Our fabrics are either:

They all dye well. Technically, non-optic whitened fabric dyes better (however, we find it hard to see the difference). For processes like tie-dye and batik, some folks prefer optically whitened, or at least well bleached, fabric so it is as white as possible in areas with no dye.

All of the fabrics that we offer are intended to be without treatments or finishes and are ready to dye as is. However, pre-washing or scouring is ALWAYS recommended! It gets out unseen oils from our hands and dirt and other oils that may cause blotchiness in dyeing. Fabrics get handled a lot and run through machines and everything else. They are not clean. Use Synthrapol or our Professional Textile Detergent and HOT water for pre-washing, and add some Soda Ash (1 cup/washing machine load) to that mix to really scour cottons and other plant fiber fabrics (but not wools or silks), especially natural ones that haven't been bleached.