Rit Dye works beautifully on many washable fabrics including: Natural fibers, such as cotton, silk, and linen; Synthetics such as rayon, nylon, and acetate; Blends will tint evenly but will not achieve full color. For maximum coverage, use the washing machine technique. Use 1 bottle for 2 pounds of dry fabric - or 1 pound of fabric for dark or bright dye colors. It is not recommended for 100% polyester, 100% acrylic or fabrics with special finishes, rubber backing, washable only in Cold water, or labeled Dry Clean Only. If in doubt, test a small swatch. Do not pour dye onto fabric. Wear rubber gloves. Rit will stain fiberglass and plastic. Recommended for wash machine, sink, or stove-top dyeing. Not for tub dyeing. Wash dyed garments separately in cool water. Good Housekeeping Seal of Approval Purple.