Airbrush help--primer on plastic?

[SpaceMouse]

I am building an MDC kit steamer and am painting it with a Badger 150 airbrush. I think I have figured it out a litlle, I can get a soft spray that evenly disperses a light spray of paint.

The metal part of the engine where I baked on primer looks great. But on the plastic part the paint doesn't stick well and is blotchy. The paint looks like it has stuck then when you make the next pass, the airbrush blows the paint off the plastic into piles.

Now it is well cleaned. I thought it might be that I used Pinesol to remove the lettering, but it did the same thing on Little Guy who came naked.

I am using artists acrylic paint and they work out pretty well with a brush--but everything takes a few coats.

I'm wondering if I need to stock a supply of different color primers to pre-treat plastics.

I'm also wondering if I can somehow sand or steel wool the high spots without messing up the details too badly and recoat.

[Anonymous]

Chip
You don't want to sand it for sure. The scratches will show through. Floquil sells a Paint & Decal remover. You can also try denatured alcohol. It may soften the Acrylic primer. If not, try giving it a long soak in a strong Tri Sodium Sulphate solution (TSP). You can find that at any paint department. It's used for dulling and cleaning walls before painting. Whatever chemical you use, wear gloves and use an old stiff tooth bru***o scrub off the paint.

For some reason the paint didn't adhear into the plastic. There might have been mold release or some other kind of contamination. Sometimes soap will not remove silicone. Giving it a scrub with denatured alcohol will remove silicone and finger oil. Yes finger oil. Even though your hands and clean and dry, there is still oil present. Use white cotton gloves or latex WITHOUT the power coating. Plastic gloves may have mold release on them. I have seen this problem come up in auto body shops. We banned silicone liquids at my shop.

Now, what kind of plastic is it? I would assume it's styrene. Next time spray the inside of the shell to see if it's going to adhear. If it peals off again, it could be the paint. Maybe too thin or contaminated. Try using Floquil, but very light coats. Floquil is lacquer based and laquer thinner will melt styrene if it is applied too heavy. Just a light coat is all you need.

[orsonroy]

Gary's right on target: clean the model with alcohol and keep it clean during the entire painting process. You might also want to change paints, to see what works best for you. Personally, I like Polly Scale and Krylon for all my spray painting needs.

[dano99a]

Ditto on the above, additionally it could be that the paint is too deluted (too much water or thinner)

Another possibility,( but I think what the gentlemen above stated is the problem)
is that if you don't have a trap on your compressor you'll get water in the line which will in turn mix with the paint (deluting it more) and or make the brush "spit"

I like using the badger model flex paint. it's air brush ready, no deluting required. [:)]

hope this helps