Hi! I am having trouble getting light gray and tan colors. When I mix a little black color or fondant in to my white fondant I end up with a purple (ish) fondant instead of pretty light gray. Same with tan. Mixing brown into white seems to give me a weird color... not a light tan. I am stressed over this! Thanks for any help you can give :-)
Best way I found to get a light gray is to mix a tiny bit of pre-made (purchased) black fondant with white fondant and/or gumpaste. Light tan, you can try the same technique with chocolate fondant. Good luck. I found that some black gels tend to have a purple tint, hence the outcome you are getting.
AGrey - add brown Tan - add green
I'd switch brands. A little black should make a light grey.
I have no trouble getting a nice gray by adding a little black to my white Fondarific fondant. For tan, I would do as bsy bug says and mix chocolate and white. I've had terrible outcomes with brown food color, regardless of the brand but get a beautiful ivory by adding some real vanilla extract.