Mildew is a fungus type of plant. Its spores are tiny and small movements of air will circulate them to all sections of a building. When the proper growing conditions become present, mildew growth starts and will continue until the conditions change. It will then remain dormant until these growth conditions return.
There are thousands of different types of mildew and the ideal growth conditions will vary. However, the types which are commonly found in buildings grow best during periods of high humidity, warmth, low light and poor circulation of air. The moisture may be present as a result of high humidity, flooding, spills, over-wetting during cleaning, etc. As long as the area is flooded with water or is saturated, mildew cannot grow because sufficient air cannot be obtained. Therefore, the growth may not start to take place until several days or even a week after the initial wetting.
A temperature range of 75 degrees F to 85 degrees F usually produces the most growth. Mildew growth will slow down as the temperature goes lower or higher. High temperatures will normally kill it.
Effects Of Sunlight
Sunlight is not needed to produce mildew growth, as it does not contain chlorophyll. It gets its food from the root system which works its way into the material on which it is growing. Mildew can only get its food from natural materials such as protein, cellulosic, etc. In a carpet, the protein material would be wool, the cellulosic would be jute or cotton. Not only is sunlight not needed for growth, if the direct rays from the sun shine on mildew, they will probably kill it. The only effect the circulating air would have is to reduce the moisture.
Mildew In Carpets
Mildew can be a problem on carpet, but it does not have to be. If a carpet or rug is going to be used where mildew growing conditions are present some or all of the time, then a carpet with all man-made fibers (both face and back) should be used. The possibility of mildew growing on this type of carpet is very small, and, even if it does, it will not damage the carpet.
The damage mildew can produce is twofold. The root system can remove as much as 90% of a natural fiber's strength in two weeks. After the mildew growth has taken place and the fibers dried out, a crackling sound can be produced if the carpet is rolled. This is commonly called "dry rot." It is not "rot" at all, but rather the damage produced by mildew in the presence of moisture. The crackling sound is the result of the crush of the hollowed backing fibers. If the mildew growth was in the backing fibers, the carpet may have little strength and can easily be pulled out or may even fall apart if an attempt is made to move the carpet. If damage this severe has taken place, then nothing can be done to correct it other than cutting out the damaged area.
Discoloration and Odor:
Mildew can also leave a discoloration inside the fibers which is almost impossible to remove. The color will vary depending upon the type of mildew from white to black, reds, browns and greens.
The presence of mildew is normally easy to detect due to the musty odor which accompanies it. Chances are the mildew will not be growing over the entire carpet, but the exact location may be difficult to determine without examining the back. However, unless the growth area is to be treated, the exact location may not be important.
If the musty mildew odor is detected, the best procedure is to stop its growth. Use a dehumidifier to remove the moisture from the air and, in turn, from the carpet. As long as the moisture is low, the mildew will not grow. Open up the windows and use fans to circulate air over the carpet. If the mildew growth is on the surface, open draperies to allow the sun to shine on the carpet.
If it is neither possible nor practical to prevent mildew growth, the carpet may have to be replaced with one made from all man-made fibers.
The construction of many buildings, with some areas below ground, produces ideal conditions for mildew growth. An unsealed concrete slab will allow moisture to pass from the ground into the room. If this is the condition under which a carpet is to be installed, three steps should be taken. First, seal the concrete. Install only a carpet with all man-made fibers, both face and back. If moisture and mildew are still a problem, use a dehumidifier. Even though the mildew may not damage the carpet, it can damage other items in the room
What About Flooding?
If flooding occurs and the back of the carpet is not made from all man-made fibers, dry the back of the carpet as quickly as possible. This may require the services of a professional carpet cleaner to take the carpet up and dry it at his plant. On smaller carpet or if only a portion of a large one is wet, one corner of the carpet may be lifted so fans can circulate air underneath. By attaching the hose to the exhaust of a vacuum cleaner, it can be inserted under the carpet and used to blow air. Caution: Care should be taken when using electrical appliances around a wet carpet to prevent electrical shocks. If the carpet is dried quickly, this should prevent mildew growth.
If mildew growth has started, then it will be mainly in the back. If the back can be examined, a discolored area may indicate the growth location.
Killing Mildew:
There are several steps which can be taken to kill the mildew once the area is determined. If it is a rug or a smaller wall-to-wall carpet that can be taken outside, so the back can be exposed to the direct rays of the sun, this will usually kill the mildew in a day or so. By giving the affected back area a light painting of a ½% solution of hydrogen peroxide (one part of fresh 3% hydrogen peroxide to 5 parts of water) and then letting the sun shine on it, it will make the action take place at a faster rate. Cleaning with a diluted carpet cleaning solution will wash the mildew from the surface, but this action alone will not kill the mildew.
These procedures usually will not remove the discoloration from inside the fibers. To do this may require very destructive bleaching which can destroy the fibers.
If the carpet is returned and used under the conditions in which the mildew originally grew, it will grow again. Not that the mildew wasn't killed but, rather, new mildew spores get on the fibers and the new mildew growth takes place.
In summary, if mildew conditions exist in your area, a carpet made from man-made materials is your best solution. If a carpet containing natural fibers is already installed in an area where the moisture is high, then a dehumidifier should be used. If the carpet is to be installed over a concrete floor, make certain the floor is sealed.
Odor DetectGreat cleaning tips and cleaning information by Lee Harris can be found at http://www.monsterjanitorial.com - Lee Harris is an expert in the cleaning industry and can answer all your questions about cleaning supplies and how to save money on these types of products.