Dharma Dyes Proffesional Textile Detergent is a less expensive alternative to Synthrapol.
Use is exactly the same as Synthrapol - 1/4 cup per washing machine load, rayon, hemp, etc. and 1/8 cup (1 oz) for silks or front loading wash machines. Best used with HOT (140°F or higher) water, both as a pre-wash to clean and prepare fabric for dyeing, get rid of fingerprints, oils, silk worm gum, and other things that cause the dye not to adhere well, and as an after-wash to get the excess dyes out. Also used, in the case of tie-dye, batik, or other situations where multiple colors are involved, to hold the dye out in suspension so it doesn't re-deposit where it isn't wanted. Gets out excess dye better and faster than normal household detergents so that items are safe to wash with others in the future. Is pH neutral like Synthrapol, so it discourages "setting" of loose Fiber Reactive dye particles where they are not wanted, and is easier on wool and silk than high pH detergents.