What situation would call for putting plastic dye packs in the washing machine at high heat?

Question

Someone told me he does this at high heat in the washing machine for tie-dying but I can't seem to find anything about this online or if it is even an advisable thing to do. He mentioned the dye packs were made of high density polyethylene.

Answer 1

The only plastic throw-in-the-washer dye packs I've seen have contained direct dye, which is an inexpensive, low-quality dye which washes out of clothing rather quickly unless set afterwards with a cationic dye fixative such as Retayne. Direct dye is the same kind of dye that's found in Rit dye that bleeds so badly in the laundry and fades so quickly. It requires high heat to fix as well as possible, ideally around 88 degrees C (or 190 degrees F).

I never have a situation that calls for this sort of dye, because I always prefer using fiber reactive dyes, which give brighter, longer-lasting results, without requiring high heat or the cationic dye fixative. Unlike direct dyes, fiber reactive dyes are easily set with soda ash, and are extremely wash-proof and long-lasting. They are easy to use in the washing machine at low to medium temperatures.

Dharma Trading Company sells direct dyes in dissolvable dye packs; their name for them is "Industrial dyes". They say, "Industrial Dyes are used in Laundries, Prisons, Jails, Hospitals, Industrial sites or anywhere that large quantities of clothing, rags, towels, or whatever need to be colored or color coded." They add that these dyes are inferior to Procion dyes, but convenient when cheapness is more important than quality. Their washfastness can be improved with a cationic dye fixative such as Retayne, but this treatment increases their susceptibility to fading by light.