I'm with you.... hate to throw away usable fabric. But, I think I'd wash everything before cutting it up just to see how machine washing will affect it. I would be very unhappy if I spent a ton of time putting together a quilt and then discovered that it shrank badly or faded all over the other blocks (although polyester usually doesn't bleed color). Just sayin'..... be cautious. Drapery material my not respond the same as 100% cotton.