Acrylic airbrushing yields coarse surface - what am I doing wrong?

The paint is probably drying before it hits the surface, hold the brush a little closer to the model or rub the surface over with a paper towel to remove the dust.

Paint too thick, spraying distance too large, inadequate thinner. Tamiya's acrylics are best thinned with their own thinner or isopropyl alcohol. Ethanol/methanol may prevent the acrylic resin from polymerizing correctly.

In my opinion, you should use Tamiya thinner exclusively to thin Tamiya paint. Others will tell you different, and I'm sure they've had good luck with other media; however, I initially thinned their paint with iso alcohol and had terrible luck with it, including the coarseness you describe. I gave it up, switched to ModelMaster and Polly Scale for awhile. I had paint lifting problems with those two, returned to Tamiya about six months ago, but this time using their thinner. I love the stuff, now. No lifting, nice coverage, no roughness.

Just my advice.

OK, I'm quite sure some of the problem was distance, I was holding the airbrush quite far back for maximum coverage. The hull is bigger so I possibly held it back further than the turret hence more roughness there.

I'll try the Tamiya thinner from now on. Any suggestions on the ratio of thinner to paint?

Could this possibly be caused by moisture in the compressor? I noticed more moisture than usual when I purged and wondered if this roughness was a symptom of that.

No, your moisture stayed in the compressor. Moisture in the line would produce a spitting airbrush. Depending on your setup your line should come off the air source and go up to the ceiling and then to your airbrush; or you can get a moisture trap but that's not your problem.

You can start with 1/3 thinner and 2/3 paint. Experiment with different distances from the subject till you get it correct. It has to go on wet, you'll see a sheen. Too wet and you'll get a run/paint drip. hth

The Keeper (of too much crap!)

The proprietary thinner probabbly works great. I rely entirely on isopropyl with Tamiya, but I also thin the dickens out of it, like 50/50 or even a little more, and lay down mist coats. The idea is to have enough thinning medium so that there are no individual droplets of paint on the surface, which is ther direct cause of the roughness, since Tamiya acrylics dry so fast. The indirect causes have been mentioned elsewhere in the thread--too high pressure, too great distance, inadequate thinning, and you can even have a problem with too high ambient temperature.

It's a trick worth mastering to lay on the mist coats one after the other without getting runs from too much liquid paint on the surface at one time. It's entirely possible the Tamiya thinner doesn't require this technique, though I've heard people bitch about this problem for years. I don't even use Tamiya normally, since other types of paint are more tractable, but it does offer the most opaque acrylic white I've found, and I also use the yellow over the white to maintain paint compatibility.

Mark Schynert

I have always been told not to use water with Tamiya acrylics. Always use their thinners (or an equivalent whatever it might be). Only use water to clean brushes.

David

It depends on how far you spray from the surface, air pressure, how long you stay on the same spot and sometimes even the airbrush you use.

With acrylics I usually spray a 50/50 mix at 10-15 psi, however I found that the better way to find the right mix is to try first the wrong ones :)

It's difficult to see if the paint isn't thinned enough because you see the rough surface only after, when looking closer; instead it's easier to see if the paint is too thin because it doesn't cover well or it runs. So when I have to test the right thinning for a new brand of paint or a new thinner I take a scrap model (always use plastic, not paper or cardboard) and thin the paint until it runs. Then I only have to add a little paint to the mix.

My 0.02

Tamiya's thinner is isopropanol with maybe some negligible other chemicals thrown in. I've used 70% iso with good results. hth

The Keeper (of too much crap!)

Well said, a lot of times folks forget that your plastic is non absorbent and testing on paper will give you unusable results. Cheers,

The Keeper (of too much crap!)

Yeah, I probably should have mentioned that perhaps my technique just never meshed with Tamiya thinned with alcohol. I've read in various places that Tamiya's thinner contains a flow agent.

I too thin 50/50. I've never been able to get good, consistent results with any other ratio. I run my Paasche VL at about 35 psi. I'm always open to new ideas, but so far this works for me. Thanks for the info, Mark.

Cheers, David

Yes water is not for thinning properly, the paint is water soluble not water based.so just use it for washing out.

Thinned the paint with Isopropyl and moved the brush closer. Results were great! Thanks guys!

What is your air PSI? More than 20 psi? You may have hard water in your tap. Tamiya always recommends you use their thinner. Bill wesley

Art

compatibility.