Sorry if this is a really stupid question but i am new to this I am making a 3D cat cake in about a week, their cat is a orange and white tabby and i am going to try and create this The Question is how do you make really white fondant or buttercream? I have made fondant and buttercream but it seems to be an off white and i want a pure white.
Also what is brush on colour? How do you do that?
Thanks for the help.

A shortening based bc will be slightly whiter than a butter based bc. You can also use clear vanilla to keep it really white.

Indydebi's buttercream is a nice white icing, and great to work with.

http://cakecentral.com/cake_recipe-6992-Indydebis-Crisco-Based-Buttercream-Icing.html

Sorry I can't help with the other information, but I'm sure somebody else will come to your rescue. And remember, there are no stupid questions, just questions we need answers to.

Use a very small amount of violet food coloring. It will cancel out the yellow of the butter. It is the opposite on the color wheel and it cancels it out. I use this when I really need a "white" icing. It really does work. Just be careful to put the tiniest amount (not even a full drop to start). You can add more if needed but it is easy to go from yellow to violet if not careful.

Joanne