I was wondering if I could use just regular food coloring? Or do I have have have to use the gel coloring? Im trying to color my icing, its a camoflauge army helmet cake, So Im probably going to be using black, brown, and green. any advice will help!
If you use gel colours you wont use as much as the liquid . I would add some cocoa to my icing when making it, to give you a darker base to start with so you need less colour.
I learn't this after I made an Army green cake (on one of my first cakes) and I ended up using a few bottles which then changed the consistency of my icing. 
HTH 
I would suggest using the gel. If you want dark colors you'd have to use so much of the liquid, it would mess up the consistency of your icing, like the PP said.
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