I Accidentally Used Moldy Paint – Will It Turn to Be a Problem?

A lot of things can go wrong during a DIY painting project. Have you just realized that you accidentally painted a surface using moldy paint? You are right to be worried. Not only is mold toxic, but it can also cause significant property damage that is quite expensive to repair.

Do not panic. This article will help you determine the next best step after using moldy paint. All is not lost.

When is it okay to use moldy paint?

Considering how long you expect your paint job to last, knowingly using moldy paint is not advisable. However, if the mold contamination has not advanced too far, you might get away with it. If the moldy paint you used does not exhibit any of these signs, your situation may not be as bad as you thought:

  • Visible film or clumps of mold
  • Strong moldy or rancid odor
  • Condensation beads on the lid

Paint that has a strong odor and condensation beads under the lid is way past its prime and should be discarded. If the paint you used had not suffered extensive mold infestation, then there isn’t any need to worry.

Challenges Associated with Moldy Paint

The effects of using moldy paint differ depending on the degree of paint contamination. Where the mold colony had not proceeded for a long time, you may never even notice the difference. If the moldy paint you used had condensation beads on the lid, the mold contamination had likely been progressing for a long time.

If the moldy paint you used had condensation beads on the lid, the mold moisture undoubtedly did a number on its quality. The accumulation of mold and moisture causes paint to lose its viscosity and glossy sheen.

Using paint that has lost its sheen and viscosity will have marked effects. The paint will be too thin to cover the surface effectively. You will have trouble spreading it on the surface and will likely end up with colored streaks instead of an even coat. Aesthetics aside, moldy paint (dilute or not) has other side effects. It will produce a lingering smell that is very tough to get rid of.

The most dangerous aspect of using moldy paint is inhaling the toxic fumes it gives off. You are likely to be exposed to these toxic fumes even if you paint in a very well-ventilated area. These fumes have been proven to increase the risk of respiratory issues like cystic fibrosis, chronic obstructive pulmonary disease, lung cancer, and pneumonia.

The danger does not end there. Once the paint dries, it will be more likely to develop mold and mildew as opposed to non-contaminated paint.

How to recognize moldy paint

The best way to avoid using moldy paint ever again is to recognize the warning signs before you get started. Unfortunately, mold does not always present itself in an obvious way; that is probably why you failed to notice it before you began painting. It is wise to dispose of paint cans that present any of the following signs.

1) Musty Smell

When mold begins to grow in your paint can, it emits microbial volatile organic compounds. These compounds combine with the moisture in the paint and create a harsh odor. The terrible smell is capable of worse than offending your nose. Microbial volatile organic compounds pose a serious health risk to anyone who inhales them for long periods.

2) Rancid Smell

If the suspicious can of paint emits a rancid smell that reminds you of sour milk, you should not use it. It likely has been contaminated by bacteria, which accelerates the mold’s growth. The sour smell is generated by the colonies of mold and bacteria that feed off each other and grow as time passes.

Bacteria are typically introduced into the paint due to failure to seal the can correctly. Repeated opening and closing of the can could also introduce bacteria in the can. In some rare instances, bacteria are introduced into the paint during manufacturing. Expired paint is also much more likely to develop mold and bacteria.

3) Discoloration

The discoloration is the most obvious sign of moldy paint. If your paint has a dark green or black film on its surface, you should not use it.

4) Clumps

Where the mold infestation has not spread aggressively, you may not find a moldy film. Instead, there may be clumps of mold present. These clumps could be on the can’s lid and walls or in the paint. The clumps of mold are typically found on the lid alongside condensation beads that drop into the paint as your open the can.

Causes of molding in paint cans

You likely want to avoid being in such a tricky situation again. The best way to achieve this is by ensuring any cans of paint you buy will not be compromised by mold. Protecting your paint cans from mold is not a hard task. You only need to avoid these common mistakes that most people make:

1) Poor Storage

Your paint should be stored according to the manufacturer’s instructions. The rule of thumb is to keep paint tightly sealed in a dry place.

Storing your paint under extremely hot or cold temperatures will accelerate its deterioration. The solvent that ensures your paint remains liquid freezes or evaporates under improper conditions. If your paint can is opposed to unfavorably high temperatures, this solvent evaporates and condenses on the walls and under the lid.

The condensed water combined with the air in the can create the perfect breeding ground for gold. If you live in a region with extreme weather conditions, do not store your paint in the garage unless it is climate controlled.

2) Improper handling

Bacteria increase the odds of mold growing in your stored paint cans. While mold could develop naturally in expired or poorly stored paint, bacteria are usually introduced to the paint due to improper handling.

You can avoid introducing bacteria into your paint can by resealing any leftover paint tightly. After opening the paint can, do not place the lid on a dirty surface. It is also advisable to seal the tin as soon as possible because exposing an open can for too long could also cause bacteria contamination.

3) Expired Paint

Paint past its expiration date begins to degenerate. Separation of the solvent from the paint pigments or damage to the paint can cause mold to contaminate your paint can. Your paint should be good for two to ten years, depending on the type and brand.

How to use moldy paint

As we mentioned, not all moldy paint must be discarded; some may be redeemable. It all depends on how far the mold infestation has progressed. Acrylic paint is best discarded if it shows any signs of mold infestation. Other types of paint should not be used if they have developed numerous clumps of mold or a very overpowering odor.

If you have no choice but to use moldy paint, there are precautions you should take to minimize the damage. Your first step should be stirring the paint to ensure it retains a uniform consistency and glossy sheen. If the paint turns out to be watery, you will have to apply multiple coats and settle for underwhelming results.

You could also purchase a paint mold inhibitor if you are worried that the mold in the paint may continue to grow.

How to Reduce Odor Caused by Moldy Paint

The best way to get rid of a moldy smell after using contaminated paint is a fresh coat of paint. If that sounds like too much, there is a way to reduce the smell without repainting. Pour vinegar into a spray can and apply it on the contaminated surface. Once the surface is saturated with vinegar, prepare a 1:10 bleach solution and wash the surface. Rinse the surface with clean water and allow the area to dry.

If the odor persists after cleaning with vinegar and bleach, your only option is to repaint.

Ways to prevent mold in paint cans

There are several ways to ensure your paint cans are not contaminated by mold. These include:

  • Purchasing high-quality paint with low water content
  • Storing in a cool, dry area
  • Purchasing the right amount of paint to avoid leftovers
  • Ensuring leftover paint does not sit for too long
  • Discarding paint after the expiry date


Accidentally using moldy paint is a mistake any DIYer could make. It does not necessarily mean that you must repaint your walls. Where the mold infestation was so minimal that you did not notice the mold spores or a pungent smell, their damage is likely minimal enough to ignore.

The right course of action depends on how moldy the paint is and where the surface is located. Using moldy paint in the kitchen, bathroom, or outdoors increases the risk of mold spreading because these regions are frequently exposed to moisture. Repainting ensures that the moldy coats of paint are sealed away from further moisture exposure.