Filtration Soiling

Dark grayish lines under doors, around baseboards, and along edges of stairs are symptoms of an aggravating problem -- Filtration Soiling.

The cause of the problem is really quite simple: Dust, smog, and other airborne pollutants accumulate where concentrated airflow is directed over or through the carpet's pile. The carpet 'filters' out these pollutants and gradually becomes discolored. (See Example)

This condition may appear over a period of only weeks, or it may take months or even years to become visible. The severity of the problem will be proportional to the volume of airflow and the relative dirtiness of the air. And of course, it is most visible on lighter colored carpets, particularly off-whites. Defective Carpet? No. Filtration soiling is not an indication of low quality carpet, or of a defect in the carpet or its components. It can appear on any carpet regardless of price, style, quality, construction, or face fiber.

As described above, filtration soiling is caused by environmental pollution. It cannot be caused by anything done at the time the carpet or its fibers are made. And, while fluorochemical soil retardants may make it easier to correct, no fiber modification or topical finish can prevent filtration soiling from appearing.
Airflow? In most cases, the airflow is created by heating and air conditioning systems, thermal expansion and contraction of the air, or the natural convection currents in the home. It may also be caused by wind blowing through a home via windows which regularly remain open.
Can I correct it? Filtration soiling is usually at least partially correctable by professional cleaning. However, many of these pollutants are introducted to the fiber on a molecular level, much smaller than soil from other sources. Some of these soils, auto emissions for example, are oily in nature, and are attracted to synthetic carpet fibers. These factors can make complete removal of filtration soiling quite difficult, sometimes impossible.

The professional carpet cleaner should be aware that filtration soiling rarely responds to normal cleaning procedures. Dry solvents, such as l.l.l. tricholoreothane, mineral spirits, or citrus solvents, followed by rinsing with a mildly alkaline detergent solution, are some of the best remedies. We have many other products new on the market that can greatly enhance the problem.
What can be done to prevent it? Unfortunately, not much. But leaving inside doors open as much as possible will help prevent filtration soil lines from appearing in doorways.

Keeping the air inside the structure as clean as possible by regularly cleaning and replacing heater and air conditioner filters is another good preventative measure.

Information based on materials supplied by Fibercare Services, Chino, California.

For In-Depth 32-Page Report - [PDF] Investigation of Carpet Soiling

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