As a longarm quilter, please be kind to your longarm quilter by using a tricot iron-on interfacing to stablize the t-shirts. It is the only one that stays stuck down, doesn't add as much weight as other types and brands of iron-on interfacing, and it is soft. I find it helpful to use a thin pressing cloth (I use a plain "floursack tea towel) between your interfacing and the iron. The pressing cloth prevents any residue from the interfacing building up on your iron.