I used a stack of 10 inch squares layer cake that were good quality Woolies flannel, and I had Woolies yardage for sashing, setting and backing. I decided not to prewash because I could not do so to the layer cake, but on the advice of several online videos and articles I did use spray starch to stabilize the precuts. I was shocked to watch the flannel squares shrink before my eyes when the starch hit them (even before ironing) and many lost up to a half inch on a side or were no longer square. I had to revise my entire pattern measurements because I could no longer use the entire square as I'd intended. Unless I'm using precuts, I will always wash and dry flannel, no matter what the quality.