I use either Pellon Shapeflex (a fusible knit tricot) or Pellon 911Ff on tshirt quilts. I use steam or a damp pressing cloth to help with the adhesion, but find that if a t-shirt is a poly blend instead of 100% cotton, the fusible doesn't want to stick well--it actually needs a lower temp, which doesn't always work with all fusibles. Part of the reason I prefer the shapeflex.