I'm building a library of color swatches using Dharma Trading's fiber reactive dyes. Each sample is created using only one dye color on a 100% cotton handkerchief. Fabric is pre-soaked in soda ash water. Then fabric is crumpled, placed in a cup, ice added, then dye sprinkled on top. In dye lingo, that's SOS (soda ash soak) and DOI (dye over ice). Development time ranged from 4 hours to overnight.