Painting help for a newbie

A couple of quick thoughts on your questions-

I don't sand anything that doesn't need it- no point in making more work for oneself.   That said, I might buff the entire surface of a model with a 1200 to 2000 grit paper if the surface is rough or pebbly, or only on certain panels or sections to give a slightly different texture than on surrounding areas.   Since your working on a car, then you might need to buff the plastic to high luster so that the following paint has the smoothest surface to cling to.   Smooth surface is essential to high-gloss finishes.

As for the paint...   sounds like the paint is too thick to use under normal pressures.   I've been thinning paints down more than usual and using more light layers to build up color.   Tamiya paints can be tricky to fine-tune to one's tastes, I find that Model Master paints are easier to use and more consistent in their thinning.

If paint adhesion is an issue, then wash every sprue and part with warmish water and detergent to remove the mold release agents and let dry before doing any assembly.   Then , give the entire model a good wipe-down with isopropyl alcohol before painting to remove fingerprints and such.

You might get better responses if you ask this in the cars forum as there's some car-specific paint tricks that I don't use.

Thank you very much for your response.  I am washing the models first, and them wiping down with Testor Plastic Prep.  Sorry but one other question...  The model body I'm painting is molded in orange and I'm painting it in Orange.  Do I need to primer?

I only prime if the plastic has a strong color that will affect the overlying paint's color.   Orange on orange should be OK...    but something like white paint over orange plastic would certainly get a light grey primer.

Hope that helps, we love answering questions.

Thank you both for the quick and informative posts.  I have soooo many questions, but I need to start writing them down as I tend to forget most of them......

I prime to improve adhesion.  I personally think priming is a good idea whatever the color of the plastic.  Yeah, you can sometimes get away without priming depending on what kind of paint (some adhere better than others) but I still recommend primer.

Sounds like you're using a Paasche VL double action - right?  I've used that model for over 40 years with excellent results using all types of media.  I usually start thinning at 50/50 & shoot at 20 psi, but it can vary.  Often it's good to shoot at a higher pressure for large areas, and lower pressure for very thin washes/fine line work.

Also, remember that the VL has a "trigger adjustment screw" that will make the AB act like a single action.  This can be very helpful for precision  work.  Find the pattern / amount  / line you need & set the screw to that amount.

For spraying primer, I'd tend to use less thinner, more pressure & larger volume - 30% thinner 35 psi & half open on the trigger.  Keep the AB moving & spray about 12" away.  I really like to prime bare plastic if I'm going to use acrylics.  At work I use lacquer, and that bites the plastic quite well, so no primer needed.  However, finding lacquer for hobby work is difficult.

Good luck with the new AB

Think i will try priming more to improve my painting.  Anyone know what store bought cheaper primer will work with Tamiya Acr and MM Enamel?  Thank you for reminding me of the adjustment screw.  This is my first model in years and my first with an air brush.  Makes it easier for me to learn to use the Paasche.