I made a rainbow cake. I used the americolor electric colors. I colored my buttercream (made with real butter, half&half, clear vanilla) to match the layers of the cake. However, the electric blue would not become the same color as the cake layer. It was a sky blue - never would turn "electric" - no matter how much color I added. The cake layer was the perfect electric blue color. Also, the purple worked fine in the cake and buttercream.
So what is it in the buttercream that caused the electric blue not to work?
I'm not sure about your specific situation, but I have noticed that when I try to color butter cream with blue or black, it looks good at first, then starts to look almost separated and you can tell the color isn't completely saturating.
I have noticed it more when using butter cream that has even some butter in it than all-shortening.
Hmm. Maybe next time, I will make a small batch of buttercream with shortening only for the electric blue. I've seen electric blue icing that is the right color, so it's got to be one of the ingredients. I was leaning toward the milk, but maybe it's the coloring in the butter.
I guess I could try two experiments - One with shortening only and one with butter/shortening with water. Maybe that would find the "culprit'!!
Well if you do, let me know!!!
Yes, it's the butter in the icing recipe that is causing the problem. I agree w/the suggestion to make up a small batch of all shortening bc for blue.
See, combining blue (coloring) and yellow (butter) creates green so you will not get the results you were seeking.