I overcast the edges on my last piece no problems

I have a front loader (grrrr...don't go there) which does have the nice feature of "rinse and spin." I don't get much ravel effect when I do large pieces. I figure the rinse and spin is enough to get the dust and extra dye out (using a Color Catcher for that) and then any shrinkage is taken care of with the dryer. Plus the whole thing will be completely washed when it's finished. Works for me!

You'll get dozens of dirfferent 'tricks and tips', most of which take quite a bit of extra time, put 'agitated' pin holes in your brand new fabric, waste thread and machine time, and/or don't work.

I pre-wash everything, mostly yardage from 3 to 6 yards but sometimes up to 10, and don't do anything special to it at all before it goes in the washer. I wash the unfolded fabric on the gentle cycle with plenty of water and only with other fabric, never with regular laundry. After washing, I trim any long 'thread trash' with the scissors that live on my dryer, shake any kinks out and toss it into the dryer. It comes out completely knot free, pretty much wrinkle free, and never ravels more than a scant quarter inch. :)

I've been washing tons of yardage this way for over 15 years and have NEVER had any of it wind up in knots in either the washer OR the dryer. People never believe it works, but that's their loss, not mine. :D

I serge both cut ends of the fabric. Magic--not loose threads and no lost yardage.
SandyQuilter

A small diagonal cut at each corner stops the raveling.

I washed about 12 yard piece of unbleached muslin in my front loader a few years ago and it came out just fine. I did not do one blessed thing but unfold and throw it in.

I use a rotary cutter wavy edge blade, works for me :)

I zig zag the cut edges to prevent raveling, but I also cut the corners off--just a small snippet. Then, if your fabric ravels, it will run just across the fabric once because you cut the corners. I would not cut the fabric any smaller; you will need the very piece you cut too small. Murphy's Law works well in fabric.

how about using a lingerie bag or putting the fabric in a pillow case?

I have used pinking edges (with my rotary cutter pinking blade) and it really helps