Name: Krysten
Message: Hi!  I've spent a lot of time on your websites lately and successfully tie-dyed a batch of cotton onesies with Procion dyes.  (Yay!  Thanks you!)  I have a lot of dye left over - I poured it all into jars and hope to use it again.  (I didn't use urea.)  How long will it last?

If any soda ash has gotten into your Procion MX dye, then it will only last about two hours, because soda ash makes the dye react quickly with fabric OR with the water it's dissolved in. If there is not even a drop of soda ash in your dye yet, then it will probably last about three weeks at room temperature, or longer if you refrigerate it. (Some people have highly alkaline water that causes the dye to hydrolyze quickly in water, but most water supplies are fine.) As it ages, the dye will gradually get weaker and make slightly paler colors.

Once your Procion MX dyes have completely reacted with the water, so that they are no longer any good for dyeing cotton, they can still be used for dyeing silk or wool, using vinegar or another acid instead of soda ash. (See "Fiber reactive dyes on protein fibers".) They'll be good for that for as long as they remain liquid and appear to be unchanged, long after they are unable to react with cotton and unable to react with silk in the presence of soda ash.

I'm glad you were able to use my site to successfully dye your baby clothes. It's a lot of fun, isn't it?

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