Lamination Services
Adhesion Failure and Delamination: Why the Film Won’t Stick
Adhesion failure is the expensive defect, because it usually shows up after the job has left. The sheets looked fine off the laminator. They looked fine at the trimmer. Three days later the customer calls because the corners are lifting on 4,000 folders.
Sometimes a job that initially appears to be of good quality will begin to peel or come apart once the laminate has set, because the adhesive backing on the laminate is not able to maintain a strong bond with the substrate — and a variety of factors can result in a weak bond.[1]
This article works through those factors in the order you should check them, and it deliberately spends most of its length on the chemistry, because that is where the failures a machine adjustment cannot fix actually live.
1. First: is it heat, pressure or time?
Before you go looking for exotic causes, rule out the process window. Unless there is an issue in the quality of the laminate — something that should be validated through a trial run prior to live jobs — the likely cause of poor adhesion is an adhesive that is not warm enough, so the first move is to increase the heat of the roller.[1]
Then check speed, because this is the one operators most often overlook: even when a laminate receives acceptable levels of heat and pressure, a high run speed may prevent the adhesive from softening enough to adhere properly to the substrate. A strong bond requires a combination of heat, pressure, and time, and especially for thicker films, slowing the run speed may be necessary to give the adhesive layer enough time to absorb heat from the roller.[1]
Inadequate or uneven pressure and too much speed cause bonding problems in the same way inadequate heat does.[2]
If the bond is uniformly weak across every sheet in the run, it is usually process. If it is weak only in specific areas — over certain colours, at the trim edge, on one stock and not another — it is chemistry, and the rest of this article applies.
2. Ink: the largest single cause category
2.1 Wet ink
One of the most important rules of thumb in thermal lamination is to always let ink dry completely before applying a laminate, because wet ink can cause bubbles and condensation to form between the substrate and the laminate.[1]
Slow-drying inks are a specific hazard, and heavy coverage makes them worse. Slow drying inks are usually not completely dry before they are coated — particularly true with multiple overprints and areas of heavy ink coverage — and slow drying inks release vapours as they dry, which interferes with bonding and can be aggravated by the heat of the curing unit.[5]
The thermal mechanism deserves stating because it explains why “it was nearly dry” is not good enough: when running a laminator at 85°C, the point where the rolls sit together can easily become a hot spot of over 95°C, and when a moist inkjet print encounters one of these hot spots the ink can boil, creating bubbles.[2]
2.2 Ink chemistry by press type
Compatibility is not uniform, and knowing where your press sits saves a lot of testing.
Runs on standard adhesive: conventional offset and flexographic inks are compatible with most types of adhesives, and some digital inks such as HP Indigo inks are also able to bond with standard laminates.[1] The reason Indigo works is structural — those inks still include toner powder, but the powder is suspended in imaging oil, preventing it from directly touching the adhesive and enabling the average thermal laminate to form a strong bond.[8]
Also broadly compatible: Canon VarioPRINT i/iX-series presses using aqueous inkjet, Canon V1000 electrostatic ink, Canon ImagePRESS T01 and T02 toner, and the Fujifilm JPress aqueous inkjet platform.[8]
Needs a high-strength adhesive: many digital alternatives such as UV inkjet, fuser oils and toner-based inks require superior-strength adhesives.[1]
Test before you commit: Nobelus recommends sending sheets for testing when the press is made by Kodak, Komori, Konica, Ricoh, Xeikon or Xerox — these do not have the same consistency and reliability as the HP, Canon or Fujifilm systems, though there is always a chance they will work, and many variables from humidity and run speed to elevation and time of year affect how well thermal adhesives work with a given digital ink.[8]
The historical reason for the digital problem is worth understanding, because it explains why the picture keeps changing: digital press manufacturers historically used dry toner, giving inks a waxy quality that prevented them adhering well to the thermal adhesives typically used on laminates, since compatibility with lamination was not a priority in their development.[8] Newer formulas are much more likely to adhere to the average thermal laminate — but the old rule of thumb is now less accurate rather than reversed.[8]
Chicago Laminating states the practical conclusion for buyers: some standard laminates may not adhere well to toner, leading to delamination or peeling, so digitally printed sheets require a laminate specifically designed for digital printing that offers superior toner adhesion.[5]
2.3 Waxes, Teflon and fountain solution
Rub-resistance additives are adhesion-killers. Inks have waxes or Teflon in them to give them greater rub resistance, and the wax or Teflon acts much like wax on a car, causing the coating to bead up and not stick to the ink.[5]
Fountain solution chemistry contributes as well: many alcohol substitutes contain glycol that interferes with bonding, and the fix is to use an alcohol substitute that does not contain glycol, or to replace the substitute with alcohol.[5]
VOC level is the fourth ink factor. Inks that are to be coated need a low-VOC formulation — low VOC inks, also called High Solid inks, have VOCs below 10%.[5]
2.4 Metallic inks — the failure you should refuse before you run it
This is the one case where the correct answer is often “don’t.” The mechanism is specific and it is worth quoting to a customer who insists.
