This lady has a brick and mortar store and has been using Wilton food colors in her bath bombs...
http://www.youtube.com/watch?v=AOY7QFOVv6AI've also heard of people using small amounts of regular food dye (the brand you generally find in grocery stores) in their bath bombs as well... umm... let's see... it's the McCormick brand. The ingredients listed are: water, propylene glycol, FD&C Yellow 5, Red 40, Blue 1, Red 3, and 0.1% propylparaben (preservative)
I'm not exactly sure what sort of effect these colorants will truly have on the skin because once they get spread into the bath water, the concentrations decrease dramatically... please let me know if I'm wrong on what I am now going to assume:
Say I make up some bath bombs using the McCormick brand food dye:
I make a batch using 1/4 tsp of dye and the batch yields 3 large bombs.
A normal bathtub holds about 30-50 gallons of water, but I'm going to use 5 gallons as my example:
5 gallons is approximately 80 ounces and 1/4 tsp is approximately 1/24 of an ounce. Doing the math, I found that the total percentage of the food coloring is about .005% of the bath water. Then you have to divide that number by the number of bath bombs made ('cause they're big, I assume you'll only need 1 bath bomb per bath) and it comes more to the amount of .0016% of the bath water. And mind you, this is using a 5 gallon example while bath tubs can hold as much as 10 times more water.
I would however still not recommend use by those who are sensitive to the ingredients...
More info:
FD&C Red 40 (approved for cosmetics):
http://www.ewg.org/skindeep/ingredient. ... d06=702431FD&C Yellow 5 (approved for cosmetics):
http://www.ewg.org/skindeep/ingredient/ ... _YELLOW_5/FD&C Blue 1 (approved for cosmetics):
http://www.ewg.org/skindeep/ingredient/ ... 6C_BLUE_1/FD&C Red 3 (not approved for cosmetics):
http://www.ewg.org/skindeep/ingredient/ ... 26C_RED_3/Propylparaben (limited use in cosmetics):
http://www.ewg.org/skindeep/ingredient/ ... YLPARABEN/I did a quick search on McCormick's site to see which of the colors contain Red 3 and only the Red food dye contains it... so the blue, green, and yellow colors should be more than ok to use!