The first time I bought batting (80%/20% low-loft cotton batting) at my local quilt shop, I asked if I should pre-wash it. The quilt-shop lady asked,

"Do you pre-wash your fabric?"

I answered, "Yes, I do."

"Then you should also pre-wash your batting."

So that's what I do.

I like the fact that with pre-washing, once it's quilted, and I've had it bunched up in my lap while sewing on the binding, that a "brand new" is already all soft and 'drapey' and cosy-looking when I gift it - but I mostly do lap and throw-sized quilts. I can see wanting a flatter result if you're making bed quilts.

Jan

No I do not wash batting. I prewash all fabrics, then, after the binding is done, wash the quilt. I use the Warm and Natural batting. It shrinks a little in the dryer the 1st time you wash it so it gives the quilt a really nice effect if you wash it after the quilt is finished.

I prewash warm and natural or warm and white to reduce the shrinkage. It still shrinks some the first I wash the quilt. Which I like. I haven't try warm and natural or warm and white in a quilt without prewashing it. So, I don't know what the difference would be in shrinkage pre or post washing in as a quilt.

I use poly batting. I don't prewash but sometimes I put it in a cool dryer to take out the wrinkles and fluff it.