Can you paint over mildew?

Can you paint over mildew if using mildew resistant paint? This question is frequently asked by homeowners who wish to cover the walls and other surfaces of their homes that are discolored by mildew, destroy it and prevent its return. The answer to the question is “no”. Any paint, even anti-mold paint will not kill the mold already on the surface. It will however, prevent you from seeing where the mold is growing and spreading from making it much worse.

What is mildew?

Mildew is a common word used to describe mold and its discoloration. The mildew can appear in patches of brown, green, or black color and materialized as fuzzy, slimy, or powdery patches over the painted surfaces. Mold is a parasitic fungus and can eat through and into porous painted surfaces. The mildew can eat through the painted surfaces causing wood to rot and masonry to crumble.
Mold develops in areas with warm, moist and humid conditions where there is poor ventilation specifically in bathrooms, laundry rooms and kitchens. It can also be noticeable on exterior walls where there is poor air circulation and minimum direct sunlight such as walls that are north-facing or shaded by trees.

Many times mildew is difficult to distinguish from simple dirt. You can test a surface whether it is covered with mildew or dirt by placing a drop of common house hold bleach (5 % sodium hypochlorite) on the affected surface. A mildew stain will bleach out in a minute or two while dirt will remain intact.

What to do if you can’t paint over mildew?

Painting over mildew will only provide a temporary solution to the complex problem. The mold will continue to live and spread beneath the paint making the situation worse. The best way to fix the problem is to destroy the mold from the source before painting over the surface. It is of course, impossible to completely remove the mold from the affected surface especially wood. However, a professional can be called out for assistance in sanding the wood to remove the mold but be careful as sanding molding wood can be hazardous since it releases thousands of tiny mold spores into the air.

The remedy for mildewed surface:

The Paint Quality Institute suggests mixing a disinfecting solution of three quarters of water to one quarter bleach. It is also recommended to use fresh bleach since the bleach loses effectiveness over time.

Warning: Since bleach is a chemical compound, it can burn eyes and skin so make sure to wear eye protecting goggles and rubber gloves when using the solution. Apply the mixture using a sponge or spray and allow it to stand for approximately 30 minutes before rinsing with plain water.

If the mildew is on surfaces that are plastic, aluminum and/or chipped enamel, test a small area first before applying the solution as bleach can damage the material.

It is also advisable to ensure protection of outside greenery from bleach solutions by covering them with clear plastic. Remove it as soon as the treatment is completed and do complete water rinse of the plants.

Which paint to use?

Many paints used on bathroom walls and exterior walls include mildewcides to make the paint mildew resistant. Mildew preventers such as biocide barium metaborate prevent the growth of new mildew from developing. However, they do not help in destroying the existing fungus. Paints with mildewcides should not be used on areas where children could suck or inhale the paint fumes such as windowsills, doorframes, etc.

Paints mixed with zinc oxide are more resistant to mildew than paint that contains titanium dioxide. Paints that include linseed oil are also prone to mildew as well as lower grade paints.

Mold sealants can also be applied to affected surfaces before re-painting. The paint seals the mold that cannot be removed and prevents it from growing and spreading. It also helps in repelling any future mold from appearing.

Mold resistance paint:

Home and commercial building owners can choose to use mold resistant paints in those rooms that are subjected to excessive moisture such as bathrooms and kitchens. Mold resistance paint can also be used in basements, attics and other areas that have been infected with mildew in the past. Paints especially designed to resist mold is easily available at most home building and décor stores. Nonetheless, these paints will not guarantee reproduction of mold but they will however, help prevent the problem from getting severe.

Before using mold resistance paint on any surface or wall, make sure that the area is clean, dry, and free from any type of mold or mildew. Make sure the mold sealant is completely dry before painting the surface.

How to prevent mold from developing on surfaces and walls?

Keep all surfaces clean from dirt, grease, soap scum, etc as these grimes are food for mildew to grow and spread.
Avoid leaving wet towels and other laundry items lying around the house.

Plants are good for keeping the air in our home clean but are also a source of mold. Make sure to keep shrubs and trees away from exterior walls to enhance air circulation and drying.

Use darker color paint on the exterior wall of your home as it has the ability to absorb more heat from the sun and dry faster after rain or dew.
Lessen the moisture level in the bathrooms by installing and running exhaust fans during and after showers.

Fix any leaks and other plumbing issues around the house to prevent the buildup of moisture which in result promotes the growth of mold.
Increase the air flow around the house by moving furniture away from the walls and leaving wardrobes open.

Paint on a cool day so mildew spores do not blow into the new coating.

Always remember, the easiest way to deal with mold is to use your own thoughtfulness. A musty odor and watermarks on the ceilings or walls are main indication of mildew so make sure to keep your house clean by using proper disinfecting methods.

Professional help for mildew:

Professionals always recommend removing and replacing any molded surfaces as soon as possible if you are unable to thoroughly clean it. Molds grow faster than you think and can be hazardous to your health as well as your loved ones. Exposure to high level of mildew can lead to severe allergies and asthma so keep your house clean by preventing mold from appearing.


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