TL;DR. Cold foil on folding cartons is a sheetfed-offset job, not a label job. It lives or dies on three numbers: a C1S or SBS board with a smooth coated face (PPS roughness < 1.5 µm), a UV adhesive coat weight of 1.1–1.4 g/m² laid down by an anilox unit feeding the first printing tower, and a register tolerance under ±0.10 mm so the CMYK overprint lands cleanly on the metallised area. Get those right and you are looking at 12,000–15,000 sheets per hour with a foil yield above 92 %. Get them wrong and you burn foil, miss the brand-approval gloss target, and end up paying hot-stamp prices for a cold-stamp job.
“"Cold foil now accounts for roughly one third of all metallic decoration on European folding cartons, up from 18 % in 2019, driven mainly by inline sheetfed UV presses installed since 2021." — Pira / Smithers, The Future of Metallic Effects in Packaging to 2027
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1. Why folding-carton converters moved to cold foil
For thirty years, the default way to put a silver area on a folding carton was hot stamping — a separate offline pass on a Bobst Foilmaster or similar, with a heated brass die for each design. It works, but it is slow (3,000–4,000 sheets/hour), it needs a die per SKU, and it locks the brand into long runs to amortise tooling.
Cold foil changed three things at once:
- Inline with offset. The foil station sits inside the same Heidelberg, KBA, Komori or manroland press that lays the CMYK, between the first and second printing units. No second pass, no second handling, no second WIP buffer.
- No die, no plate change cost. The image is defined by a thin printing plate carrying the UV adhesive. New SKU = new plate, the same way you would change a black plate.
- Overprintable. Because the foil is laid before CMYK, the inks print over the metallised area, creating coloured-metallic effects (rose-gold, ruby-red, emerald-green) that hot foil simply cannot produce without a second pass and a custom-coloured foil roll.
The first two points cut total cost per SKU on short and medium runs (5,000–80,000 sheets). The third point is what brand owners actually pay for — see our breakdown in CMYK over cold foil: building the rainbow metallic effect.
2. Board: what cold foil will and will not mirror
Folding-carton board is not one material. The four families a carton converter quotes from each behave differently under cold foil adhesive:
| Board family | Typical grammage | Surface (PPS µm) | Cold-foil result |
|---|---|---|---|
| SBS / GZ (solid bleached sulphate) | 230–400 g/m² | 1.0–1.5 | Mirror finish, 90+ GU at 60° |
| FBB / GC1–GC2 (folding boxboard) | 230–350 g/m² | 1.2–1.8 | Mirror on top coat, slight satin on reverse |
| WLC / GD2 (white-lined chipboard, recycled) | 250–400 g/m² | 2.0–3.5 | Satin only, expect 65–80 GU |
| Microflute E/F (litho-lam) | 250–350 g/m² liner | 1.5–2.5 | Possible, but watch for flute show-through on solids |
The PPS (Parker Print Surf) roughness number is the one to ask the board mill for — not Bekk, not Bendtsen. Anything below 1.5 µm gives a true mirror at standard 1.2 g/m² adhesive coat weight. Above 2.5 µm and you should be quoting the brand owner a "metallic satin" finish, not a mirror, no matter what the foil supplier promises.
For recycled WLC, talk to the converter about a white pigmented topcoat before the foil station — it lifts a typical GD2 from 65 GU to about 82 GU, at a paste cost of roughly €0.02/m². Cheap insurance.
3. Adhesive: the only number that really matters on press
Cold-foil adhesive on a folding-carton press is UV-curable acrylate, applied through a chambered doctor blade onto an anilox roller, transferred to a flexible photopolymer plate, and printed onto the board in the same way you would print a varnish. The single most important press-side number is coat weight:
- Smooth SBS / FBB: 1.1–1.3 g/m²
- Recycled WLC / lightly textured stock: 1.4–1.6 g/m²
- Above 1.7 g/m²: adhesive squeeze-out, foil contamination, blanket pickup
Coat weight is set by the anilox cell volume. The working window for folding cartons is 8–14 cm³/m² with a 60° hexagonal screen at 200–250 lpi. Going coarser fills pinholes on rough board but blurs fine type; going finer holds detail but starves the solids. For a deeper press-side walkthrough see our anilox roller selection guide.
