Yes, you can definitely color white chocolate with the Wilton Candy (oil based) colors.
That said, trying to get an extremely deep color, even with the candy colors, can lead to the chocolate getting "tight"--even at the proper temperature for temper, the chocolate will not be as fluid as you would expect and to get it to a good workable state, you'd need to add tempered cocoa butter. Vegetable oil is often used as a cheap substitute for cocoa butter and technically alters the balance of the ingredients so that it is no longer classified as true "chocolate".
Candy melts aren't chocolate, so you can add vegetable oil or paramount crystals to them to facilitate fluidity for poring, etc. and the candy colors will work well. The melts come in many colors, anyway, so you can start with a base close to what you want and not have to add too much to get the color where you want it.
Americolors has a product called Flo-Coat that can be added to gel color to color chocolate or oil based foods. I've used it with some success on white candy melts to get a dark navy blue, buy I still felt that the melts were too tight and didn't flow very well--but I haven't tried it on real chocolate.
Hope this is helpful.
Rae
Americolors has a product called
I love you, but your emergency is not my crisis!
They say that a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance.--Terry Pratchett (b.194
I love you, but your emergency is not my crisis!
They say that a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance.--Terry Pratchett (b.194