Name: Ron

Message: Paula, Hello. We are trying to remove dye from solution dyed nylon 6 and 6,6 carpet without harming the properties of the nylon. FYI, the nylon is dissolved in a solution of acid when we would like to remove the color. Any ideas? Our ultimate goal is to obtain clear or white nylon from recycled carpet.

This may or may not be possible, depending on the specific dye used in each sample of nylon. Manufacturers typically change what dye they use to produce a certain color without notice, and not all dyes can be removed. Some colors will remain unchanged no matter what you treat them with.

Since you are decolorizing nylon, I strongly recommend against using ordinary household bleach (hypochlorite). Bleach will damage or destroy nylon. Instead, I recommend that you use a sulfur-based discharge agent. There are a number of different sulfur-based discharge agents, but all produce similar effects (effects which are quite different from the results of an oxidative bleach, as it happens). The page on my site that you should look at is "What chemicals can be used to remove dye?". Scroll down to the section on "Reductive discharges".

The different chemicals that can be used to discharge dye must be used according to specific recipes, in order to obtain maximum effectiveness. Once you have located a suitable recipe, you must experiment to determine whether it works for your situation. Most discharge agents are used under alkaline conditions. The one that I know can be used under acidic conditions is Formosul, also known as Rongalit and as Colour Index Reducing Agent 2. You can order Formusol from PRO Chemical & Dye in Massachusetts, and you can order Rongalit from Jacquard Products in California. (For contact information for these and other dye chemical suppliers, see Sources for Dyeing Supplies Around the World .)

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