Latex paint is water-based and contains latex. Latex paint is commonly used for interior walls because it is a fast-drying paint. Because latex paint is water-based, cleanup is much easier. Spills and brushes can be cleaned with regular water, rather than paint thinners or removers. On the other hand, since latex paint is water based, it can become watery over time. If you wish to thicken latex paint because it has become watery, or you just need a thicker coat of paint to cover prior colors or wall damage, latex paint can easily be thickened with hydroxyethyl cellulose.
Transfer watery latex paint into a bucket large enough to hold the amount of paint to be thickened, plus at least an extra 1/4 of the bucket for added thickener and stirring. If the container currently holding the paint is at least 1/4 empty, the paint does not need to be transferred.
Slowly add the cellosize hydroxyethyl cellulose to the paint by pouring it in. Cellosize hydroxyethyl cellulose is a gelling and thickening agent derived from cellulose.
Stir the paint as you add the thickener. Continue adding and stirring until the desired consistency is achieved. The amount of cellosize hydroxyethyl cellulose added should not be greater than 25 percent of the amount of latex paint. Too much thickener will make the paint too thick to paint and spread.