatter and shocks	Hall relative humidity, and earthing and bonding continuity on the rollers and the frame	Repair earthing and bonding first, because this is a safety fault; then humidity, the static bars and the nip

Solvent Based Gravure InksQuick reference

Test methods

The measurements this guide relies on

Measurement	Method	What it tells you, and the usual acceptance
Flow cup viscosity	DIN 4 mm cup, DIN 53211 geometry. ISO 2431 flow cups are a different geometry and a different test temperature, and their seconds are not interchangeable	The working control for transfer and film weight. Sample and cup at 25 +/- 1 C, drawn at the pan. Typical acceptance: 15 to 18 s on 70 to 110 l/cm tone work, 18 to 22 s on 50 to 70 l/cm solids and lamination white, 16 to 20 s on surface-print line work. Quote the cup and the temperature with every reading; a DIN 4 second is not an ISO 4 second and neither is a Ford B4 second. If the plant works on an ISO cup, re-establish these targets on that cup before using them.
Retained solvent by static headspace gas chromatography	Static headspace GC-FID, run to the converter's or brand owner's written protocol; no single standard number is cited here	The only honest answer on drying. 100 cm2 cut from the running reel, sealed at once so the sample does not off-gas on the way to the lab, equilibrated 30 min at 80 C, calibrated against the solvents actually in use, named species reported separately. Typical acceptance for laminated food-contact work: not more than 5 mg/m2 total, with 1 mg/m2 on a named solvent where a brand owner sets one.
Laminate bond, T-peel	In-house T-peel, 15 mm strip at 300 mm/min. ASTM F904 and ISO 11339 each specify their own specimen width and rate, so a figure from either is not interchangeable with a 15 mm result and the method must be stated with the number	Whether the pack holds together. 15 mm strip, crosshead 300 mm/min, 23 C and 50 % RH, after the adhesive has fully cured. Report the mean plateau load in g/15 mm with the failure mode against it, and quote the width and the rate every time. Peel load is not linearly transferable between widths or speeds, so never convert a 15 mm figure to a 25.4 mm one or compare results taken at different crosshead speeds. Typical: 300 to 500 g/15 mm through a process solid and 250 to 400 g/15 mm through the white on PET 12 micron / adhesive / CPP; design floor 200 g/15 mm general and 450 g/15 mm retort, both read against the unprinted margin of the customer's own laminate.
Wetting tension	ASTM D2578 and ISO 8296 are written for polyethylene and polypropylene film; on PET and nylon the reading is comparative and the acceptance limit is set per film	Whether the film will take the ink today. Applied on the reel at the unwind, at three points across the web including both edges, and both on the outer wraps and after 20 to 30 wraps in. Acceptance: BOPP and PE not below 38 mN/m with 40 to 42 preferred, PET not below 42 mN/m with 44 to 48 preferred for reverse-print lamination, BOPA nylon not below 44 mN/m; on polyolefins do not exceed about 48 to 50 mN/m, because over-treatment leaves a weak oxidised boundary layer that reads high here and peels low in the laminate. Handling: the classical test mixtures contain formamide and 2-ethoxyethanol, which are reproductive toxicants, so use formamide-free inks or pens where available, wear nitrile gloves, avoid skin contact and keep the fluids off the running web path. A film supplier's certificate is not a substitute for a test on the reel.
Adhesive tape pull	No standard number cited; the method is described. ASTM D3359 and ASTM D3330 both exist but describe different geometries from this snap-off, so the tape, the contact and the removal are specified here instead	The quick adhesion screen at the press. The result is decided almost entirely by the tape, so use one named high-tack test tape, 25 mm wide, and record which one with the result; a result from a different tape is not comparable. Press it down with uniform pressure, leave it 60 s, then remove it sharply at close to 180 degrees. Acceptance: no ink removal, on a print at least 24 h old as well as on a fresh one, since a print that is not yet empty will lift and then recover.
Colour difference	ISO 13655, M1 illumination, D50, 2 degree observer, deltaE00	In-run colour control and retort stability. Measured on the same backing each time. Typical acceptance: deltaE00 not more than 1.5 between the OK pull and hourly pulls through the run, and not more than 2.0 after 121 C for 30 min against the pre-retort print.
Solid density	ISO 5-3 for the spectral conditions; state the measurement status, T or E as the plant uses	The in-run film weight check on solids, read alongside deltaE00 rather than instead of it. Read on the solid and not on a tone patch, because a mid-tone density reading is dominated by dot area rather than by film weight. Typical acceptance: solid density within 0.05 D of the OK pull at three positions across the web, on the same backing, with the status quoted.