Metallic inks are normally manufactured from raw metal milled into flat platelet-type particles, and to ensure an acceptable degree of lustre the layers of metal particles must remain separate after the ink is laid down — which is achieved by adding a stearate type lubricant to the metal particles during the milling process.[5]
That creates two independent failure paths:
- Lubricant migration. The lubricant added in the manufacturing process can migrate to the surface as the ink dries, and during the lamination process the adhesive is unable to bond to the lubricant on the surface, resulting in poor adhesion.[5]
- Cohesive failure inside the ink film. More prevalent is the poor cohesive binding of the metal particles in the ink: when the ink is UV coated or laminated, adhesion only occurs on the surface or top layer of the metal particles.[5]
The second path is the important one, because no adhesive can fix it. The bond between film and ink can be perfect and the job still fails, because the ink film tears itself apart internally. Laminated inks, especially where the metallic ink bleeds over the trim, will delaminate when subjected to stress.[5]
There is a workaround with a cost: there are metallic inks that can be coated or laminated, but due to compromises in the manufacturing process they do not have the same degree of lustre and are sometimes referred to as “simulated” metallics.[5]
Design guidance to give the customer up front: keep metallic ink away from the trim edge. That is where stress concentrates and where delamination starts.
2.5 Ink coverage
Coverage changes the bond-strength requirement, and it is why the same film passes on one job and fails on the next. Ink coverage affects bond strength: text-based prints with few graphics require less adhesive strength than a sheet completely covered with a solid layer of ink.[1]
2.6 UV-cured offset ink and reverse-transfer failure
An unusual failure mode worth naming because it confuses diagnosis: with UV-cured offset ink, layers of ink can be removed when thermal laminate is applied and then peeled off. If the bond between the UV-cured ink and the substrate is weaker than the bond between the laminate film and the ink, the ink may be pulled off when the laminate is removed.[5] Ink film thickness contributes — if the ink layer is too thick it may not fully cure during UV curing, leaving a soft or tacky surface that the laminate lifts.[5]
In this case the laminate is not failing. The ink’s anchorage to the paper is.
3. Spray powder: the invisible contaminant
Anti-set-off spray powder does a necessary job on press and can quietly destroy the finishing operation downstream.
Powder is generally made from natural starches from plants and vegetables, and its diameter is chosen relative to the density of the stock being printed — for 150 g/m² paper the ideal powder is 15 μm in diameter, for 200 g/m² it is 20 μm, through to 70 μm for heavy 700 g/m² board.[7]
Most manufacturers offer both coated and uncoated grades. Uncoated powders are generally less expensive and are based on natural food-grade starches; coated powders use the same raw materials but are encapsulated with a minuscule amount of natural coatings so they flow freely through the spray guns, and enhanced versions of those coatings are used to give specific electrostatic (anti-static) and hydrophobic properties.[7]
Those hydrophobic coatings are what break lamination. Silicone-coated powders cannot be used when foil stamping or laminating, and over-use of spray powder, or too large a particle size, causes problems when laminating, coating or varnishing.[6]
Two things follow for a print shop:
- Specify the uncoated grade on any job that will be laminated, foil stamped, coated or varnished.
- Reduce the amount, and size it to the stock. Over-use is called out as a distinct problem independent of the coating type.[6]
Note also which processes don’t use it at all — spray powder is not generally used in sheet-fed screen printing, ink-jet or toner-based digital printing, and not on rotary presses including web offset, flexo or gravure.[7] If you are receiving powder-related failures, the source is your sheet-fed offset work.
4. Surface energy: the measurable version of “will it stick”
For film substrates and non-absorptive surfaces, adhesion is not a matter of opinion. It is a number.
