Horizon Carpet, Upholstery, Tile & Grout Cleaners, Inc.

Ever Wonder What Those Black Ugly Lines Around Your Carpet Are?

Filtration Lines

"Filtration Lines" are soiled areas of carpet (or fabrics) created by high volumes of atmospheric pollutants (air) passing through or over the carpet surface yarns, depositing the soil in the carpet. The face yarns function just like a filter trapping dust, soil, and oily matter in the yarns. Examples include dark lines in areas that are subject to strong air passage, such as

• around the edges of a room,
• under closet doors,
• at the seams of flooring,
• at the corners and edges of stairways,
• around air registers.

What causes the filtration lines?

In our area the main cause is poor fit and finish between the walls, the baseboard, and the gully of the carpet. Air is always passing from one cavity (room, space between walls) to another. Depending on the temperature and relative humidity of the air, that air may move faster or slower. Installing a forced air heating system into the equation aggravates the process. It is like adding a big vacuum cleaner to a home. When the heating or air conditioner system starts, it creates a flow of air from every part of the home into the air conditioner. Air, like water, will rush through any opening it can find to get back to the air conditioning system. When air rushes through a tight spot like under a door, through the crevices in windows or through louvered doors, it speeds up as it goes through the small opening and slows down as it comes out into a larger opening. As the air slows down it can no longer hold some of the soil it carries. This process, occurring in the presence of a porous substance like carpet, which is designed to hold large amounts of soil, creates filtration lines.

What can you do about filtration lines?

Many carpet cleaners will tell you that nothing can be done about filtration lines. We have developed a process that successfully removes 95% of filtration lines. We use a specific concentration of one of our heavy duty cleaners, work it in by hand, and rinse it out completely. It is important to rinse the cleaner out of the carpet completely, because if any residue is left, it will attract the soil even faster than before. Extremely heavy filtration lines require two or three treatments to remove most of soil. Removal of filtration soil is priced by the foot and is a very labor intensive process. White carpets with extreme filtration soiling may not come 100% clean, but will improve substantially.

Will filtration lines come back? Because filtration soiling is a result of soil being filtered out of a strong airflow, and not a one-time stain, the lines will reappear over time. If your air ducts have never been cleaned, or not been cleaned for several years, getting them thoroughly cleaned should help slow the rate of resoiling. Usually a good caulking job on the gap between the walls and the floor will help alleviate the problem permanently.