I bought 2 1/2" strips from Keepsake Quilting. Should I prewash these before sewing them onto a sweatshirt that will soon be a jacket. I will be totally covering the sweatshirt with fabric.
The strips are all shades of blue batiks from very dark to very light.

is the sweatshirt 100% cotton? I don't pre-wash most things, would never pre=wash a strip for fear of losing most of it to strings and distortion. But I would sew the unwashed strips onto the unwashed shirt and let them shrink together. That's what I did on a sweatshirt I made into a jacket.

I already washed the 100% cotton sweatshirt. Oops!

You sound like me.

Sibyl

I guess I'm more concerned about the colors bleeding than shrinkage. Should I be worried about shrinkage? I think I will just give her a couple of color catchers when I give my mil the jacket.

I wouldn't. They will probably fray.

I wouldn't wash them..too much fraying. I made a similar jacket using various shades of blue batiks and I can't stop looking at it because the colors are so pretty. Your MIL will love hers!

I never wash pre-cuts. It makes a mess.

I agree with the others...too much fraying...

I wouldn't try to wash them, could end up a tangles mess and hard to sew

Sounds pretty!

Since sweatshirts often shrink much more dramatically than woven cottons, I'd pre-wash the sweatshirt.

For the strips, I'd just lay them out on my drying rack, use a mister bottle full of hot water to thoroughly dampen them and then let them air dry. That should let them do any shrinking they're going to do without risking any fraying.

With batiks, most of the shrinkage that happens is due to the machinery that folds the yardage, then winds them onto the bolts. It only takes some dampening to let the fabric relax back to its original size.

The manufacturers don't recommend washing the strips.

Do you have a picture of your jacket? I would love to see it!