With Metallic Accent products, a.k.a WonderFoil, you can turn a wide range of CMYK colors, into multi-colored foils. When doing a metallic postcard, sticker, business card, etc, a foil mask must be created and uploaded with your full color CMYK file. The file for the "metallic" mask MUST ONLY be black and white (100% Black). 100% Black in the areas you want the foil, and white (0%) in the areas you do not want the foil. Click for more info.