How to Thicken Semigloss Latex Paints

Updated February 21, 2017

If you apply thin semigloss paint to a vertical surface, excessive running and sagging could result. Fortunately, you can discourage this sort of problem by adding a thickening agent to the paint. Unfortunately, if you add the wrong type of agent, you'll likely ruin the finish. Many inexperienced novices recommend using anything from flour to baby powder to thicken semigloss paint. Avoid these sorts of home remedies and opt instead for a particular type of thickening agent that won't cause streaking or discolouration.

Pour 2 gallons of semigloss latex paint into a 5-gallon bucket.

Add a cup of hydroxyethyl cellulose to the paint.

Affix a 20- to 30-inch-long mixing paddle to your drill. Submerge the head within the semigloss paint. Start the drill and keep it running for at least three minutes.

Turn off the drill before removing it from the thickened semigloss paint.


Semigloss paint contains chemicals that provide it with a high level of sheen. Hydroxyethyl cellulose will thicken the paint without affecting the sheen. Other thickening agents may cause the sheen to dry unevenly. Don't try to mix hydroxyethyl cellulose with semigloss paint, using a wooden stir stick, or the sheen may dry unevenly.

Things You'll Need

  • 5-gallon bucket
  • Hydroxyethyl cellulose
  • Measuring cup
  • Power drill
  • Mixing paddle with a 20- to 30-inch shaft
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About the Author

Ryan Lawrence is a freelance writer based in Boulder, Colorado. He has been writing professionally since 1999. He has 10 years of experience as a professional painting contractor. Lawrence writes for High Class Blogs and Yodle. He has a bachelor's degree in journalism and public relations with a minor in history from the University of Oklahoma.