no I didn't prewash this fabric.....usually I do but was impatient to start. The iron is hot and I have held it there a long time.....in some places it sticks and in others it doesn't. I ended up pinning as much as I could to get it to stay in place. I only have enough of the fleece to do one bag so may try batting or something for the other one. I'm almost done with this one. Doing the handles now. Just frustrated with it.