Mold and Mildew Issues with Paints and Stains

We'll never completely solve the mold and mildew problem, but we certainly can minimize their harmful effects on us and our homes by being alert, addressing their causes, using products that don't support their growth and performing the routine maintenance that keeps them from becoming established.

Mold and Mildew Issues with Paints and Stains

There's been so much rain this year that we can practically see the mold and mildew growing before our eyes. Controlling these unwelcome visitors is a very complicated topic, so we're going to focus on the effects of mold and mildew on painted and stained surfaces, some of the ways to retard their growth, plus use of the best cleaners to remove them when the mold and mildew inevitably reappear, despite your best efforts.

As you know, mold and mildew spores are in the air and no structure is immune. Even a brand new home has potential mold and mildew issues unless all the materials that were used to build it have been treated before being incorporated in the structure, and that's a rare occurrence even in custom homes. So mold and mildew are a fact of life.

Why Worry About Mold and Mildew on Painted and Stained Surfaces?

We're familiar with the health implications of mold and mildew, but what are some of the other problems? Here are two to think about:

• Mildew on painted surfaces affects both appearance and coating performance. In addition to being unsightly, the presence of mold and mildew attracts more dirt and generally causes a loss of adhesion to the surface that leads to premature failure, including cracking, blistering and flaking.
• Mildew on wood can damage and weaken it because the cellulose and resins found in all wood species are nutrients for mildew.

Prevention

Mold and mildew are forms of fungi that grow on a variety of surfaces, both organic and inorganic, including wood, vinyl or aluminum, and on superficial surfaces such as dirt and grease. The best approach to prevention is to create an inhospitable environment. Whether it's on the inside or outside of your home, the number one growth factor for these fungi is water in every form, including moist air.

Fungi thrive in damp, dark places where there is little light or air circulation, so on the outside of your home, they will grow more vigorously in damp, shady areas than in the sun. Mold and mildew also will reappear if you paint over a surface where they are present. If you aren't sure, test for mildew by applying a few drops of bleach to the area. If the spots disappear, the discoloration is probably mildew. If it doesn't, it's probably dirt. Don't ever try to hide mildew on a painted surface by painting over it. The mildew will reappear very quickly and the problem will be much worse because the mildew has been sealed between the old and new coats of paint, requiring that the paint be completely stripped before recoating.

On the inside of your home, mold and mildew will thrive in bathrooms where there is a lot of moisture and little air circulation, so turn the fan on or open a window whenever you shower or bathe to create air movement and dry out the room. Don't forget other damp areas such as your laundry room, basement and kitchen, and remember to also monitor moisture levels in your closets. We bought an inexpensive moisture meter, and use it conjunction with our dehumidifier to keep the moisture content of the air at or below 55%, the point at which mold and mildew usually grow.

Coating Products and Prevention

The type of coating you choose has an effect on the growth of mold and mildew. Mildew grows more quickly on exterior alkyd flat paint than on semi-gloss or gloss enamels. It also grows quickly on products containing linseed oil. Generally, a premium quality latex paint will offer better mildew resistance than an alkyd based paint because it contains fewer nutrients for the mildew to feed on. Glossier paints are less porous than flat ones, so dirt and mold spores have more difficulty adhering. Darker colors will dry faster than lighter ones after it rains, so they're less receptive to mildew. Choose a 100% acrylic latex paint over a vinyl acrylic paint for better performance overall, including mildew resistance.

Paint and Stain Additives

Most of the better paints and stains contain one or more additives to reduce the growth of mildew. Discuss your particular application with the experts at the paint store and get their advice on the best one to use. Paints and stains that already contain mildewcides typically don't pose any disadvantages to the consumer because they've already been successfully formulated into the product. Some people are sensitive to finishes that contain certain mildewcides; however nearly all of the mildewcides used today are said to eventually break down into non-hazardous molecules that are re-absorbed into the environment. If you have any health issues, be cautious about the products you use.

You also can buy one of the so-called POP or "point of purchase" mildewcides when the situation calls for an extra measure of mildew protection. Some manufacturers will no longer allow the consumer to add the mildewcide themselves, and require that it be done by the professionals at the paint store. There could be certain disadvantages to their use:
1.    POP mildewcides can be expensive.
2.    POP's may be unstable with a particular finish and affect the color, become odorous and may slow or prevent curing.
3.    Special and costly disposal means may be required for unused portions.
4.    Other failures such as chalking, yellowing or color loss may be accelerated.
5.    The performance lifetime of POP's is typically shorter than mildewcides formulated into a finish.
To see if a POP mildewcide would be beneficial, discuss your project with the experts at the paint store.

Cleaning Products

If you do find mold or mildew, there are numerous special cleaning products to choose from. One note of caution: On the outside of your home don't rely on using the familiar general purpose cleaner trisodium phosphate (TSP). It actually is a source of food for mildew! Chlorine bleach mixed with water is the formula most commonly used to kill mold and mildew, but this formula alone isn't enough to do the job properly because

• The bleach solution has to remain on the surface for an hour to work, and most surfaces are primarily vertical, making it impossible.
• Bleach can turn the black spots of a mildewed area white without actually killing all the mildew. The organisms can still be alive and grow through the next coat of paint.
• Bleach and water alone won't remove dirt and stains.

Be never careful to never mix chlorine bleach with an ammonia-based cleaner as it triggers a chemical reaction that produces a gas called "chloramine" which is highly irritating to the lungs and causes coughing and choking.

The best approach is to use one of the special cleaning products formulated for this purpose. They usually are mixed with bleach and will kill mold and mildew on contact and remove dirt and stains without damaging glass, aluminum or painted surfaces. They can be used on surfaces such as vinyl siding and stucco, painted surfaces, wood, aluminum, concrete or cement block, stained or painted decks and fences and patio furniture. Read the label before you apply the cleaner and follow the instructions for proper use. Also, be sure you're careful around your landscaping and saturate everything before and after washing. Cover your delicate plants as needed.

Steam Cleaners

Don't forget steam cleaners for smaller projects such as outdoor furniture. They can be very effective in killing mold and mildew, and they're healthier to use and more friendly to the environment than chemical cleaners.

Roofs

Recently we've had several requests for removing mold and mildew from roofs. Although we want to be helpful whenever we can, we had to decline these requests because although we could clean the roof with our professional equipment, we didn't feel that we should do it because of our concern that the cleaning process could damage the roof. If you have this problem, please be very careful about how you address it. Using a pressure washer to clean a roof, no matter how low the pressure, is very likely to damage it and lead to premature replacement. If your roof has mold or mildew, please consult a roofing company and follow their recommendations on the best way to clean your particular type of roof. Just to be on the safe side, get more than one opinion.

We'll never completely solve the mold and mildew problem, but we certainly can minimize their harmful effects on us and our homes by being alert, addressing their causes, using products that don't support their growth and performing the routine maintenance that keeps them from becoming established. If you'd like help dealing with mold and mildew on your painted or stained services, just call us. We'll be happy to give you an estimate.