Scouring fabric is one of the very first steps in natural dyeing. It fully cleanses the fabric, preparing it to properly accept the dye. Without it, colors may not be light-fast and can appear uneven. This scouring kit is for cellulose fibers (cotton, hemp, linen) and contains 4 oz. of scour and 2G of soda ash, along with instructions. It will scour approximately 4lbs. of cellulose fabric.