Name: Melinda
Message: To heat set the food coloring dye (Kool-aid), can I use an iron since I don't have access to a microwave in the classroom and a vegetable steamer takes 30 minutes?

No, unfortunately that will not work at all well. An iron produces dry heat, which will not do a good job for setting acid dye. You would have to continuously steam the same section of the fabric for a while in order to set the acid dye on the silk. It would be much easier to bring a hot plate and a vegetable steamer to the classroom. Or, you can treat the project much as you do works produced on paper. If you do not steam the dyes, you cannot wash the fabric, but you can allow it to dry and show it as a non-washable artwork. Or, you can take the dry silk fabric home, and steam it there before returning it to the classroom to show the students their results.

What kind of fabric are you using? You probably already know that you cannot use food coloring dye to dye cotton. Only silk, wool, and nylon will work with acid dyes such as food coloring.

If you need to be able to heat-set with an iron, rather than a steamer, I would recommend that you use fabric paint, rather than dye. If you use transparent fabric paint, you can get some neat effects with sun-printing, as one possible idea. You can do a sort of tie-dyeing with pigment dyes, which are actually not a dye at all, but a form of fabric paint. See "Fabric Paints: a different way to color fibers". You must allow the paint to dry thoroughly, preferably overnight, before ironing it.

Fabric paint can be set with an iron because the heat is causing a glue to bond to the fabric. This takes considerably less time (and moisture) than it takes for steam to allow acid dyes to form hydrogen bonds to attach to silk or wool.

Also see:

Using Food Coloring as a Textile Dye for Protein Fibers
http://www.pburch.net/dyeing/fooddyes.shtml

How can I tie dye with Kool-aid or food coloring?
http://www.pburch.net/dyeing/FAQ/drinkmix.shtml

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