Acrylic paint thinning.

[Ron Pearcy]

I've taken the plunge and bought a compressor and airbrush kit after brush painting since recently getting back into the hobby. What is the best way of thinning acrylic paint for airbrushing, I mainly use Tamiya and Humbrol acrylics.
Thanks in anticipation.

 

[fubar57]

You'll get as many thinning recipes as replies Ron. For Tamiya I use their thinners, IPA, or distilled water at 2:1 paint/thinner at 20psi. I have also used 1:1 at 15psi

 

[mikewint]

I'll cast my vote along with Geo. I strongly believe you should stick to a manufacturers thinner as many paint formulas, while necessarily similar, are also proprietary. Having said that I have used 70% Isopropyl alcohol and blue windshield washer fluid.
As to dilution the general rule of thumb is "the consistency of whole milk", which is a judgement call.
There are members here who use 50-50 automatically so in a sense there is no fixed rule

 

[fubar57]

....and some go down 30:70 or less allowing pre-shading to show through. When it comes down to it. make notes of you mixtures/air pressures, do some testing and go from there. I've been using an AB for about two years and have just started straying for 2:1

 

[MIflyer]

If you will take a look at the Finescale Modeler link I recently provided you'll find that among the free downloads is an article on using acrylics in air brushes.

 

[Ron Pearcy]

Thanks fellas, appreciated.

 

[Builder 2010]

The only one that thins nicely on alcohol is Tamiya. If you attempt to do it with the others (e.g., Vallejo, Life Color, Model Masters) they tend to clump up and clog the brush and generally make a big mess. I've had decent luck with either Vallejo's proprietary thinner (for their paint) and Testors Universal Acrylic Thinner. I bought some expensive AK thinner and used it with another brand and it was a disaster. I've been using 91% Isopropyl Alcohol with Tamiya for years and years with great results. I buy it at the drug store and it's many, many times cheaper than Tamiya's own.

 

[fanghawk]

....and some go down 30:70 or less allowing pre-shading to show through. When it comes down to it. make notes of you mixtures/air pressures, do some testing and go from there. I've been using an AB for about two years and have just started straying for 2:1

This is an excellent point that can't be stressed enough. Practice, experiment, practice...and take notes. When I last used an airbrush in the early '80s, it was a single-action, siphon feed, with enamel paint. It took a lot of pressure from the compressor to get the paint out regardless of how much it was thinned. Wasn't a lot of variation possible and the paint tended to go down pretty thick. With the gravity feed, dual-action brush I'm using now with acrylics, it works at such low pressures that I sometimes forget to crank the pressure back up. I was trying to spray a light misty coat of Future on part of my model so I could tape it and I couldn't figure out why the airbrush seemed to be struggling so much. Future is a bit thicker than the normal paint mix I've been using and I'd forgotten to turn the pressure up. You can thin the paint way down and use low pressure to get really fine lines, you can mix it at 1:1 or 2:1 paint to thinner and crank the pressure up just a little to get great coverage...there are a lot of options. So experiment, practice, and keep track.

 

[Ron Pearcy]

Cheers mate. Had my first practice session and seemed to get a good mix. I diluted Tamiya acrylic 1:1 with Tamiya X20 thinners. No problems with getting fine lines but not so sure about coverage on larger areas when I pulled the brush back away from the surface. I'm using paper as test surface so I probably need some plastic model pieces to get a good representation. As you say,practice,practice.
Thanks again.

 

[fubar57]

I've got an old 1:48 Harvard that I use for testing. Right now, any left over paint I have in the cup is used to practice Luftwaffe mottles

 

[mikewint]

I probably need some plastic model pieces to get a good representation

Restaurant-type take-home boxes make excellent practice models. They are free, come in various sizes, and have both flat surfaces and complex curves to practice on.

 

[Ron Pearcy]

Brilliant idea.

 

[fubar57]

This is my test bench. With left over paint I practise mottles....

 

[Wurger]

 

[Chip B.]

Brilliant!