Cold Foil Adhesive: UV Flexo vs UV Offset Selection Guide

Cold foil stamping is an in-line decoration process where a UV-curable adhesive is printed onto the substrate, the metallic foil is nipped against the wet adhesive, UV-cured, and the carrier PET is peeled away. The single biggest variable in a stable cold-foil line is the adhesive — and the choice between a UV flexo and a UV offset chemistry determines everything from line speed to defect rate.

This guide compares the two adhesive families at the spec level so you can spec the right SKU on the first order. For a deeper look at the full workflow, see our step-by-step cold foiling process guide and the broader hot vs cold vs digital foil comparison.

1. Why the adhesive is the bottleneck

The cold foil itself is a relatively passive component — a 12 µm PET carrier with a release coat, color lacquer, metallized aluminum, and a sizing layer. What actually bonds to the substrate is the printed UV adhesive. If the adhesive is wrong for the press, three things happen: pinholes appear in solids, fine type "tunnels" and loses edges, and foil waste climbs above 25%.

2. UV Flexo cold foil adhesive — high-definition, high-speed

UV Flexo Cold Foil Adhesive is metered through an anilox roll and printed via a photopolymer plate. Typical operating window:

• Viscosity at 25°C: 250–450 mPa·s
• Anilox BCM: 3.5–5.0 (typical 4.0 BCM at 800–1000 LPI)
• Coat weight on substrate: 1.8–2.6 g/m²
• UV cure dose: 80–120 mJ/cm² (Hg medium-pressure lamp)
• Line speed: up to 250 m/min on a narrow-web press
• Best for: labels, flexible packaging, fine type ≥4 pt, halftone foiling

The flexo route gives the cleanest fine detail because plate relief produces a sharp adhesive edge. It is the default for narrow-web label work on coated paper and BOPP, and it pairs especially well with our transparent BOPP self-adhesive film and gloss white self-adhesive label paper.

3. UV Offset cold foil adhesive — high-thixotropy, anti-misting

UV Offset Cold Foil Adhesive is split between the ink-train rollers and laid down through a litho plate. Different physics, different spec sheet:

• Viscosity (Laray) at 25°C: 30–55 Pa·s — much higher, paste-like
• Tack: 180–240 (Inkometer, 1200 rpm, 30°C, 1 min)
• Coat weight: 2.5–3.5 g/m² (heavier than flexo by design)
• UV cure dose: 100–150 mJ/cm²
• Line speed: up to 15,000 sheets/hour on a B1 press
• Best for: folding cartons, premium commercial print, large solids

The offset chemistry must be highly thixotropic — it has to flow under shear in the ink train but stay put on the plate to prevent misting at speed. This is why bargain offset cold foil adhesives fail above 12,000 sph: they mist, contaminate the foil web, and force a slowdown.

4. Spec-level decision matrix

5. Pairing the adhesive with the foil

Both adhesives are designed to bond with the sizing layer on standard cold stamping foil. For holographic or pattern-release jobs, switch to a higher-tack variant and use our holographic rainbow foil, which carries a slightly tackier size to compensate for the diffraction layer's lower surface energy.

6. Five real-world case studies

1. Wine label, 80 gsm gloss paper, 8 pt serif: UV flexo at 4.2 BCM, 2.1 g/m², 180 m/min. Foil waste 9%, zero pinholes.
2. Cosmetics carton, 300 gsm SBS, full-coverage gold panel: UV offset at 12,000 sph, 3.2 g/m², 130 mJ/cm². No misting after 4-hour run.
3. Pharma blister lidding, PET film: Flexo only — offset adhesive's higher coat weight cracked under blister forming.
4. Premium spirits carton, 350 gsm coated board, holographic registered foil: Offset adhesive + holographic foil, register tolerance ±0.15 mm.
5. Shrink sleeve, 50 µm PETG: Flexo adhesive with a low-shrink chemistry — offset's higher cure dose distorted the film.

7. Order checklist

When you request a quote, share these six values so we can ship the right SKU on the first PO:

• Press type and maximum running speed
• Substrate (grade + gsm or µm)
• Largest single foil element and finest type size
• Anilox BCM and LPI (flexo) or ink-train roller diameter (offset)
• UV lamp type and dose
• Annual foil consumption in m² or kg

Send your spec sheet through our cold foil adhesive enquiry form and our technical team will respond with a matched recommendation within 24 hours.