Moldy Paint in Paint Can- Signs & Is It Okay To Use It?

Opened an old paint can but it has mold in it? Wondering if it’s still good to use?

In this guide, you will learn:

  • If Paint can Get Moldy & if Can You Use Moldy Paint,
  • How To Use Moldy Paint If You Absolutely Need To & Precautions to Take,
  • Ways To Prevent Mold Growth In Paint Cans.

Can Paint get Moldy?

Mold can appear anywhere- on your clothes, in the basement, in food.  Not only can it cause structural damage and costly repairs, but it is a hazard to your health.

Given the right conditions, mold can even grow in your Paint Cans.

There are various signs of moldy paint and these are the most common ones:

Musty odor

Paint smells musty and the mold begins as mildew emits gasses known as microbial volatile organic compounds (M.V.O.C).

The moisture combined with the stagnant air and dark corners (depending on where the paint is stored) contributes to the strong odor.

Which in itself can be a threat to your health should you be exposed to prolonged inhalation.

Rancid Odor

Moldy paint gives off a rancid smell like sour milk. It is a combination of bacteria and mold that grows and feeds off each other overtime.

In rare circumstances, this bacteria may have been accidentely introduced to the paint during the manufacturing process.

It could be the lids were not sealed properly leaving it exposed to the air and other sources of bacteria that could potentially contaminate the paint.

Another reason for moldy paint is that the paint was opened and closed repeatedly.

Another possibility is the paint has exceeded the expiration date, depending on the type of paint.


A film of mold directly in the paint itself will easily discolor and destroy its quality.

It is normally black or dark green depending on how long the mold has been allowed to grow.

This is what moldy paint looks like.


This is found on the insides of the tin or bucket itself. Clumps of mold can also sit on the lids as you open it.

Normally you will find beads of condensation that will drip down the lid and into the paint itself. Small clumps of mold can be found with this.

Can You Use Moldy Paint?

The best way to determine if you can use it is if the paint emits a strong rancid smell or has visible mold as you open the tin. It is best to discard it if that is the case.

However, sometimes this isn’t always needed.

Mold needs time to grow and if there is a small clump in the paint or on the side of the tin then you can use a spoon to scoop it out and discard it.

It is often advised to stir the paint with a stick and see if it holds its smooth glossy sheen.

If the paint hasn’t been opened in a long time and is contaminated then high amounts of condensation and mold will collect in the paint causing it to lose its smooth gloss.

This process waters the paint down causing it to lose its viscosity.

Should this happen the paint won’t be thick enough to coat the walls; instead you will have streams of colored water running down the wall.

There are common problems if you decide to use moldy paint (which isn’t advisable anyway). Even if you get good ventilation in the area you are painting, this will not stop the lingering smell that is caused by moldy paint.

Prolonged inhalation of the fumes that mold gives off can lead to respiratory problems such as Chronic Obstructive Pulmonary Disease, Cystic Fibrosis, Pneumonia and even Lung cancer.

Most Common Causes Of Mold In Paint Cans

Incorrect Storage

This is due to storing the paint in either a very cold or hot basement, near a washing machine, boiler or a radiator.

These conditions speed up the paint’s deterioration.


Mycotoxins, which are toxic compounds found in certain types of mold and fungi.

This is usually caused by incorrectly handling the paint and allowing dirt to mix in; repeated use and not shutting the lid so that it is airtight.

Temperature and Time

Paint contains a solvent that gives it it’s liquid form, this freezes at below 50 f and evaporates at high temperatures.

At high temperatures, condensation forms on the inside of the tin and the stagnant air can create mold to form inside paint cans.

Another reason is using the paint which is past its sell-by date; paint lasts anywhere between 2 to 10 years.

Mishandling During Manufacture

This is due to incorrectly sealing lids during the processing stage.

Prolonged exposure to the air causes bacteria to get inside paint cans which can contaminate the paint.

It loses its purity and spoils after time which can create perfect conditions for mold spores to grow.

How To Use Moldy Paint If You Absolutely Have To

First of all, if your acrylic paint is moldy it is best not to use it.  But if you do decide to use it there are precautions to take dependent on the smell and the location of the mold itself.

If the smell is so overpowering it is best to discard the paint and if numerous clumps have formed in the paint itself that is another reason to discard it.

You can test it first by stirring the paint. Paint that has sat for a long time and hasn’t been opened will settle, keeping its smooth glossy sheen.

Spoiled and contaminated paint will be very watery.

You may need to apply a second or third coating because when the paint dries it will prolong the problem as opposed to solving it.

This is on the premise there are no clumps of mold found in the paint itself.

Another alternative is mold inhibitor for paints that you can purchase.

How to Fix Smell On Walls If You Have Used Moldy Paint?

If you have used Moldy Paint and your walls has started to smell, often the best solution will be to completely repaint the walls.

However before that:

You can spray vinegar on the moldy paint on the walls and saturate the area.

or Wash with a mild bleach solution of 1 part bleach to 10 parts water.

Rinse with plain water and a clean sponge.

If after doing this the smell still persists – It’s time to repaint it.

How To Prevent Mold In Paint Cans

Store paint in a cool dry place and away from heated areas.

Make sure you don’t exceed the expiration date.

Avoid reusing paint that has been sat for very long periods of time and been exposed to condensation.

If you only need a small area painting then purchase a small tin so that it is used up and doesn’t go to waste.

Choose high quality paints- the low quality ones have a higher water content making them susceptible to condensation.

In conclusion…

There is no hard and fast rule about whether to use paint that has mold. It all depends on how much or how little there is.

If there is a large amount of mold in a small tin then it is best to discard it.

However, if a small clump of mold is found on a standard 5 Litre/1 Gallon Bucket then it is not worth throwing it away and can be used in most cases.

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