Paint comes off after airbrushing

[brad.p]

I am busy with a scratchbuilt styrene building and have painted it with Tamiya acrylic matt colours diluted with about 50% acrylic thinners. After having airbrushed it, it appears that the paint does not stick to the styrene properly and I am not sure whether I have mixed the paint incorrectly or am doing something wrong in my airbrushing technique. If I scratch the painted surface lightly, the paint peels off without any resistance.

Any comments/suggestions would be welcomed.

 

[macjet]

Did you wash the plastic first? If not you may still have mold release from manufacturing. A ten minute bath in soapy dish water should help. If that doesn't work you may have to try a product such as Plastic Prep (very nasty stuff though).

 

[CP9302]

As macjet says, you should always wash the plastic before painting. Mold release and oils from your skin can cause paint to not stick.

You should also always prime things before painting them.

I have never used Tamiya paints, but thinned 50% seems like a lot to me.

Plastic Prep should not be needed for a styrene model. But things like delrin handrails will need it.

 

[GAPPLEG]

I prime everything before painting. Weren't Tamiya paints supposed to be used straight up ? I've never used them but I thought I've heard that.

 

[jbaakko]

I've never used Tamiya, but I have had an issue with paint rubbing off from handling, like it never fully sealed. Wost part in my case was the fact that the primer did not wear off.

Possibility that the paint dried to much before it hit the model.

 

[GWT&P]

I agree with washing and primer before painting.

 

[brad.p]

Hi guys and thanks for all the replies - I am new to the hobby and especially scratchbuilding and airbrushing. The comments all make sense and I will experiment further and post any findings here.

Josh, I am interested in your comment that it was perhaps too dry when hitting the model - what would cause this and how does one prevent it from drying before reaching the model?
______________________________
Brad

 

[jbaakko]

Too much air, not enough paint, or holding the brush too far away from the model.

 

[JimmyG]

I guess I have a similar question. I tried to airbush black acrylic paint on a silver painted hopper recently. The paint did not cover very well. Do I need to strip the hopper first? If so, how do you get silver paint off? I might have thinned it too much. Your answers/comments are welcome.

 

[IronBeltKen]

Jimmy, the best and safest way I've known about is to let the body soak in 91% isopropyl alcohol for several hours, then scrub the paint of with a 'stubble' toothbrush (where you chop the the bristles off until they're only 1/8 inch long).

I avoid brake fluid like the plague - it makes some plastics really brittle where it crumbles like a potato chip when you touch it!

 

[macjet]

Lift Off is also a plastic safe paint remover.