I am going to teach a class and after we got it all set up then they said, 'Are the dyes non-toxic?' I taught my daughters girl scout troop when they were little which was more than a day or two ago! Non-toxic wasn't a concern then. So, I want to make sure I do this right! I was up till 3 am reading your forum. What is 'urea' and what is it used for?

Procion MX type dyes are considered non-toxic when used properly, that is by people who are old enough and sensible enough not to put the dye in their mouths or squirt it on each other. However, the Jacquard Products tie-dye kit does not carry an ACMI Non-toxic Seal on the label. The same ingredients are found in the Rainbow Rock tie-dye kit (produced by a different manufacturer), which does bear a nontoxic label with a reference to the ASTM D-4236. This does not guarantee that a product is completely non-toxic, but it does indicate that it is free of known acute or chronic health hazards other than those indicated on the label.

You will need the MSDS pages if it is necessary to officially show how toxic or non-toxic the dyes are. This must be supplied by the manufacturer of your kit. Since you are using the Jacquard Products kit, you can look at this link to the MSDS pages at Blick Art Materials [PDF]. Here is a link to the MSDS for the Rainbow Rock tie-dye kit [PFD], which contains the exact same ingredients. [Link updated June 18, 2012.] It is easier to read and also less alarming, but it's for the same product by a different manufacturer. MSDS pages are also provided by PRO Chemical & Dye and by Dharma Trading Company, which are the two most popular (and economical) sources of Procion MX dyes.

You will be mixing the dye powders with water in advance, won't you? I recommend that you mix them up one or two days before, for the sake of convenience, if you are using a kit that includes the soda ash as a separate presoak, as the Jacquard kit does. Some tie-dye kits include the soda ash mixed in with the dye powder (I think including the Tulip and Rainbow Rock kits); since the dye will last less than an hour after it is mixed with the soda ash, these dyes must not be mixed up until the children are ready to use them.  I don't want children to mix up the dye powders, because the most hazardous thing about the dyes is the way it's so easy to breathe the dye powder, if you're not careful, and children rarely are. If you breathe dye powder repeatedly, you will be at risk of developing an allergy to the dyes; if this happens, you will not be able to use this particular type of dye any more, although there are alternative dye choices. People who have an allergy to a particular type of reactive dye may develop symptoms of asthma whenever they are exposed to the dye powder. This is more likely to be a problem for people who work in the dye industry, of course, but we want to be careful to make sure that it does not happen to us, too. Wear a dust mask when mixing up dyes, and allow the lids to be off of the jars of dye only for a short period of time.

It's important to wear gloves when applying the dye. A friend of mine tie-dyed shirts with this same type of dye with her two sons, none of them wearing any protective gloves at all. They found that the soda ash was so drying to their hands that it caused tiny splits in their skin; these splits were not painful, and they healed in a few days, but it was an entirely unnecessary problem. I have never experienced anything like that, because I always wear gloves when tie-dyeing, and I wash or at least wipe off my skin if I spill soda ash on it. The occasional hole in the glove will result in stains on the skin, which last for two or three days, but not any noticeable harm.

How old are the children you will be working with? If you have time, mail-order some nitrile or latex gloves in size small (for middle school ages through small adults) or extra-small (for younger children), or call around to see if a medical supply store in your area carries small sizes. If the only gloves you can access in time are the one-size-fits-all gloves at the hardware store, you might need to give the children rubber bands to hold them on at the wrists. Reusable rubber gloves that are sold for dishwashing, at the grocery store or the pharmacy, are even better, because they cover more of the arm; you can always find these in size small. Many adult women wear size medium. The cheaper brands of disposable gloves include many defective gloves, so be sure to buy more than you think you will need.

Urea is a humectant, which means it helps the tie-dyed items to stay damp longer so that the dye has time to react with the fiber. The dye requires some moisture to complete the reaction, but urea is considered optional for dyeing. It is included in the MSDS for the Jacquard tie-dye kit, so the urea is probably already in the dye bottles. It's not something you have to worry about, in either case. Urea is not harmful at all. I use a skin cream that contains 25% urea for dry skin.

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