I'm using a NEW can of ModelMaster Modern Desert Sand 1963 and when I'm spraying the plastic the paint adheres to the flat areas but not the raised areas even with the plastic primed. I don't know what is causing this. Could it be that I'm spraying to close?

It's a condition known in the auto modeling world as "panel line seperation". Thats where the paint pulls away from sharp edges and panel lines like fender seams door and trunk lines. The best way to avoid this is by sneaking up on the final finish.

Start with a primed clean model.

Begin by painting "mist coats" that's where you hold the can back a ways and just fog the paint on. Wait a few minutes and mist on another coat. Do this a few times until you have a uniform light coat of paint on the entire surface.

Wait about 15 minutes then begin with what are called "wet coats". Hold the can closer and give the model one good coat of paint. Wait another 15 minutes and do it again.

The trick is to not be heavy handed on the wet coats so as to disturb the good base laid down with the mist coats. If it occurs more paint will NOT help. Let the finish cure, sand it and start again with the above procedure.

G