Sublimation is the process of changing from a solid to a gas without passing through an intermediate liquid phase. The dye sublimation process uses a heat sensitive sublimation dye, dissolved in a liquid, to print images onto a special transfer paper. Once printed onto paper, the liquid dries into a solid. The dye sub transfer and the garment that the image is to be applied to are then placed into a heat press for a specific time. When the heating cycle is completed, the image on the paper has been transferred onto the garment and has actually become a part of the fabric. Done correctly, it cannot be washed out or come off, unless the actual fibers are damaged. Colors remain bright, wash after wash and will not run outside of the image area. Although dye sublimation is still considered a heat transfer process, the fact that the dye permeates the material fibers is what makes it completely different from the traditional heat transfer method. With traditional methods, an image is printed onto a transfer paper and “adhered” to the surface of the material. That is why, after time, traditional heat transfers crack and peel off.
One of the challenges of dye sublimation is that it can only be done on synthetic materials. At high temperatures (400 degrees), the solid dyes in the print convert into a gas without ever becoming a liquid. The high temperature also opens the pores of the material and allows the gas to enter. When the item is removed from the heat, the temperature drops, the pores close and the gas reverts to a solid state. It has now become a part of the material. This is why dye sublimation can't be done on natural materials, like 100% cotton. Natural fibers and non-coated materials have no "pores" to open and so the dye just sits on top of the fabric.
The shirts we print on are made by Vapor, a company that specializes in producing garments for the dye-sublimation process. They have developed a material that is 100% polyester, yet feels like a very soft cotton. However, being polyester, the shirt is practically wrinkle-free and resistant to wear and tear.