How to Kill Mold & Mildew on Latex Paint

In just a few years' time, the beauty of a fresh coat of house paint may be marred.

How Mold and Mildew Grow

This is because organic substances in paint serve as food for mold and mildew. Minerals (inorganic compounds) become trace nutrients. Fungi can release organic acids that add to the damage done. Higher quality paint is formulated with fungicides to fight mold and mildew; however, over time, fungus may still begin to grow. Using a commercial product or a homemade fungicide, mold and mildew can be stopped in its tracks. .

Learn the invasive growth habits of fungus, the "enemy."

Mold grows via spores to form mycelia. Like roots, these mycelia penetrate paint and may reach into the wood surface below. To the highest degree possible, the fungicide must reach beneath the immediate surface.

Understand why the best tool to accomplish the job may not be the right one.

Mercury preparations (such as phenyl mercuric compounds or mercuric acetate) make excellent fungicides; however, due to health and environmental concerns, less efficacious substances must be chosen for use in paint, especially for indoor surfaces. Mercury can invade the body through ingestion, skin absorption, or inhalation in trace quantities (causing acrodynia, a rare disease that causes painful extremities). Mercury is concentrated in the tissues of the nervous system and in red blood cells.

Heavy metals have been largely supplanted by proprietary organic formulations.

Maintain your investment. Periodically check painted surfaces to see if mold and mildew removal is needed.

Though fungicides are compounded in quality latex paints, protection against mold and mildew does not last forever. Cool, damp, and shady locations will hasten the growth of mold and mildew. Painted surfaces will require external application of cleaning/fungicidal agents. There are proprietary formulations (often expensive) that can be purchased to remove mold and mildew, however it is possible to formulate your own fungicide using the following ingredients:

1/2 cup of 5% chlorine bleach 1/4 cup laundry detergent 1 gallon water

Once applied, let the formulation sit on the surface for about 5 minutes before rinsing. If using a power washer (for outdoor painted surfaces), do not apply too much pressure, as this can cause paint to chip or peel.

Things You Will Need

  • Bucket
  • Brush
  • Ladder
  • Household bleach
  • Household detergent
  • Power washer (optional)


  • Some prefer to use Borax, rather than bleach plus detergent. Follow safety precautions and use in a manner consistent with labeling instructions.


  • Mix and use your fungicide with caution. Although household bleach is a familiar item to us all, in the cleaning process, painted surfaces will probably need spraying or brushing down. Bleach and detergent in this setting become primarily a risk to the eyes. Asthmatics may wish to be cautious when using bleach.

About the Author

Vincent Summers received his Bachelor of Science degree in chemistry from Drexel University in 1973. He furthered his education through the University of Virginia's Citizen Scholar Program program, taking many courses in organic and quantum chemistry. He has written technical articles since 2010.