Cold foil stamping decorates a printed substrate by transferring a metallic layer onto UV-curable adhesive, inline with flexo or offset printing and without a heated die. This page explains how the transfer film is built, which press variables decide the result, and how a foil grade should be qualified before it goes into production.
The process runs as one continuous chain inside the press rather than as a separate finishing operation. Adhesive is printed in the artwork shape, the foil web contacts it at a controlled nip, UV energy cures the bond, and the carrier is rewound while the decorative layer remains only where adhesive was applied.
Because the image comes from a printed film of adhesive, the quality of that film governs everything downstream. An uneven, contaminated or under-cured adhesive layer changes how the foil releases, and the consequence appears on the sheet as missing metal, ragged edges or foil in unwanted areas. The press setup checklist covers the order in which those conditions are verified before a production run.
A flexo or offset unit prints a UV-curable adhesive in the exact shape of the artwork. Because the image is printed rather than tooled, plate changes replace die manufacturing, and the adhesive film itself becomes the first thing to control.
The metallised PET web meets the still-wet adhesive at a controlled nip while UV energy cures the bond. The carrier is then rewound and the decorative layer stays only where adhesive was applied, so nip loading and web tension decide edge quality.
Since curing happens inline, later units can print process or spot colour directly over the metallic surface. That is how tinted metallics and gradients are produced without a second pass, subject to ink and varnish compatibility.
Hover or tap any layer of the foil construction to inspect its thickness, function and material chemistry.
A cold foil is not a single material but a coated stack carried on a polyester film. Only part of that stack transfers to the substrate; the carrier stays behind on the press and is handled as a separate stream at the converting plant.
Understanding which layer does what makes press faults easier to read. Release problems point to the interface between carrier and metal, dull or mottled areas usually point to the adhesive and substrate, and colour deviation normally sits in the lacquer system rather than in the metallisation.
The dimensionally stable film that transports the decorative stack through the press. It is rewound at the converting plant and does not form part of the finished pack.
The layer that decides how readily the metal separates from the carrier. Release has to be matched to the adhesive system; a grade tuned for one adhesive can shed foil dust or leave voids with another.
A vacuum-deposited aluminium layer, optionally embossed with a diffraction pattern for holographic grades. It provides the reflectivity but contributes very little thickness.
Lacquers that create gold, copper, champagne or coloured metallic effects and anchor the metal to the adhesive. They also influence overprint receptivity.
Individual grades differ in release behaviour, lacquer chemistry and overprint receptivity. The cold foil product range lists the finishes we supply, and each one should still be confirmed against your own adhesive and substrate before it is specified.
Transfer quality is almost never decided by a single setting. It emerges from the interaction of the adhesive film, the nip, the foil web and the cure, and a change in one of them usually requires a compensating change elsewhere.
Use the following as the list of things to establish on a press trial. None of them should be treated as a fixed specification: press model, substrate, adhesive, lamp system, coverage and foil grade determine the final settings for each job.
Sealed, low-absorbency stocks hold a defined adhesive film. Uncoated or absorbent stocks draw adhesive into the sheet and dull the metallic effect unless primed.
Too little adhesive leaves incomplete transfer; too much causes squeeze-out, edge halo and contamination of the release layer. Anilox volume and viscosity are the usual levers.
Foil must contact adhesive evenly across the full width. Uneven nip loading is one of the most common causes of transfer that is clean on one side of the sheet and patchy on the other.
Slack web creates wrinkles and creases; excessive tension distorts fine detail and stresses splices. Tension normally needs re-checking as roll diameter changes.
Under-cure leaves tack and weak adhesion; over-cure can embrittle the bond and change overprint behaviour. Measure lamp output with a radiometer rather than assuming nominal values.
Release force determines whether fine detail breaks up or whole areas lift. It is a property of the pairing between foil and adhesive, not of the foil alone.
