tamiya paint thinning

Tamiya acrylics deliver the best results when well thinned. If you use an alternative thinner such as denatured  (ethyl) alcohol or lacquer thinner, as noted above, you can thin it to the extreme. However, you cannot do this with the standard X-20A acrylic thinner. Go much beyond about three parts thinner to one part paint and it will bead and run, much like it does when thinned with water. There was a time when people used to recommend two parts paint to one part thinner, but that time has passed. Most of the range, with a few notable exceptions such as white, red, yellow and orange, have a very dense pigment load and can be thinned very liberally. 

If using metallic Tamiya acrylics, you should not really try to thin much more than about three parts thinner to one of paint otherwise the metallic particles (which are pretty large in Tamiya paints) tend to fall out of suspension very quickly and clog your airbrush in very short order.

Everyone above seems to recommend 12-15 PSI, which is fine for a gravity feed brush, but for a Paasche VL, which tends to need more air, I would suggest starting in the 15-18 PSI range and adjust as required.

To echo Real G, I use lacquer thinners as well - though I use either Tamiya of Gunze lacquer thinners for the actual thinning duties. They're a bit less hot and stink a lot less. Then I clean up with Windex and hardware store lacquer thinner.

I also eyeball the stirring stick...after awhile you get a sense of what works and what doesn't.

Another thing about Tamiya paints (especially with lacquer thinner) is that you can reduce the stuffing out of it. I'm talking like 5, 10% paint for very thin filter coats. So there's really no danger with over-thinning, except you'll have to make that many more passes. 

thank for the advice

I have airbrushed Tamiya acrylic paints using hardware store lacquer thinner with excellent results.  The paint sprays just like an enamel and dries almost as quick.  I get none of the clogging problems that typcally plague airbrushed acrylics.  Yes it stinks to high heaven, which defeats one of the advantages of acrylic paints, but it really works.

The thinning ratio varies from color to color for any paint brand, but my unscientific method is to use a cut down popsickle stick to mix the thinner as it is added to the paint.  When the color of the stick is readily visible at the edges, the paint is thin enough.  (Kind of like looking at an oil dipstick.)  But really you have to experiment to find the best ratio for yourself.  I like my mixes to be on the thin side, which means more passes to get full coverage, but the paint goes on smoothly and I can control the color saturation better.

I typically use 12-15 psi when airbrushing, but again, the type of paint and the color will affect this.  Metallics will require a higher pressure due to the heavier pigments, but I never go over 25 psi.

As always, your mileage may vary.  Good luck!

Neal

Depends a lot on your environment.

Personally I START at a ratio of 2:1 thinner to paint with Tamiya, and adjust as necessary. Air pressure will vary, but I'm usually around 12-15 psi.