I learned the hard way to pre-wash my fabrics. I tried to avoid it because I always ended up with a tangled mess of threads and fabric. Now before washing, I trim just a small bit of fabric away from all the edges using my rotary cutter with a pinking blade. And voila – no more tangled threads after washing! My mother taught me this trick only she used her pinking shears which often led to sore hands.
I use an Olfa cutter but most manufacturers have their own version. I only use the blade when pre-washing fabrics so it stays sharp for a long time. I’ve been using the same blade for over a year now.
Oh – I always use a color catcher in the wash!