The ability of a substrate to anchor inks, coatings, or adhesives is directly related to its surface energy: if the substrate surface energy does not significantly exceed the surface tension of the fluid which is to cover it, wetting will be impeded and a poor bond will result.[9] The benchmark levels are published — for most solvent-based printing, plastics need to be treated to 36 to 40 dynes/cm; water-based inks usually require 40 to 44 dynes/cm; and some laminating and coating applications require surface energies of 50 dynes/cm or more.[9]
In web lamination practice the working floor is stated as a rule: treat both webs at or above 40 dyne/cm, and even if film is fresh, “bump treating” in line will help to clean the surface and promote better flow, levelling and adhesion.[10]
The measurement method is standardised. The dyne test uses solutions of 2-ethoxyethanol and formamide to determine wetting characteristics, and the cotton swab method complies fully with ASTM D2578 and ISO 8296.[9] The read is timed: note how long it takes from application until the solution beads up, and the level which comes closest to wetting the surface for exactly two seconds is the material’s surface energy in dynes/cm.[9]
Three practical cautions from the method itself:
- Treatment decays. The surface energy of treated films can drop dramatically over a very short period of time just after treatment, so the elapsed time from coating to test — and from test to printing — must be controlled.[9] This is the same reason laminate shelf life is calculated from date of manufacture rather than delivery, and why corona-treated films begin losing surface energy immediately.[30]
- Contamination invalidates the result. Do not touch or in any way contaminate the surface to be tested; dirty surfaces lose their wettability.[9]
- Surface energy is not the whole answer. It is critically important to many printing and converting operations but is not the sole determinant of product suitability — surface topography, coating rheology and chemical incompatibility must also be considered.[9]
Note that the dyne test is designed for plastic films and other non-absorptive substrates, and it is explicitly unreliable on paper: if the test fluid permeates a fibre substrate such as paper and causes swelling, results will indicate unrealistically easy wetting.[9] For paper lamination, surface energy thinking belongs to the film side and to coated or synthetic stocks — not to a dyne pen on an uncoated sheet.
5. Stock
Everything from the thickness and texture of paper stock to its acid content can affect its ability to bond with a given thermal laminate — construction paper, for example, has a higher acid content than standard copier paper and requires stronger adhesives for quality results.[1] Nobelus’s diagnostic advice is direct: if no other solutions work, the issue may lie in the type of paper stock that is paired with the laminate.[1]
Rough stock also interacts with film gauge. Combining thin films with rough paper can leave too little adhesive to fill all the pockets on the paper.[1] The result is usually silvering, but on a heavily handled piece it becomes a peel failure over time.
6. Priming and pre-coating
Two questions come up constantly on the trade counter.
Can I aqueous coat in-line before laminating? An in-line aqueous “primer” has been proven to work successfully in most applications, but it is always recommended that testing be done to determine compatibility prior to running.[5]
Why can’t UV coating go on uncoated stock? Because uncoated stock is porous and tends to absorb liquids including UV coating — the coating may penetrate the paper fibres unevenly, resulting in a blotchy or inconsistent appearance and poor adhesion.[5] Curing suffers as well, since uncoated stock does not reflect UV light efficiently, which can leave the coating tacky, smudging or poorly durable.[5] Nobelus states the same limit from the other side: UV coating should only be applied to coated paper stocks, because uncoated stock absorbs the liquid before it cures.[19]
Film lamination does not share this restriction, which is one of the reasons it is specified over UV for uncoated work.
For toner prints, standard UV coating has its own known failure: digital toners, especially oil-based, have low surface energy and resist adhesion, causing coatings to sit on top rather than bond, and many digital printers use silicone or fuser oils in the fusing process which act as a barrier to UV coatings.[32]
7. Delamination that shows up late
Some failures are not present at the laminator at all. Laminate or package performance issues may occur early in the process or not show up until the product has been in service for some time, and issues can be low bond or peel strength, poor heat resistance, tunneling, or delamination after exposure to the environment.[10]
When you do get a failed sample back, read the failure mode before you change anything. It is important to understand the mode of failure in the defect, because it narrows the root cause: is the void caused by ink or adhesive split? Is the adhesive releasing from the ink, or is the ink decaling from the primary web? Is the adhesive releasing from the secondary substrate?[10]
That three-way distinction maps directly onto three different fixes:
| Where it separates | What failed | Fix direction |
|---|---|---|
| Adhesive lets go of the ink | Bond strength or surface chemistry | Stronger adhesive; remove wax/silicone contamination[1][5] |
| Ink lifts off the paper with the film attached | Ink anchorage, not lamination | Ink curing, ink film thickness, press-side fix[5] |
| Ink film splits internally | Cohesive failure inside the ink — classic metallic | Change the ink; no adhesive fixes this[5] |
8. Measuring the bond instead of arguing about it
If bond strength is genuinely in dispute — between you and a supplier, or you and a customer — there is a standard test for exactly this geometry.
ASTM D1876, commonly called the T-peel test, determines the peel strength of a bonded assembly made from two flexible materials, named for the T shape the specimen forms as the two ends are pulled apart.[25] The method: two flexible substrates are bonded, the unbonded ends are bent back and clamped into opposing grips of a universal testing machine, the machine pulls the grips apart at a constant rate, and the average force recorded during the stable peeling portion is reported as force per unit width, such as pounds-force per inch or Newtons per metre.[25]
It is distinct from ASTM D903 (180-degree peel), which typically involves peeling a flexible material from a rigid one; T-peel is purpose-built for scenarios where both materials have a degree of flexibility.[25] Manufacturers use the T-peel test as a consistent quality control check to ensure that production runs of bonded materials meet required strength specifications, and it can reveal how factors like adhesive thickness, curing time or surface preparation affect final bond strength.[25]
Most trade shops will never run a universal test machine. The value of knowing the standard exists is in the conversation: a film supplier who cannot give you a peel value on your substrate is selling you a guess.
