----- Original Message -----
From: radius158

Is there a reason to 1)sandblast a styrene kit before painting or
2) prime a styrene kit if it is already grey ???? such as an
intermountain kit
----- Original Message -----

I have been modeling (tanks, ships, and aircraft) for 35+ years and I had never heard of grit blasting a plastic kit until I started model railroading last year. I have never had a problem with adhesion of enamel or acrylic model paints on either styrene or polyurethane resin _so long as_ the the kits were properly cleaned immediately before painting (gentle washing with dish detergent and and old, soft toothbrush, followed by a rinse and air dry). Likewise, while priming is not uncommon, I think it just hides detail and is unnecessary with proper preparation. I only prime surfaces that I've worked or modified to make sure there are no seams, cavities, or glue gobs, and even then I use the final color or another shade from the same line to contrast with the plastic. Most of this paint is removed anyway during final wet sanding. I would never use one of the "primer" paints - which seem to be quite thick - on plastic.

The only issues I've had have been with vinyl tank tracks or vehicle tires and some metals. A scrubbing wash of the vinyl with mineral spirits followed by a stiff detergent scrubbing seems to have cured that problem, while metals can do with a light 600 grit sanding followed by a solvent/detergent wash. Acrylic paints also seem to stick to metals better than enamels, for some reason.

I will admit that there have been a few kits back in the '80s and early '90s from the old Warsaw Pact countries and China made from some unknown polymer that felt greasy even after solvent washing and would not hold solvent cements, super glue, or epoxy - let alone paint. Howeve, I doubt you'll be running across any of them.

KL