Soda Ash, also known as sodium carbonate, washing soda, or sal soda, is a mild alkali that promotes the chemical reaction between Procion MX  reactive dye and cellulose fiber. Soda Ash is necessary to activate and "set" Procion dye. 

Available in three sizes:

• 1 lb. bag: $8.98
•  5 lb. bag: $18.98
•  25 lb. bag: $42.98