100 - Celebrating a century. Cotton. Wool. Nylon. + more. Non-toxic safe for sewage & septic systems. Rit Will Dye: Cotton. Linen. Rayon. Silk. Wool. Nylon. Conforms to ASTM D-4236. ritdye.com. Before dyeing visit ritdye.com for detailed instructions and a library of over 500 color recipes. Made in the USA of US & imported materials.