9. Prevention checklist
At quoting
- Ask what press and ink system printed the sheet. Offset, flexo and HP Indigo bond with standard adhesives; UV inkjet, fuser oils and toner-based work need superior-strength adhesive.[1][8]
- Flag metallic ink, and flag it hardest where it bleeds over the trim.[5]
- Flag heavy solid coverage — coverage raises the bond-strength requirement.[1]
- Flag rub-resistant inks containing wax or Teflon.[5]
At the press
- Specify uncoated spray powder, sized to the stock, and use as little as will do the job.[6][7]
- Use low-VOC (High Solid) inks, below 10% VOC, on work that will be coated.[5]
- Avoid glycol-bearing alcohol substitutes in the fountain solution.[5]
- Leave ½″ trim on all four sides so the laminate does not encroach on the printed copy, never hangs off the sheet edge, and gripper and side guide stay clean for downstream registration.[5]
Before lamination
- Let ink dry completely — not dry to the touch.[1]
- Consider deliberate dwell time. Waiting at least half a shift or even a whole shift before running digital prints through the laminator vastly increases the likelihood of a standard thermal laminate adhering to digital inks.[8]
- Consider an IR heater for problem inks. Adding an IR heating system enables the machine to evaporate certain components of the digital ink that prevent adhesion, and these units cost a fraction of a percentage of the total cost of a thermal laminator.[8]
Always
- Trial-run any new material combination without exception.[1] Incompatibility among components can adversely affect the ability of the overlaminate to adhere and result in delamination — so test, don’t guess, and when you find a winning combination, stick with it.[3]
Send us the hard ones
Adhesion problems are where a trade laminator earns its keep, because we have already run the ink systems, stocks and film combinations that a general print shop meets once a year.
Lamination Services has laminated for the print trade since 1998, out of Salado, Texas — 1.5 mil to 10 mil, gloss or matte, up to 27 inches wide, any length.[35] If you have a metallic-ink job, a heavy-coverage digital run, or a stock you have never laminated before, call before you print it.
Sam — (254) 290-6337, Monday to Friday.
Sources
[1] https://nobelusuniversity.com/2023/10/26/troubleshooting-tips-for-thermal-lamination — Nobelus University — Troubleshooting Tips for Thermal Lamination [2] https://postpressmag.com/articles/2015/common-issues-in-laminating — PostPress Magazine / MACtac — Q&A: Common Issues in Laminating [3] https://blog.nekoosa.com/laminating-tips-silvering — Nekoosa / RTape (Jim Hingst) — Laminating Tips: Silvering [5] https://www.chicagolam.com/faqs — Chicago Laminating — Frequently Asked Questions [6] https://corkindustries.com/5-spray-powder-usage-concerns — Cork Industries — 5 Spray Powder Usage Concerns [7] https://en.wikipedia.org/wiki/Anti-set-off_spray_powder — Wikipedia — Anti-set-off spray powder [8] https://nobelusuniversity.com/2024/03/21/a-quick-guide-to-thermal-lamination-and-challenging-digital-inks — Nobelus University — Thermal Lamination and Challenging Digital Inks [9] https://www.accudynetest.com/qctest.html — Diversified Enterprises / Accu Dyne — Using the Dyne Test to Measure Polymer Surface Energy [10] https://www.laminatingadhesiveproducts.com/technical-articles/finding-the-root-cause-of-your-adhesion-issues — ChemPoint / Laminating Adhesive Products — Finding the Root Cause of Your Adhesion Issues [19] https://nobelusuniversity.com/2023/02/03/how-to-choose-a-finish-lamination-vs-uv-coating — Nobelus University — How to Choose a Finish: Lamination vs UV Coating [25] https://www.adhesivesresearch.com/Insights/astm-d1876-the-standard-for-t-peel-strength-in-adhesives — Adhesives Research — ASTM D1876: The Standard for T-Peel Strength in Adhesives [30] https://nobelusuniversity.com/2026/04/29/best-practices-for-laminate-and-film-storage — Nobelus University — Best Practices for Laminate and Film Storage [32] https://lloydsofindiana.com/heavy-toner-uv-coating — Lloyds of Indiana — UV Coating Adhesion Problems on Toner Prints [35] https://laminationservices.com — Lamination Services — published capabilities and trade price list (Salado TX)
Or call (254) 290-6337 and ask for Sam.