To care for T-shirts with an iron-on transfer design, wash them sparingly or as needed to prevent cracking, peeling or fading. When you wash them, turn them inside-out so the design isn't visible, and place them in the washer on a gentle or delicate and cold water cycle. Don't use detergent the first few times the T-shirt is washed. Lay the shirts flat to dry, or hang-dry them.
If possible, wash any iron-on transfer T-shirts alone or in a small load of delicates or light garments. Avoid washing them with heavy knits or jeans or any bedding or towels so the rougher fabrics don't run against the design. Avoid dark materials, as certain colors alter the coloring of some transfers. Don't put any item with an iron-on transfer in the dryer, even on a low setting, as any heat lifts the transfer or causes cracking.
Before placing an iron-on transfer onto a T-shirt, wash it by hand in cold water, and allow it to dry. Place the design on the shirt, and iron it on, following the directions that come with the transfer. Allow the transfer to completely cool before washing it by itself on a delicate and cold cycle. This helps to set the transfer and make it more resilient to future handling.