All projects requiring special effects, such as Metallic Foil, will additionally require files called Black Mask files. A Black Mask file is where you indicate in 100% black (K) where the effect is to be placed on your printed pieces. We strongly recommend that all Black Mask files are created in a vector-based program (ex: Illustrator). Please also keep in mind that if you are intending your effect to be in alignment with your print shifts of up to 1/16" can occur. This is due to the fact that special effects are applied on separate machines from the regular printing machines. For more information please visit this link.https://www.4over4.com/metallic-wonderfoil-lenticular