Originally Posted by Photo Engineer
Sandy, I use food color from the supermarket. I have to use more surfactant because the colorant has some antagonistic properties to proper spread.
I would also suggest erythrosine as a very strong magenta colorant and very water soluable. I've used it, but it is about $25 / gram. But OTOH, you only need about 100 mg to make 100 ml of solution.
"McCormick Assorted Neon Food Colors" has 4 dyes in the kit. One of the bottles is FD&C Red #3 and from my research on the net is erythrosine.
Hope this helps,