Acrylic/Poly Thinner X20A 8.5 oz

This was literally formulated by chemists to work well with Tamiya acrylics and it does. It's not pricey at all considering how much thinned paint is actually used when airbrushing. Having around 3-4 bottles of this stuff should let you thin the entire range of Tamiya gloss acrylics and a good amount of the flat colors, too. It sprays perfectly smooth with a 1:1 ratio in my Iwata Revolution CR. I use 12 psi.

This is the best thinner possible for Tamiya acrylic paints. There is simply no better option. Yes, mineral spirits also work, but not as well. Using a 0.1mm airbrush tip, the default Tamiya ratio of 2 parts paint for 1 part thinner (this thinner) is perfect. There is no other word for it. It never clogged, sprays smoothly with no spitting, and doesn't run. Of course, I am building up light coats, but even then it is still amazing. My only gripe is how expensive it is compared to alternatives. Thankfully, one bottle of this can mix you 34 cups of 3/4 Tamiya paint at default ratio. That should be more than enough.

It's the only thinner I use for my airbrushing. I start at 1-1 plus or minus for most of my Tamiya acrylics and it always seems to hold true. Also use it on about a 1-4 to 1-3 ratio (thinner to paint) to get the so-called 'Air' products from Vallejo, etc. to flow and mix just fine. I don't tediously measure or count drops, I just eyeball it and get it close.There's no reason for me to try anything else. Great, effective product, decent price, and a good size container that fits on the hobby shelf. Exclusively used and highly recommended.