Name: Steve
Message: Dear Paula,
I don't know where I can order the following food colorings:
indigotine blue #2 CI 73015
erythrosine red #3 CI 45430
tartrazine yellow #5 CI 19140
I want to order some of them. Can you tell me where I can order them (in USA)? Thanks so much!

You can buy food-grade tartrazine by the ounce from The Coloration Station. They don't appear to have indigotine or erythrosine, but it might be worth calling them to ask.

I don't know of another ordinary retail source for these food colorings. You should be able to get them from wholesale food additive suppliers (about which I know nothing), or from a chemical supply house. The problem with most food coloring retailers is that they do not specify which dyes are in their colors in their catalogs. You will probably need to contact them by telephone to determine whether or not the dyes you seek are contained in various products. Perhaps you will be able to read the ingredient labels at a cake decorating supply store to find your dyes. I've found tartrazine in artificially flavored and colored drink mixes at the grocery store, but no indigotine or erythrosine.

Sigma Aldritch's online chemicals catalog contains all three of these chemicals, but their MSDS for indigotine indicates that it is not food-grade, and the same is no doubt true of the others. "For R&D use only. Not for drug, household or other uses." That would rule out artistic dyeing purposes as well.

Organic Dyestuffs (Orco) lists FD&C colors. Use their contact form to inquire about purchasing.