I pre-washed FQ's one time....never again!!
I'll use an entire box of color catchers before I deal with all those knots and strings again! I swear by the color catchers, though!! I bought a red, white and blue quilt at an auction, it had never been washed....I used 3 CC sheets and the red didnt bleed into the white!! The sheets came out blood red when the wash cycle was over.

I did read a tip the other day, not sure where, that said if you clip the corners off fabric, it cuts down on the amount of unravelling...I havent tried it so I cant vouch for the tip.