What is cold foil?

The mechanism is straightforward: an adhesive is printed exactly where the foil should go, the foil ribbon is pressed against the sheet, and it sticks only to the adhesive. Because the adhesive comes from a printing plate, the resolution is plate resolution — which is why cold foil holds fine detail, small type and complex shapes that hot stamping would struggle with.

The two big commercial differences from hot foil are tooling and speed. There is no engraved die, so there is no per-design tooling cost, and it runs at press speed inline rather than as a separate pass. On a long run those two facts make it substantially cheaper. On a short run, hot foil’s tooling cost is spread over fewer units but the overall picture usually still favours hot foil for small quantities.

It also opens a possibility hot foil does not: because the foil is a printable silver base, process colours can be overprinted onto it to create metallic colours — a metallic red, a metallic blue — from a single silver foil. That is a genuinely different design tool rather than a cost saving.

What it gives up is a little brilliance and the slight relief that hot stamping’s pressure creates. For a large decorative area or fine metallic detail, cold foil is usually right; for a small, sharp, maximally reflective logo, hot foil still wins.