iDye Poly is for synthetic fibers such as polyester and nylon. It will color almost anything synthetic, including plastics and acrylics, buttons, Frisbee discs, 3D printed objects, toys, dolls, wigs, urethane coatings and more! The dye comes in a dis-solvable packet, so there are never any messy powders to handle: simply drop the packet in a pot of water, add your fabric or objects and bring to a boil! Using iDye with Fabric Blends For blended fabrics that contain both synthetic and natural fibers, use iDye for Natural Fabrics with the corresponding iDye Poly color, AT THE SAME TIME! Or try pairing two different colors for more interesting two-tone heather effects. iDye Poly may also be used for sublimation transfer techniques and to dye the polyester threads that are used to sew many commercially manufactured garments.