I made a white fondant-covered cake with colored dots. I attached the dots by painting them with a little water first. (Was that a bad idea?) The colors on the dots "ran" into the white fondant.
Now I'm making a white buttercream-covered cake and I want to add dots, but I don't want the colors to run. Do I just press them into the buttercream with no water? When the cake warm to room temp (from the fridge) will the colors run? Will the dots slide when condensation hits the cake?
if the colors ran, it sounds to me like you may have put too much water on them. All you need is a tiny bit.
As for attaching fondant to buttercream, I allow my buttercream to crust then immediatly attach the dots. Don't wait too long because it will cause an indention on the buttercream