Guide

Why foil business cards need two separate files

Foil isn't printed with ink — it's a separate finishing step that presses a thin sheet of metallic film onto the paper with heat and pressure. That means regular (CMYK) printing and foil stamping run on completely different machines, in completely different processes. So the file a print shop needs is naturally split in two as well.

What goes on the base plate vs. the foil plate

The base plate holds everything except the foil — text, logo, background — in CMYK. The foil plate holds only the area that gets foil, filled solid black at 100%. Think of the foil plate less as color and more as a coordinate map that says “stamp foil here.” Both files share the same canvas and coordinates so they line up exactly when overlaid.

Why the foil file is the tricky one

Foil needs to stamp with a crisp, clean edge, so it can't use photos or gradients — it has to be vector (lines and shapes) only. Lines that are too thin won't hold the foil properly, so they need to stay at or above 0.2mm, and text needs to be at least 7.5pt or it comes out mushy. When an AI-generated image gets traced straight into vectors, it's common for some lines to end up thinner than that.

Resolution and file format need a separate check too

The base image needs to be at least 300 dpi so it doesn't look blurry when enlarged, and the file format print shops actually accept is usually PDF/X-1a. AI-generated images often fall short of that resolution, or simply aren't in a print-ready format to begin with.