anytime you purchase (used)fabric- from a source outside of an actual store selling new fabrics-- the first thing you should do is WASH THEM! you never know what might be on the fabrics- from soils/oils/ perfumes---to bugs
whether it comes from an on line source or from a thrift store/yard sale- it should be washed before you do anything with it---for your safety and the safety of your family. lice, fleas, bed bugs, spiders....all kinds of critters can be in the fabrics- you have no idea if they've been in a box in a barn for years- or where they have been stored.