This 1 pound bag of Soda Ash by Jacquard is a mild alkali that promotes the chemical reaction between Procion MX fiber reactive dye and cellulose fiber. Also known as sodium carbonate or washing soda, Soda Ash is necessary to activate and set Procion MX dye. For tie dye, use one cup per gallon of warm water. Soak fabric for 20 minutes, then wring out excess solution by hand. Do not rinse out. Made in the USA.