Sorry for rezing topic but this seems the logic place for the question.
How do I create a matte surface?

Rub my model with 1200 grit sand paper?
I have a model ready for decals after which I was planing on flat coating it and applying Mig pigment(desert/sand). But I guess the pigment will fall off over time. Is the flat coating enough to hold the pigment in place?
"DESERT DUST: The pigment is applied directly to a matt surface. If the surface is glossy, the powder can disappear with time."