Perhaps the most common type of t-shirt printing is screen printing; small businesses and individuals often use this method to produce shirts in small or custom batches. The cost of doing screen printing is relatively low, and very little special equipment is necessary for at-home jobs. Heat transfer and sublimation are two other methods. Sublimation is the most difficult, and it should generally only be done on synthetic materials such as acrylic. Heat transfer is an easy process that is quicker than screen printing, though the final product may not last as long.
Heat transfers are usually done on white t-shirts to avoid problems of conflicting colors, though the transfers can be put onto any color the printer desires. It is one of the quickest methods of printing, as a pre-made transfer design is simply heated and applied to the t-shirt. Heat transfers can be done at home using just a household iron and ironing board, though special equipment is available for large batches of shirts. While this is certainly a quick and easy option, it is hardly the longest lasting; transfers tend to crack after time, often leading to fading or other degradation of the image.
Screen printing is done with inks and mesh screens specially treated with a chemical that allows an image to be burned into it. A screen is coated with a substrate, which will harden when exposed to light. An image printed on a transparency can be placed on the screen, then the screen is exposed to light, causing the exposed substrate to harden while the substrate hidden by the transparency will remain soft. That soft substrate can then be washed away, producing an image on the screen. The screen is then placed on top of a t-shirt, and ink is pressed through the opening in the hardened substrate using a squeegee. The equipment investment is minimal, and screens can be washed and re-coated with substrate to burn a different image.
Sublimation is the quickest and long lasting of the t-shirt printing processes, though it is a limited process that can also be costly. It is generally only performed on synthetic materials such as nylon, and the investment of equipment will be more significant. The ink is heated in such a way that it turns to gas and is then transferred to the fabric. This process requires special inks, heating elements, and substrates that can significantly drive up the cost of a garment.
