I always pre-wash my fabrics before quilting, except precuts like charm squares. This is especially important for colours like red, blue and black. I can't take the risk of them bleeding onto the surrounding colours after spending months on a beautiful quilt. To prevent fraying, I do a small triangular cut on each corner. This works for me.

sometimes i do, most times I don't. I wash the blues and reds and darks, etc. Shout color catchers are AWESOME!

If I was going to pre-wash my fabric I would do so before cutting the pieces to size and would also press before cutting.

I always pre-wash and all my fabrics no matter how small. My reasons, 1.If it is going to shrink it will before I use it, when I piece and quilt it, there won't be the tension on the threads pulling my stitching apart that would be if it isn't prewashed and shrinks in the finished project. 2. when I prewash I toss in the shout color catcher, and whatever dyes are released they won't be ruining my finished project.
I wash fabrics before putting them in with my stash. Sometimes with towels, or sheets, other times with regular laundry, and sometimes if I have a lot to wash I'll do a load of just the fabrics. I often will use a 2nd rinse too.

If I am spending my time to make a quilt or wall hanging I'd prefer to give it a fair chance to last as long as possible.

I just had a big mess with Hand dies bleeding all over my reindeer fabrics. I did not make the hand dies I bought them. I washed all the red fabrics together and the hand dies turned my reindeer fabric pepto pink. I even used Retayne in the wash cycle. I will from now on always wash hand dyes and batiks before using them. :)

Almost always--exception precut charm squares. I want to minimize surprises. Enough little issues crop up anyway!

My Mom had bought a collection of 5 inch squares. Either from Keepsake Quilting or Connecting Threads -

Most of them washed up nicely - there was one piece that shrank to 4.5 inches. That's at least 10% shrinkage.

Which is why I usually avoid buying precuts.

I prewash too for the same basic obvious reasons stated. But it's also a relaxing kind of thing for me too. Since I buy my fabs with no real project in mind, washing, ironing, folding, organizing it, etc., lets me enjoy the pieces that much more and allows me more time to think about what I could potentially make with it.

Guess it's my private bonding time with my new additions. :lol:

I agree on prewashing flannels because they always shrink, and my experience is that most muslins will shrink as well. so while I don't normally pre-wash, I do on both flannels and muslins (unless it says "pre-shrunk" on the bolt!

I always prewash...Yesterday I had a bunch of 5" charms to wash..when I fished them all helter skelter out of the washing machine, I decided to put them in a net bag before puting them in the dryer...Well that didn't work,they were all over the place again, but my Mom and I had a lot of fun stacking them up again...