In terms of how long an iron-on heat transfer paper design will last on a T-shirt, the answer can vary. Typically, a well-adhered iron-on transfer image using high-quality paper should last a few years before it starts to fade, crack or peel from your substrate (e.g., a cotton T-shirt). An important note: Iron-on transfer images adhere on top of your garment, material, or T-shirt (hence why it’s important to cut cleanly around the edges for the most polished, professional look). Since the images are technically on top of your garment when transferred, they are not fully integrated with the fabric. Therefore, images transferred via heat transfer paper are never fully permanent and eventually tend to peel or crack. (Sidenote: Sublimation, a process whereby special inks are literally infused into the substrate, is a permanent and totally crack-resistant, peel-resistant method of image transfer. However, it's more involved and costly).