I have a large sheet cake to ice red. I have never been able to get large amount of buttercream really red. Should I ice white and do a layer of red over that. Any tips on how to get a large quantity of icing really red would be greatly appreciated.

I use Americolor Super Red in the  Elmo cake you ca see it in my gallery. A little goes a long way. Color more than you actually need, because its hard to math the color if you need to make a new batch. I find the color darkens as it sets, so its a good idea to color ahead of time and let it sit awhile before you add more color. Also use gloves the red can stain your hands.HTH