Help!!! I made buttercream today and coloured it with royal blue colour. Colour mixed really well. Then piped it onto cupcakes. When I had a look about an hour later, the colour had streaked throught the buttercream!!! It looked almost curdled even though the texture of buttercream was still smooth?? It looked as if the colour was seperating from the buttercream?? Buttercream recipe is butter, powder sugar,and a bit of milk.
These were for my nephew's birthday party, and I didn't have time to start again! I had to deliver them as is!! Any advise would be greatly appreciated.....I don't know what went wrong.... I've coloured buttercream in the past and have never had this happen.....

did you use a liquid color?? It seems like the color didn't incorporate with the butter. You know water and oil don't mix? Just a guess as i haven't encountered this once the icing is on a cake.

Actually yes I did use liquid .......which I have in the past, but maybe this time I used too much to achieve a dark colour.....I really should buy paste colour by the sounds of it ..... thanks for your response peg818....I assume liquid colour should never be used in buttercream???

paste color incorporates better then liquid and doesn't change the consistency of your icing.

It is probably because you tried to achieve a dark color that it didn't work as well as it normally does for you.

Thanks so much for your advice peg818. I see what you're saying. Looks like I'd better start buying paste colour from now on.