After making a set of placemats from a charm pack, and not prewashing, there was so much shrinkage, (over an inch!!!), that I will never again not prewash them. I now do a rinse in the sink, as paperprincess suggested. Roll them in a towel to get most of the moisure out, then press with a hot, dry iron. SOme did need a bit of squaring uo when I was done, but my quilt didn't shrink like thev placemeats did.
Patti