I think you need to add a bit more violet. This has happened to me also and after I added a little more violet, it brightened right up.
Violet is opposite of yellow on the color wheel. that means, when you combine the two colors, you get gray/brown. What happens in the icing is that you are essentially dulling the yellow. It's not going away. If the icing is strongly yellow, it's going to be somewhat more difficult. There will be a very fine line between taking the edge off the yellow and creating the gray/brown color. It's easier to accomplish if the yellow is very pale. Then you don't notice the graying so much.
I have MUCH better luck using a bit of white food color. Wilton has some, but it's very expensive. The best per-ounce deal I've found is in airbrush colors. Or, you could seek out a pharmaceutical supplier and get the titanium dioxide in a powder. That's what white food color is...titanium dioxide and water or some other carrier. I like the powder best because it doesn't soften the icing.
As I cant get Crisco I make an all butter BC. I read if you added a touch of violet it brightens the icing and makes it whiter.
I tried this today and my icing looked like dirty snow what did I do wrong?
Maybe we have really yellow butter here in NZ?
I have the same problem and keep trying it thinking I am crazy because so many people here swear by it. I don't know if I use too much or too little violet or if it's just my eyes, but I tell you, all I ever get is dirty looking icing when I try that violet trick. I think the yellow color looks much better than the 'dirty' white.
I also have not had luck with the Americolor white coloring. I find you need to add so much white to see a difference that it ends up changing the consistency of the icing.
Let me know if you have any luck when you try again in the morning.
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