A paint reducer is a product designed for thinning paints and primers. It allows thicker products to be used as sprays without stopping up the sprayer or creating uneven coats of paint. Most car paints must be mixed with a reducer before use.
The ratio of paint reducer to paint varies depending upon the type of paint used. Most paint labels contain instructions for the ratio of paint to paint reducer if the paint is to be used in a sprayer. The effectiveness of some paint reducers is influenced by temperature, so application should be consistent with the manufacturer's directions.