What causes those mysterious dark lines?
You may have noticed it in your own home – dark, dirty-looking lines in the carpet around the baseboards, under doors and on stairs. These lines have absolutely nothing to do with housekeeping, they’re not a carpet defect, nor are they caused by mold.
They are called filtration soiling.
Filtration soiling is most common in homes which have forced air HVAC systems. At certain locations in the carpet, air is being forced through the fibers by pressure and temperature differentials. The carpet fibers trap pollutants in the air. Some of these pollutants can come from tobacco smoke, natural gas, or oil furnaces. When combined with oily residues from cooking and other sources, the pollutants adhere to the carpet. The particles themselves are small and difficult to remove. The best way to combat these dark lines is by preventing them.
How to Prevent Dark Lines on Carpet Edges
Make sure that your gas or oil heating systems, cooking appliances, and water heaters are operating properly.
Have heat exchangers, flues, and chimneys checked by an HVAC professional for leaks or improper function.
Limit how often you use the heavily scented candles.
Install high quality air filters in your heating and air system. This may require modifications to the system. Check with a qualified HVAC contractor.
Consider using air purifiers, especially if smokers are present in the home.
When using a fireplace or wood stove, ensure there is adequate fresh air entry so as to create enough of an updraft for the fireplace. You may need to open a window a little. Do not turn on ceiling fans in areas where you have a fireplace burning. Air currents may pull smoke into the living space.