My thinner I use is a homemade recipe based on the MRH acrylic painting guide. Its cheap to make. I make the high performance thinner by the gallon. I actually need to make 2 gallons next time as I use it as my go to airbrush cleaner as well.
http://model-railroad-hobbyist.com/node/30953
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PLAY-IT-SAFE THINNER FORMULA (makes 32oz/950 ml)
- 53% distilled water (500 ml)
- 21% vendor’s airbrush thinner (200 ml)
- 21% acrylic flow enhancer (200 ml)
- 5% acrylic retarder (50 ml)
Total cost is about $30 for one quart (950 ml) of thinner, or about 3.1 cents per milliliter. For flow enhancer, I like Vallejo’s airbrush flow improver [4-3]. It’s on Amazon here: amzn.com/B00QD780G0. For retarder, I use Golden’s retarder [4-4], amzn.com/B0009HAB58.
HIGH-PERFORMANCE THINNER FORMULA (makes 33.8oz/1000 ml)
- 55% distilled water (550 ml)
- 20% butyl cellosolve (200 ml)
- 20% Armor All Auto Glass Cleaner (200 ml)
- 5% acrylic retarder (50 ml)
Total cost is about $18 for just over one quart (1000 ml) of thinner, or about 1.8 cents per milliliter. I get butyl cellosolve from Amazon in 8oz (237ml) bottles for about $15: amzn.com/B017Q3PM0Q. The butyl cellosolve helps the paint go on smooth and level well, and helps it adhere to plastic and metal. This is thinner works very well as an airbrush thinner for the paints in this booklet. It’s similar to Createx High Performance reducer/thinner.
SUPER-ECONOMICAL THINNER FORMULA (makes 32oz/950 ml)
- 74% 80-proof (40% ABV) vodka (700 ml)
- 21% Armor All Auto Glass Cleaner (200 ml)
- 5% acrylic retarder (50 ml)
Total cost is about $13 for one quart (950 ml) of thinner, or about 1.3 cents per milliliter. This thinner formula is the most economical – it’s made from cheap vodka, chemically known as ethanol. As a thinner, this mixture is quite funtional, but not quite as superb as the butyl cellosolve formula above. This formula is especially ideal as a thinner for brush painting. Do be aware this thinner formula is the most flammable of the three home-brew formulas given, making it more risky to use with an airbrush (but still much less risky than lacquer thinner)."