i have a blue cake that i want to airbrush red letters onto. Will this work or will is just turn out purple?

Yup...it will turn purple. Anytime you mix colors on the cake you get the blended color.... yellow+red=orange..blue+yellow=green..... love the effect when making a rainbow with just 3 colors!

any suggestions on doing lettters without airbrushing, i am not comfortable writing with icing. I have horrible handwriting and its worse on a cake

you can cut a piece of white and airbrush them onto that than cut them out.??? I cut all my lettering out of Modeling chocolate works FABULOUS!!!!!!