I saw someone use a marker to write on cakes....can i use icing colors? i cant find the markers...in black, only colors. ...and should i use a brush or tooth pick?
Americolor does sell a 2 pack of black foodsafe markers. We get them from CK Products.
Yes, you can use the gel colors to write on a cake. I like to use a thin angled paintbrush. Depends on how dark you want the color, you can either use the gel straight or diluted slightly with water or vodka.
I would not use gel straight as it takes forever to dry.
The best way to make a quick-drying edible "paint" is to mix gel paste color, dried food color, or luster dust with a few drops of a neutral-flavor liquor, such as vodka or everclear (although, in a pinch, I have used vanilla flavored clear rum on cakes and cookies that were vanilla flavored).
If you do not have those on hand, a clear, alcohol-based extract, such as artificial vanilla, lemon, or almond can also be used.
The amount of alcohol needed is very little. It evaporates (well, like 99.999% of it does), leaving behind just the color.
A new paint brush can be used to paint the desired details. I use artificial (poly) artists paint brushes with plastic handles as they can be run through the dishwasher and come in a wide array of bristle shapes and sizes. I run the through the dishwasher after purchase and before ever using on cake, just to make sure they are safe.
Hope this long (detailed) reply proves helpful to you!