Along the lines of floorboards under carpet only in extreme cases.
Dirt around edge of carpet.
According to procare the premium carpet upholstery care specialists.
You may need to use detergent for more persistent stains.
Filtration soiling is pollution that comes from dirty ductwork and settles on your carpet.
Let the carpet dry then vacuum again to remove any surface dirt and loose fibers that remain.
The first step to preventing filtration soiling is to be sure that your ducts are clean.
Filtration soiling occurs when there is an imbalance in the air ventilation of the room.
The carpet acts as a filter gathering the dirt from the air.
Along the edge of walls where the carpet meets the wall.
As the air is forced through the ventilation system it picks up whatever dirt is in the ducts and carries it into the living areas of the home and thus potentially into the carpet.
This soiling is called filtration soiling because it comes from air passing through the carpet as it is attempting to get through the crack between the.
This will help release any trapped dirt dust or debris.
Along the corners of a room.
Start with the hvac system.
The black lines are a result of filtration soil.
Along the edges of carpeted stairs.
You can also use a dampened white rag to scrub your carpet edges.
To clean up these stains you need water and vigorous scrubbing.
Dark dirt marks around the edges of your carpet are caused by an issue called filtration soiling.
You can find evidence of filtration soiling anywhere airflow is restricted near carpeting.