Why is my cold foil peeling off after die-cutting?

Almost always under-cured UV adhesive or a substrate with surface energy below 38 dyne/cm. Measure cure energy with UV strips, corona-treat substrates to 42–46 dyne/cm, and verify tape-test adhesion within 30 min of print.

What causes whiskering around fine type?

Foil release tension is too low or the adhesive dot is oversized. Increase rewind tension 5–10%, reduce anilox BCM, and add a small choke on the adhesive plate so the film stays within artwork by 0.1–0.15 mm.

Can I overprint process colors on cold foil cleanly?

Yes — use UV inks with adhesion promoters, specify an overprint-friendly foil (silver PET with acrylic release), add 0.1 mm chokes in prepress, and chill the web after the foil station to prevent stretch-related misregistration.

How fast can I run cold foil?

Narrow-web flexo runs 150–250 m/min cleanly; sheetfed offset 12,000–15,000 sph. The ceiling is UV cure energy, not the foil itself. Every 10% speed increase needs a proportional lamp-power check.

How do I send a photo of my defect?

Upload the photo to Google Drive, Dropbox, or WeTransfer and paste the share link into the form. That keeps EXIF data intact so we can see substrate texture and defect scale accurately.

Press-side troubleshooting

Cold Foil Not Transferring Cleanly?

A substrate & UV adhesive checklist for converters, printers, and packaging engineers.

Quick answer

Most cold foil defects trace back to four variables: substrate surface energy, UV adhesive coat weight and cure, foil release tension, and press speed vs. lamp intensity. Diagnose one at a time — swap the foil last. Below is the same checklist our technical team uses on press-side calls.

Send us your defect UV adhesive deep-dive

Step 1 — Confirm the substrate is press-ready

Corona-treat coated board, BOPP, PET, and metallized film to ≥ 42 dyne/cm — verify with dyne pens each shift.
Run substrate within 24 h of corona treatment; treatment decays 2–3 dyne/cm per day on film.
Wipe silicone-release or waxy substrates with IPA on trial sheets to isolate contamination.
Keep humidity in the pressroom between 45–55% to avoid static and paper curl.

Step 2 — Dial in the UV adhesive

Target coat weight 1.2–2.0 g/m² for board, 0.8–1.2 g/m² for film — measure with a wet-film gauge.
Cure to 120–180 mJ/cm² UVA measured with an EIT Power Puck or equivalent strip. Under-cure is the #1 cause of adhesion failure.
Match adhesive chemistry to overprint requirements: choose overprint-compatible grades when process inks trap on top of foil.
Replace UV lamps at ~800 running hours or when intensity drops > 20%.

Step 3 — Balance foil release and press speed

Cold foil is speed-forgiving up to 250 m/min on narrow-web and 15,000 sph on sheetfed — but lamp power must scale with speed.
Rewind tension controls edge cleanliness. Too loose = whiskering; too tight = tearing on thin foils.
Store foil vertically at 18–24°C / 45–55% RH. Foil that has been shipped in a cold container needs 12 h to acclimate.

Step 4 — Swap the foil last

Because foil is the visible variable, teams often blame it first. In our data, less than 15% of press-side troubleshooting calls end with a foil swap — the rest are corona, cure, or coat weight. Send us your form below and we will identify the two or three most likely causes before you buy another roll.

Cause & fix matrix

Adhesion failure (foil rubs off, tape-test failure)

Likely cause	Press-side fix
Substrate surface energy < 38 dyne/cm (BOPP, PET, coated board with silicone)	Corona-treat inline to 42–46 dyne/cm; verify with dyne pens each shift.
UV adhesive under-cured — lamps aged or speed too high	Measure with UV strips (EIT Power Puck); target 120–180 mJ/cm² at UVA; lower speed or replace lamps > 800 hrs.
Adhesive coat weight too low (< 1.2 g/m²)	Increase anilox volume (BCM 3.5–5.0 typical) or switch to higher-viscosity grade.
Contaminated substrate (anti-set-off powder, plasticizer bloom)	Reduce powder, run within 24 h of printing, or wipe with IPA on trials.

Whiskering, stringing, hairlines around type

Likely cause	Press-side fix
Foil release tension too low — foil peels beyond adhesive edge	Increase rewind tension 5–10%; check dancer arm calibration.
Adhesive tacky at edges (over-application)	Reduce anilox BCM or add small dot-gain compensation in the plate; keep adhesive within artwork by 0.1–0.15 mm.
Static charge pulling foil fibers	Install ionizer bar before nip; ground the foil unwind.

Voids, pinholes, skipping in solids

Likely cause	Press-side fix
Air entrapment at the nip	Increase nip pressure gradually (start +0.05 mm); check impression roller shore hardness (65–75 Shore A typical).
Adhesive skinning between stations	Verify inter-station chill, reduce dwell, or switch to lower-reactivity monomer grade.
Foil not seated flat — telescoping roll	Reject rolls > 2 mm end-play; store foil at 18–24°C / 45–55% RH.

Dirty edges, halo, squash-out

Likely cause	Press-side fix
Plate wear or excessive impression	Reduce impression to kiss; inspect plate for embossed shoulders every 20k impressions.
Adhesive viscosity too low	Cool ink duct to 22–25°C; select higher-viscosity UV adhesive.
Anilox worn or plugged	Ultrasonic-clean anilox weekly; replace when volume drops > 15%.

Misregistration with process colors overprinting foil

Likely cause	Press-side fix
Substrate stretch after foil chill	Add chill roller after foil station; allow 30 s stabilization before wet trap.
Trap not compensated in prepress	Add 0.1 mm chokes on inks over foil; discuss with your prepress team.
Foil surface repels overprint ink	Use UV inks with adhesion promoter, or specify overprint-friendly foil (ask CFS for a spec sheet).

Send us your defect — free technical review

Fill in what you know. Our technical team replies within one business day with the two or three most likely causes and a specific fix to try on your next run.

Frequently asked questions

Sources & references

FTA — UV curing measurement best practices — Flexographic Technical Association
TAPPI T-402 — Substrate conditioning — TAPPI Standards
Reddit r/Printing — Cold foil adhesion threads — r/Printing community discussions

Last updated: 2026-07-13 · Author: CFS technical team