Spray Guns

• If you are using latex paint in a spray gun, you may find the sprayer is not working to its full potential because the paint is too thick. You might need to add water, or you may need to just adjust the tip or change the pressure setting. It's best to try the latter first, since adding water can affect the paint's ability to properly cover your painting surface. If you thin your paint too much, it may take additional coats to cover. Too much water also can affect the chemical composition of the paint, which means your paint job may not look as nice.
  
  Generally, you should add only 1 ounce of water to the paint and stir well. Add another half an ounce, if needed. Keep adding in half-ounce increments until you get the desired consistency you want. Be sure to stir well after adding water each time.
  
  

Old Paint

• If you have paint that is old and thick, even after stirring well, you may need to add water. Just like adding water to latex paint for a spray gun, adding water to an old can of paint needs to be done slowly because too much water can affect the quality of the paint. Read the directions on the can for thinning paint first. Usually, you can add 1 ounce of water first and then a half ounce, stirring well each time. Keep adding a half ounce at a time until the paint is the consistency of pancake batter.
  
  

Airbrushing

• Airbrushing is different because it uses a special concentrated artist paint (latex). Always read the manufacturer directions before thinning, but generally you can thin artist paint up to 50 percent to 80 percent with water. This affects the color of the paint, making it lighter as you add water, which may be your desired outcome. There are also special thinning agents just for airbrush paints, like Liquitex Airbrush Medium, which have added ingredients like retarder and Flow-Aid. These store-bought thinning agents are designed to keep the integrity of the paint as it is diluted; however, you should still consider trying water first, as it works well and is a more economical option.