Why do I have black lines along my walls?

Why do I have black lines along my walls? This is a common question for us as carpet cleaners. Unless you have kids that like to play with black Sharpies along the walls, these black lines are most likely filtration lines. We often find filtration lines in the corners of stairs, especially on the riser portion (the part that go up), along hallways, and along exterior walls. Sometimes we find them underneath doorways, especially if the doors are kept closed, and even underneath drapes, curtains, and sometimes furniture.

Why do I have black lines along my walls?
Filtration lines often form around the base of walls and in the corners of stairs

These lines can be ugly, and can be pretty hard to clean. We call them filtration lines because the carpet is literally acting like a filter- scrubbing dirt, oils, and other particulates out of the air. It is a symptom of a bigger problem- dirty air. They are found along areas of your house where air pressure is higher on one side than on the other. Imagine your house is like a giant weather system, with high and low pressure zones. The high pressure zones will push into the lower pressure zones, and will choose the easiest path to get there. If we leave our room doors open, the door is the easiest path, and air will move freely through that door. These pressure differentials are why doors will slam shut when the HVAC fan kicks on- air pressure changes cause air to move through the house. If the door is kept closed, the air will most likely travel under the door.

Air contains more than just oxygen and carbon dioxide- just look out over Boise the next time you're in Meridian or Nampa, especially during on inversion. There is a haze that hangs over the city. Outside air will have dust, pollen, air pollution, and everything else kicked up into the air. These same pollutants, plus a whole lot of others, can be found inside your home as well. In fact, the EPA has stated that Indoor Air Quality is one of it's top concerns for health. Indoor Air can actually be MORE polluted than exterior air, containing everything from oils (from cooking, candles, air fresheners), toxic chemicals such as lead (air fresheners), skin, hair, feces (especially insect and mite feces), pollen, and dirt. This becomes a problem not just for asthma and allergy sufferers, but for people trying to keep their home looking at its best as well.

As air moves around the house, it is sometimes forced under or through hollow parts of walls, trying to get to those low pressure zones. The dust and oils in the airs are filtered by the carpet as air tries to move, creating black lines along the walls. This is especially present on stairs- there is usually a closet or empty space under the stairs, allowing a big vacuum.

These black lines can become permanent stains- oils can break down and stain the plastic in the fibers, and dirt can become permanently attached to the fibers. If a normal clean doesn't make the carpet look great again, a stain removal process may be necessary. This will include more work- it may take a bit of scrubbing, along with some mild solvents to break up the oils to release the dirt. Even with the extra treatments, some discoloration may occur.

How can we prevent these lines? There are four things that really help to prevent these types of stains from happening. Having a good air filter in your HVAC system is the first line of defense- and changing it regularly. Even if your filter says it is good for 3 months, changing your filter monthly is a great habit to be in. You can even purchase a fantastic washable filter from our Online Store, but this too, should be washed out monthly.

Having your air ducts professionally cleaned every three to 5 years is also a must- not just for the life of your air conditioning system, but also for your health and indoor air quality (IAQ).

Vacuuming regularly is super important for your carpet and IAQ, as it helps to get dust and other allergens out of the carpet. Make sure that when you are doing your vacuuming you get right up along the baseboards, and even use the hose attachments that let you get right into the corners. This will help to prevent that dust build up, and keep those lines form becoming really visible. I've personally seen the lines get up to 4 inches wide, because regular vacuuming was not done in the home.

Professional hot water extraction carpet cleaning is also super important, as we are able to get the oils out of the carpet. The oils in the air are sticky, and when they get filtered into the carpet, dust and other pollutants stick to the oils. Getting the carpets professionally cleaned will get those oils out, so the carpet isn't sticky anymore. And part of getting the carpets cleaned is re-applying a premium fiber protector to the carpets, making vacuuming more efficient. Dirt doesn't stick as easily to protected carpet, and carpets will stay cleaner.

At Zerorez®, we are committed to helping you stay healthy and your home looking fantastic. Give us a call if you have any questions or need help getting your home looking its best!


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