Temperature and humidity influence substrate behaviour and adhesive rheology, so a window established in one season may need adjustment in another.
Overprint inks, varnishes, lamination and any migration requirements should be part of the setup decision, not discovered after the run.
When a fault does appear, working backwards from the symptom is faster than re-setting the whole unit. The cold foil defects photo guide maps common visual symptoms to the variable most likely to be responsible.
These three elements form a single system. The substrate decides how much of the adhesive stays on the surface where it can hold foil; the adhesive decides how much energy is needed to cure it properly; and the cure decides whether the bond that results is durable and printable.
On a sealed coated board, most of the adhesive remains available at the surface, so a modest film weight gives clean transfer. On an absorbent or uncoated stock the same film weight can disappear into the sheet, which tempts operators to increase adhesive — and that in turn raises squeeze-out, edge halo and cure demand. The more productive correction is usually a primer or a substrate change rather than more adhesive.
Cure sits at the end of the chain and is easy to misjudge. Lamp output falls over lamp life, and a dose that was adequate at commissioning may not be adequate months later at higher speed. Under-cure typically shows as tack, poor tape-pull results and overprint problems; over-cure can produce a brittle bond and cracking on scoring or folding lines.
The three routes reach a similar visual goal by different means, and the choice is usually made per job rather than per plant. The table below compares how they behave structurally; it does not rank them, because the right answer depends on the artwork, the substrate and the run length.
| Characteristic | Cold foil | Hot stamping | Digital metallic |
|---|---|---|---|
| Image carrier | Printed adhesive image (plate) | Engraved metal die | Digital toner or polymer image |
| Heat applied to substrate | No | Yes | Varies by system |
| Tooling lead time | Plate making | Die engraving | None |
| Relief / emboss in the same station | No | Yes | Some systems add height |
| Overprintable inline | Yes | No | Depends on configuration |
| Heat-sensitive films | Yes | No | Depends on system |
| Typical run-length fit | Medium to long inline runs | Short to medium, or where relief is required | Short runs and variable data |
| Where cost sits | Consumables and foil economy | Tooling and makeready | Click or consumable cost per unit |
Many converters keep both foil routes available and select by brief. Where sculpted relief or very coarse uncoated stock is involved, hot stamping remains the stronger option; where inline throughput, heat-sensitive films or overprinted metallics matter, cold foil generally is.
Qualification means reproducing your own production conditions rather than accepting a datasheet. Run the candidate grade with the adhesive and lamp configuration you use, on the substrates you buy, at the speed you intend to sell.
A practical sequence is to begin with a short appearance and adhesion check at reduced speed, then step up to production speed while watching transfer edges and foil dust, then hold a longer run to see whether release behaviour drifts as the foil roll diameter changes. Finish with the downstream checks that matter for the job — overprint adhesion, varnish or lamination compatibility, tape pull, scuff resistance and any migration or compliance testing your market requires — and record the settings that produced an acceptable result so the job can be repeated.
If you would rather evaluate finishes before booking press time, the cold foil sample kit lets you review physical swatches against your artwork and substrate first.
The two dominant routes differ mainly in how adhesive is metered and how the web or sheet is handled. In narrow-web and wide-web flexo, adhesive volume is set by the anilox and the plate, which makes the anilox specification a central variable. In sheetfed offset, adhesive is delivered through a plate and blanket in a foil tower, so blanket condition and packing become the equivalent controls.
Both routes then converge on the same requirements: even nip contact, stable web tension, sufficient cure and a foil grade matched to the adhesive. Detailed, route-specific guidance is set out in our pages on flexo cold foil stamping and offset cold foil stamping.
Engineering and procurement questions we hear most often from converters and brand owners evaluating cold foil stamping.
Ask our technical teamThe fastest way to move from theory to a usable specification is a trial on your own press, with your substrate and adhesive. Send us the press model, substrate, artwork character and target run length and we will recommend the grades worth testing.