Do You Have Dark Lines Around the Edges of Your Carpeting?

Filtration Lines: Do You Have Dark Lines Around the Edges of Your Carpeting?

More and more often, our Citrus-O carpet cleaning technicians are finding a phenomenon that on first-glance doesn’t make any sense to our customers- dark lines of what appear to be dirt have formed all along the outer edges of the customer’s wall-to-wall carpeting and often directly under doorways that normally remain closed. This doesn’t make sense because these areas of the carpeting receive virtually no foot traffic and should logically be one of the areas of the carpeting that always remain clean. And besides being visually unappealing, normal vacuuming does not seem to reduce or remove them….. Why are they there, and where did they come from?

In the parlance of carpet cleaning, these dark lines are usually referred to as “filtration lines” and there is a logical explanation for them. It has to do with the fundamental fact that your carpet is really acting as a giant filter in your home, catching and holding all sorts of dirt, dust, crumbs, spills, dead skin cells, hair, and “you-name-it” that is part of every normal household. Most of this miscellaneous material is large enough and heavy enough to settle into the carpeting, and can be regularly removed through vacuuming, but there is also various microscopic pollutants floating around in your home’s air, such as dust, smoke, air-borne grease from cooking, soot, etc. These types of pollutants may be cycled through your furnace system and some may get caught in the better quality furnace filters, but mostly they settle onto your furniture as dust, or air movement and traffic keep them air-borne. It is this super-small, virtually invisible material that is actually responsible for the dark lines that form under doorways and along the edges of your carpeted rooms.

It all has to do with the air pressure that your central heating/cooling system creates in your home, and the fact that homes are being built more and more air-tight. When your furnace forces air into the various rooms in your home, the positive pressure will force the air to escape out of the room through any crack, crevice, or opening, like under a closed door, and over time, the carpet fibres under the door will trap those microscopic air-borne particles, eventually resulting in the darkening of the carpet fibres. Air movement in a house requires two things- a difference in air pressure and an opening. Air will move in your home to where-ever it can escape in an attempt to equalize the over-all pressure, and besides flowing under doors, this can include cracks or breaks in the sub-flooring under your carpet, especially along the edges of rooms where the sub-floor meets the wall. Unfortunately, these spaces between the sub-floor panels are often intentionally left there by the home-builder to allow for expansion and contraction of the wood. When carpeting covers over these spaces, the filtration effect comes into play, and over time, pollutants in the air darken the carpeting.

Prevention is the best way to reduce or avoid filtration lines- here are a few tips:

  • Avoid light-coloured carpets
  • Keep soot and smoke sources out of your home- especially candles, wood-burning fireplaces and stoves, and cigarette smoke
  • Install a high-efficiency filter in your furnace
  • Install a perimeter of hardwood flooring around your carpets
  • Caulk or seal all baseboards before applying trim and installing carpeting.

If you already have a problem with filtration lines, hire a company like Citrus-O Carpet Care that has special tools and cleaning solutions designed to clean these stains. If your lines are mainly due to dust and dirt, an initial cleaning should greatly reduce these lines, and they may completely disappear after a second cleaning. Unfortunately, filtration lines caused by carbon soot (from candles or wood fires, for example) are often permanent, and cleaning may only reduce their intensity. If your filtration lines are bad enough and a real distraction, a carpet repairman may be able to cut them out and then re-stretch your carpet to fit. Or a carpet dyer may be able to dye a darker, contrasting stripe around the perimeter of the carpet to hide the staining.

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