I found a bunch of old fibrec coldwater dye in my classroom
and am wondering if dye from the 70's is still good.

Fibrec was one of the original brand names under which Procion MX dyes were first sold to hand dyers. (I have a copy of the 1970 booklet, Basic Techniques of Tie-and-Dye with Fibrec, by Evilsizer and Flynn.) Procion MX were the first fiber reactive dyes introduced for use on cotton.

The reactive group on Procion MX dyes often lasts only a couple of years after purchase, though sometimes they may stay good for as long as five or six years. Your Fibrec dyes will no longer work as fiber reactive dyes on cotton or other cellulose fibers.

However, they can still be used as acid dyes on protein fibers, such as silk and wool, if they are applied with a mild acid, such as vinegar, plus some heat. See my page, "Fiber reactive dyes on protein fibers", for more information about using Procion MX dyes as acid dyes.


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