How to Thin Rustoleum Paint for Spraying
- 1). Pour 1 gallon of Rust-Oleum oil-based paint into a bucket that holds at least 1½ gallons, to allow room for stirring.
- 2). Measure 6½ ounces of acetone in a measuring cup, pour it into the paint and mix it thoroughly with a wooden stirring stick.
- 3). Test the mixture by filling the spray gun and spraying a small amount on a scrap piece of metal. You may also test it using a viscosimeter, also called a viscometer. Following the viscosimeter's directions, pour the recommended amount of paint in the cup and time how long it takes to drain out. Compare the results to the viscosity recommended for your spray gun.
- 4). Add more acetone or more Rust-Oleum to make the mixture thicker or thinner, measuring the amount you add. Write down the amount you add so when the viscosimeter reads correctly or the paint performs the way you want in the spray gun, you can thin future batches by the same amount.
Source...