Procion is a brand of fibre reactive dyes. They are commonly used in tie dye and other textile crafts. They are dichlorotriazine dyes and were originally made by Imperial Chemical Industries. The brand name is now owned by Dystar, but, since the patent on the dyes has expired, many manufacturers around the world now make them.
^Horst Tappe, Walter Helmling, Peter Mischke, Karl Rebsamen, Uwe Reiher, Werner Russ, Ludwig Schläfer and Petra Vermehren "Reactive Dyes"in Ullmann's Encyclopedia of Industrial Chemistry 2000, Wiley-VCH, Weinheim. doi:10.1002/14356007.a22_651