Solvent Based Gravure InksTest methods

Test methods

The measurements this guide relies on

Measurement	Method	What it tells you, and the usual acceptance
Seal strength	ASTM F88	Whether the pack seals as well as it prints. Used alongside jaw resistance work so that a jaw setting changed to cure ink pick-off is not quietly costing seal strength, and repeated on hot-filled packs after they have cooled. Acceptance is the customer's own for the pack and the product.
Coefficient of friction	ASTM D1894	Machinability of surface-printed and varnished reels on the pouching or form-fill-seal line. Static and kinetic values, print face to film back, measured on the production wind rather than on a hand proof and repeated after the reel has been stored, because slip develops with time. Acceptance is set by the customer's machine; the figure comes from UniGrav-490OV and the slip package, not from the colour.
Rub and scuff resistance	No standard number cited; the method is described. Run on a Sutherland-type rub tester at a stated load and stroke count	Whether a surface print survives handling and transit. Printed face against the film reverse or against itself, a stated load and number of strokes, on a print at least 24 h old, judged against a retained sample rather than by opinion. Acceptance is agreed with the customer for the pack and the journey; the resistance comes from UniGrav-490OV and its film weight, not from the colour.
Blocking, hot block test	No standard number cited; the method is described	Whether the reel will survive the store. Printed face against film reverse, 24 h at 50 C under 10 kPa for lamination grades and at 40 C for surface-print grades carrying slip. Acceptance: no transfer to the reverse face and no gloss change, on a sample taken from the actual production wind.
Migration and sensory assessment	No conformity claimed here; assessment is on the finished pack, by the party that owns the pack specification	Raw materials for these series are selected to the EuPIA Exclusion Policy and the exclusion list, and the lamination grades are formulated without the substances the Charter excludes. That is a formulation statement, not a conformity statement. Migration and sensory performance are properties of the finished pack, because they depend on the ink, the structure, the ink deposit, set-off in the reel, the product and the storage. A migration or sensory position is established on the converter's actual construction and filled product, by the brand owner's or converter's own assessment, and UF will support that assessment with the formulation data required. Where set-off is the concern, it is assessed on the reel as wound, not on a hand proof.

Solvent Based Gravure InksTest methods

When the press-floor fixes have not worked

What to send us

A sample of the reel as printed, at least 2 m, wound print-side out, sealed in a barrier bag and labelled with the job, the deck order, the running speed and the time it was taken, so residual solvent can be measured on what actually ran rather than on a proof that has been open to the air.
The laminate itself and the unprinted margin of the same laminate, with the adhesive named, its coat weight in g/m2 dry and the cure schedule and dates, so the unprinted bond can be established as the ceiling before the ink is discussed.
Peel results you already have, in g/15 mm with the failure mode against each one, plus the strip width, the crosshead speed and the age of the laminate at test. A load without its failure mode cannot be interpreted, and a load without its width and rate cannot be compared with anything.
The press log for the run: pan viscosity readings through the shift with the cup type stated, ink temperature, dryer entry and exit temperatures, damper position and LEL readings, line speed and winding tension, plus which reducer drums were opened and whether any of them was reclaimed solvent.
The film specification and its treatment history: supplier, grade, thickness, date of manufacture, date of receipt, storage conditions, and the dyne readings taken on the reel at the unwind, on the outside and 20 to 30 wraps in and at both edges, rather than the certificate figure.
For a two-component job, the hardener batch and pack date, the addition in % w/w on weighed ink, the time the pot was mixed and the time it was still being used, and whether any solvent other than the matched ester-only reducer was added at any point.
For a retort failure, the retort schedule with the autoclave chart, the overpressure and the come-up and cool-down rates, the actual product in the pack, the age of the laminate when it entered the autoclave, and at least six failed pouches uncut, so the failure location can be found before anything is opened.
For a hot-fill failure, the actual fill temperature and hot hold time from the filling line, the product, the age of the laminate when it was filled, and at least six failed pouches uncut and unemptied.
For a register complaint, the reel with the fault marked and the metres noted, the job's own register tolerance, the cylinder set with its engraved diameters, the tension profile for every zone at the diameter where the error appeared, the line speed and the dryer settings in use at the time.
For a machinability complaint, whether it is rub, scuff or friction: the window the customer's machine needs, the static and kinetic values measured on the production wind to ASTM D1894, the age of the reel when it was run, whether UniGrav-490OV was applied and at what film weight, and a metre of the reel as wound.

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Solvent Based Gravure InksTechnical service