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Carpet Filtration Soiling
Often a dealer will receive a call from a consumer that they sold carpet to less than a year or two ago. The caller is terribly upset because the expensive new carpet is changing from its light color to a dark color along the walls at the edge of the steps on the stairs and under some of the doors. The dealer goes out and looks at the carpet and sure enough it is getting dark around the perimeter of the room. Usually there is what looks like dark bands along some walls. Sometimes there will also be what appears as claw marks, small round dark circular areas and some larger dark circular areas. Thinking that something indeed is wrong with the carpet they will often contact a company like The Weinheimer Group certified floor covering inspectors.
At the job-site the inspector lifts the edge of the carpet along a darkened area. The edge he is lifting is tucked between the tackless strip and the wall so it is protected from exposure. When the carpet is up he observes that its edge has become anywhere from light gray to black. While the carpet is up the inspector also notes that along the dark edge either the subfloor or wall or both have gaps that allow air to pass through.
The inspector moves on to the stairs where the carpet is turning dark along the edges. Lifting the carpet at a darkened edge he observes a gap between the step and the wall.
Checking the interior doors of a room it is noted that under some of them the carpet is very dark. When the door is opened the dark area is seen as almost a perfect band.
The inspector moves on to the window areas and observes that the carpet has become dark under the floor length draperies and the dark areas oddly enough are in the same shape as the pleats. In another room the inspector notices that the carpet has turned dark under the vertical blinds that go almost directly to the floor and in this area the marks are in the shape of the blind slats.
After making the above observations, the inspector determines that what we are dealing with is filtration soiling.
What is filtration soiling?
Filtration soiling occurs when the carpet performing as a filter, absorbs oily atmospheric pollutants out of the air. Carpet fiber makes a great filter and this is an advantage for holding pollutants that can be vacuumed out but unfortunately the oily type soil holds on to the carpet fiber like a magnet.
Why does filtration soiling occur?
The air of most building’s have many atmospheric pollutants, much of these contaminants are composed of carbon and other non-soluble materials, such as smoke, cooking oils, gas fumes and dust. Some of the pollutants are created within the structure and others come from outside sources such as industry, vehicles, machinery, and natural sources. These contaminants flow over, under and through the carpet. They come up through open areas between the floor and the cell plate, under the baseboards or at the space between edge of the stairs and the wall. Contaminants in the air also pass under the draperies and doors and down walls, drapes, etc. Carpet being the great filter that it is, absorbs these oily soil contaminants and thus the fibers become dark, just as the filter in a furnace becomes dark over time if it is not regularly cleaned or replaced.
Why are small, dark round or claw -like areas sometimes seen on the carpet?
When air flows under the carpet through cracks in a concrete floor or openings in the wood floor. It escapes by passing up through the back of the carpet at the small holes that develop during installation from the sharp pins on the power stretcher or knee kicker head. These holes are not due to installation error but a necessary result of stretching the carpet. As the contaminants pass through these holes this results in the round dark spots, or sometimes claw-like areas on the surface of the pile near the perimeter of the room.
Why does filtration soiling affect light colored carpet?
In actuality it affects any color of carpet. Since filtration soil is dark it is easiest to see on a light colored carpet.
What type of structures is affected?
Filtration soiling can occur in almost any type of structure. Some of the more common occurrences are in rooms without return air vents where the air and its contaminants must escape someplace and it is often under a door. Frequent examples of these are:
- Rooms that have a HVAC supply vent but no return.
- Rooms with electric wall or ceiling heat.
- Rooms heated with wood or pellet stoves.
The well-sealed house or other structure is an example we have seen more and more of over the past several years. This increase has come about with the government mandated increased requirements as it pertains to insulation. In these well-sealed structures, the return air must come from somewhere, or a vacuum is formed by the suction of the return air resulting in the filtration of the contaminants.
Is filtration soiling a construction-related problem?
Filtration soiling does not occur with every structure. While the type of structure may play a key roll as to where it is going to occur, it would not be fair to state that it is strictly a construction-related problem. Filtration soiling is a natural condition that occurs when return air is restricted by effective insulation and an ineffective return air supply.
How do you remove filtration soil?
Filtration soil is difficult to remove and if it is very dark, the most you can generally hope for is an improvement in appearance. When dealing with this dark, oily discoloration’s you are challenged with a blend of many pollutants, of varying particle sizes.
Cleaning of filtration marks is not a one step process. The cleaning will require a solvent to attack the oily substance, detergent to attack soil, a lot of agitation, plenty of dwell time for the chemicals to work and a thorough very-hot water extraction. This type of cleaning is not done standing up with a cleaning wand. You will be working face to face with the carpet if you expect any type of cleaning results.
- First vacuum the area thoroughly with a crevice tool or hose cuff to remove the dry soil. The more thorough the vacuuming now the better your later results will be.
- After vacuuming, mix a high-pH pre-spray containing a built-in solvent as part of the ingredient and spray the dark area. (The pre-spray may work better if it is hot.)
- When you apply the pre-spray, do not over-wet, as you only want to wet about the top one-third of the yarn.
- Once you have sprayed the area use a tamping brush (type of spotting brush) to tamp in the solvents. The tamping will move the pre-spray further down the tuft length without over-wetting the fiber shaft along with adding needed agitation to help break the soil loose. The job of the solvent in the pre-spray is to dissolve and oxidizes the oily soil that it encapsulates.
- With carpet shampoo, scrub the area and wait about twenty minutes (dwell time) before proceeding.
- Thoroughly extract the area with very hot water. Extract thoroughly to reduce the amount of wicking (soil moving back to the surface as wet seeks dry). After all of this the area will likely still be discolored but look much better.
How do I prevent filtration soiling?
Cleaning the filtration soiling will help only temporarily if something is not done to prevent it from happening again. An alternate source of fresh air for the return air must be
Found. While some experts claim that one way to prevent or reduce filtration soiling is to remove part of the insulation or weather stripping, I do not consider this a practical solution. Another way to prevent or reduce filtration soiling is to leave a window cracked so that return air will be drawn through the window instead of from under the base plate or through the wall. Since every structure is different, it is recommended that a heating and air-conditioning expert be contacted for their recommendation.
For further information regarding filtration soil or other floor-covering problem, please feel free to contact either Terry or Kevin Weinheimer at “The Weinheimer Group LLC“.
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