Problem with Tamya acrylics

There could be a couple of reasons for this problem.
First of all you may be cutting the paint too much. But this will usually just cause the paint to run. With most Tamiya acrylics, I don't cut them at all depending on the consistency of the paint.
Second, and this one is more likely, because you are using canned propellent you are not getting a constant pressure. The longer you use the propellent, the colder the can gets. The colder the can gets the more your pressure changes. The more your pressure changes the less the paint is going to atomize and cause small splatter or pebbling.
If you can, borrow a compressor from another modeller and see if the problem continues.

Sounds like the paint is drying too fast. The atomized paint droplets partially dry as they travel to the surface. This shows up as a granulation and creates the sandy surface. Either use the airbrush closer, turn down the paint flow, use a thinner mixture of paint, or add a retarder to the mix. I also use water as a thinner rather than the alcohol. The alcohol evaporates too fast for my liking. Liquitex makes an acrylic airbrush medium that I have been using with great success. Mix a little with your paint when thinning. (I usually fill the small Aztek cup with paint then add a couple of "brush fulls" of the airbrush medium) The paint flows better and does not dry as fast. The thinner mixture should lay the pigment down cleaner for you. I have run several types of acrylics for different applications through the Aztek. The Tamiya paints dry the fastest. I use both acrylic thinner and airbrush cleaner to flush between color changes or while I am refilling the paint cup just to keep it clean.
My Aztek works fine, and I like the control I can get with it. It has been a steady workhorse for about 6 years now. I have shot acrylic, enamel, watercolors, guache and ink through it. Each media acts differently and experimentation with each will provide the best results.

Good luck
Mike

Mike, you hited the bull's eye. I was using the airbrush to far and wasn't thining the paint properly.
Thanks for the help. :)

Great call Mike.

Thanks guys, it was my pleasure. 'Bout time I paid some back into the bank.....

Glad I could help.
Mike