Since my flannel quilts are utility: rag quilts, or pet quiltlets, or couch throws, I don't prewash. I prefer the 'rustic' look.

But, that's just me.

depends on the brand I washed connecting threads flannel and had barely any shrinkage so for that brand washing was a waste of time to me

I never wash any of my fabrics, and when buying flannels, I always get good quality flannel from my LQS. I've never had a problem...ever. I'm obviously in the minority. I just made a quilt with cottons on the front and Moda flannel on the back and it came out beautifully. Maybe I've just been lucky.

I made a queen size flannel quilt. I used what they called Quilters Flannel, I did not wash it first, and have had no problems, it has been washed a couple of times since I gave it to my daughter. I never pre-wash either, but if I did, I would wash in the same temperature of water as I would after it was made.

I pre wash mine, because it does shrink so much.

I don't prewash any fabric including flannel, I've done many flannel quilts, no issues here. Laundry is not my favorite I have four kids at home still. I wash once the quilt is completed

If you are using all new flannel and it is the same kind/weight, you can probably get away with not washing it. If you are mixing it with some that has already been washed you will need to wash it as it will not shrink evenly. Personally, I always wash flannel because some of it shrinks more than others and I don't want to ruin all my work by having it shrink unevenly. I do not usually wash cottons unless I suspect it might bleed.

I wash flannels twice and dry them in the dryer because they shrink all they will ever shrink. Another plus is that they get softer and cozier because the threads contract which increases the yarn fluff.

I've made lots of flannel quilts and always wash and dry. now you're gong to hate this but, I also use a 1/2 inch seam!
I find flannel quilts get lots of use and when I first started making them the seams were always fraying away to that's my story and I'm sticking to it ! Love the flannels.

http://www.quiltingboard.com/picture...o-t219761.html

I couldn't find the picture, but here is the thread. Anyway, I have since washed and dried all flannel. This was my first quilt, fabric from quilt store, I didn't know about prewashing options and teacher didn't say anything about washing. They are three inch squares, 1/4" seam, warm and natural batting. Still going strong. I may have to rethink washing flannel now.