Soda ash (sodium carbonate) dye fixative is a mild alkali that promotes the chemical reaction between the reactive dyes in Procion MX fibers and the cellulose fiber. Also known as "washing soda," "salt soda," or "soda ash," sodium carbonate is necessary to activate and fix the Procion MX dye.

For tie-dyeing (pre-soaking):

Use 0.23 kg (1 cup) per 3.79 L (1 gal) of warm water. Soak the fabric in the mixture for 20 minutes. Squeeze out excess solution by hand. Do not rinse.

For immersion dyeing cellulose fibers:

Use 57 to 78 g (1/4 to 1/3 cup) per 11.36 L (3 gal) of water. Add to the dye bath according to instructions.

For washing machine dyeing cellulose fibers:

Use 0.47 to 0.71 kg (2 to 3 cups) per load. Dissolve in 0.95 L (1 quart) of warm water. Gradually add to the washing machine dye bath according to instructions.