How to Thin Automotive Paintsby H.C. Hisel
Thinning automotive paint is necessary before using a spray gun to apply the paint. The paint needs to pass easily through the gun's nozzle to achieve an even color across your auto's surface. If the paint is too thick, you won't have an even flow out of the airbrush gun and the gun will continually get clogged. Thin your automotive paint to a more appropriate consistency before you attempt to airbrush for an easier application.
Prepare paint for thinning. Set aside the appropriate amount of paint you will need for your project. It is best to set aside all of the paint you will need in the project all at once. This will ensure all of the paint is thinned evenly and in the same fashion. Place the paint in a clean plastic container.
Fill a spray bottle with paint thinner or lacquer. These items are sold at any hardware supply store. You will need to choose the appropriate thinner or lacquer to mix with the type of auto paint you will be using. The contents of your paint will define what type of thinner you will use. Follow the guidelines on the back of each thinner container to choose one that works with the contents of your paint brand. Applying the thinner using a spray bottle will make for easier handling; it will decrease the chances of adding too much thinner and ruining your paint.
Combine the thinner into the automotive paint. There is no exact measurement of thinner that should be used. It varies widely within brands and even colors. It is best to follow the manufacturer's outline for an approximate calculation. For the best results, spray a few squirts of thinner into the paint at a time while stirring with a mixing stick. This will allow you to monitor the paint's consistency as you go, rather than initially guessing the amount you will need.
Mix the thinner and the paint. Once you have reached a point of appropriate consistency, mix the combination well. To test the consistency, pick up the container of paint and gently tilt the container side to side. Before adding thinner, the paint would have a slow reflex, lagging slightly in drifting off the sides of the container after you tilt the container. Once you have reached the right consistency, the paint will drift at about the same speed that you are tilting the container. Keep in mind you do not want your paint to be too thin, which will show up as the movement of paint in the container being quicker than your tilting motion.