The adhesive must be fully cured before the nip, which means a UV lamp (mercury arc or LED-UV at 395 nm) immediately after the foil station, delivering 120–180 mJ/cm². Under-cured adhesive will lift off in the delivery pile and contaminate the next sheet.
4. Register, overprint and the rainbow effect
The reason a folding-carton brand manager chooses cold foil over hot foil is almost always overprintable colour. The press lays:
- 1Adhesive (image area)
- 2Foil web nip + UV cure + foil rewind
- 3CMYK in the four following towers
- 4Inline UV varnish or aqueous coating
Because steps 2 and 3 happen on the same sheet path with no re-registration, the CMYK lands on the metallised area with the same tolerance as any other process colour — ±0.10 mm or better on a modern XL 106. That is what makes ruby-red, rose-gold and holographic-effect cartons possible without buying a roll of every colour.
Prepress for the designer is non-trivial. Cold foil needs its own spot channel, trapping rules differ from CMYK, and the ink density curve over a metallic substrate is not the same as over white board. The full workflow is in our cold foil prepress designer guide. Send that link to the brand-side designer before the first proof, not after.
5. Embossing, debossing and tactile finishes over cold foil
A common question from premium-carton buyers: "Can we emboss the foil area?" Short answer: yes, and it is one of the strongest visual upgrades you can add for almost no extra cost per sheet.
The sequence matters:
- Print cold foil + CMYK inline on the offset press.
- Apply UV spot varnish (gloss or matt) over the foil if a tactile contrast is required.
- Offline emboss / deboss in a separate pass on a flatbed (Bobst Mastercut, Heidelberg Easymatrix) using a brass or magnesium die.
Cold-foil aluminium is soft enough to take a 0.4–0.8 mm emboss depth without cracking, as long as the board itself can carry the deformation. SBS at 300 g/m² is the safest substrate. Avoid embossing over WLC under 280 g/m² — the recycled fibres crack at the foil edge.
For carton designers comparing finishes head-to-head, the hot vs cold foil stamping buyer's guide lays out where each method still wins.
6. Recyclability and the 2026 packaging regulation question
The single most common procurement question we get from European folding-carton buyers since the EU Packaging and Packaging Waste Regulation (PPWR) came into force in 2025 is: "Is this carton still recyclable in the standard paper stream after we add cold foil?"
The short answer is yes, within limits. Cold foil deposits an aluminium layer of roughly 20–50 nanometres — about 1,000 times thinner than household foil. Industry repulping trials (CEPI, ATIP, the German PTS Institute) consistently show that cold-foil-decorated SBS and FBB cartons pass standard ISO 5269-1 repulping with no disposal-stream change at foil coverage up to about 20 % of the carton face area.
The numbers to keep in the spec:
- Foil coverage ≤ 20 % of decorated face: recyclable in standard paper stream, no flag.
- 20–40 % coverage: still recyclable, but disclose to the brand owner for PPWR Article 6 compliance.
- > 40 % coverage: treat as a metallised carton, route to specialised recovery.
Full data and citations in our is cold foil recyclable? explainer, and a mono-material strategy for very high foil coverage in cold foil for mono-material recyclable packaging.
7. Cost: what folding-carton cold foil actually runs in 2026
The cost question always sounds simple and never is. Here is the working model carton estimators use for European converters in mid-2026, on a Heidelberg XL 106 or KBA Rapida 106 with an inline cold-foil unit:
| Cost component | Typical value (EUR per 1,000 sheets, 70×100 cm) |
|---|---|
| Cold-foil consumable (foil roll, ~5 % yield loss) | 28–42 |
| UV adhesive | 6–9 |
| Press time premium vs plain offset | 12–18 |
| Plate (foil image plate, amortised over 30,000 sheets) | 3–5 |
| Total cold-foil cost / 1,000 sheets | 49–74 |
Compare to a hot-stamping pass on the same image area: €95–140 / 1,000 sheets for runs under 30,000, mostly driven by die cost and the slower second-pass press time. Cold foil breaks even with hot foil at roughly 8,000–12,000 sheets for a single SKU and wins outright above that.
