Professional Carpet, Upholstery and Hard Floor Cleaning
What causes it?
Filtration soiling occurs as a result of air being forced into the room or space at a higher rate than it can escape from the same area.
The air then seeks alternative escape routes, which usually end up being the gap between the carpet and the wall trim and under closed doors.
As the air is forced through these gaps, it passes through the carpet, which acts as a filter to the air. Any pollutants in the air are trapped by the carpet, and turn the carpet black in that area. Common pollutants that can contribute to the problem include smoke from cigarettes and candles, cooking oils, fireplace ash, and dust.
This soiling does not occur as a result of insufficient vacuuming or improper vacuuming techniques (although consistently failing to vacuum the very edge of the room can help to amplify the problem). It is a problem that can occur in the cleanest of homes, and is not considered a reflection of house keeping abilities.
Another way to reduce the problem is to eliminate the gaps through which the air seeks to escape. As much as possible, keep interior doors between rooms open to allow the air to move freely through the opening, so that it does not travel down and into the carpet to escape under the closed door.
Gaps between the carpet and baseboard trim may be sealed using an expandable foam sealant. Depending on the size of the gap, you may need to pull the carpet away from the wall in order to access the entire area and avoid getting any of the sealant on the carpet.