For a full calculator that lets you plug in your own image area, foil width and run length, see the cold foil stamping cost calculator.
8. Troubleshooting: the four defects that cost folding-carton runs
After fifteen years quoting carton cold-foil jobs the same four problems account for about 80 % of all reprints:
- 1Pinholing on solids. Almost always under-coated adhesive on rough WLC, or a starved anilox. Step coat weight up by 0.2 g/m² before changing anything else.
- 2Ragged foil edges on fine type. Plate hardness too low for the detail, or adhesive flowing outside the image. Move to a 70 Shore A plate and check tape build under the plate.
- 3Dull, grey "metallic". Under-cured adhesive, or board PPS above 2.5 µm. Verify UV lamp output with a strip; if cure is fine, the brand has to accept satin not mirror.
- 4CMYK loses density over foil. Ink film starves on the slick metallic surface. Increase CMYK ink density curve by 5–8 % over foil area, or print a thin white underprint between foil and process colours.
A full diagnostic flowchart for pinholes and ghosting is in cold foil pinholing & ghosting: diagnosis flowchart, and the machine-side checks live in cold foil stamping machine: how it works, cost, speed and buyer spec guide.
9. Working spec sheet for a folding-carton cold-foil job
Use this as the brief when you send a job out to quote. If a converter cannot answer all of it, the quote will not hold:
- Board grade and grammage (SBS 300, FBB 290, WLC 350, etc.)
- PPS surface roughness target
- Foil coverage % of carton face area
- Number of SKUs and run length per SKU
- Required gloss (GU at 60°) and whether mirror or satin is acceptable
- Overprint colours required on the foil (CMYK only, or spot inks)
- Emboss / deboss over foil yes / no, depth, registration tolerance
- Recyclability claim required (FSC, PPWR Article 6, How2Recycle)
- Brand-approval sample timing — usually 10–15 working days from artwork sign-off
Cold foil on folding cartons is a mature, well-understood process in 2026. It rewards specification discipline and punishes wishful thinking. Tighten the brief, hold the press numbers, and the cartons will sell themselves on the shelf.
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FAQ
Is cold foil on folding cartons cheaper than hot foil? On runs above roughly 8,000–12,000 sheets per SKU, yes — by 30–50 % per 1,000 sheets, mostly because there is no die cost and no second-pass press time. Below that break-even, hot foil can still be competitive.
Can I print CMYK over cold foil on a folding carton? Yes — this is the main reason carton converters chose cold foil over hot foil. The CMYK lands inline on the same sheet, with the same ±0.10 mm register as any other process colour, allowing rose-gold, ruby-red, emerald-green and holographic effects from one foil roll.
Will a cold-foil folding carton still be recyclable? At foil coverage up to about 20 % of the carton face area, industry repulping trials show no impact on the standard paper recycling stream. Above 40 % coverage, treat the carton as metallised packaging.
What gloss level can I expect on recycled (WLC / GD2) carton board? 65–80 gloss units at 60° as standard; 78–85 GU with a white pigmented topcoat before the foil station. True mirror finish (≥ 90 GU) generally needs SBS or FBB board with PPS roughness below 1.5 µm.
Can I emboss or deboss over a cold-foil area on a carton? Yes — cold-foil aluminium is soft enough to take 0.4–0.8 mm emboss depth without cracking. Do the emboss offline after the inline foil + offset pass. Avoid embossing on recycled board under 280 g/m².
How long does a cold-foil sample carton take to produce? A genuine production-press sample on the brand's specified board takes 10–15 working days from approved artwork. Digital mockups are faster but do not predict gloss, register or overprint colour accurately enough for brand approval.