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What Are Those Dark Lines Around the Edges of My Carpet?

Soil Filtration LinesSoil Filtration Lines Along Edges of Carpet

Soil filtration lines, also known as soil lines, smog lines, and perimeter soiling, are dark soiled areas that develop gradually on carpeting.

They are most common around the edges of a room next to the wall, under baseboards, under floor length draperies, under doors, and on edges of stairs. But they can develop anywhere there is an air space, such as between floorboards or spaces in the subflooring under the carpeting.

They can even occur under the skirting of furniture. Bedroom doors that are closed at night, especially where windows are left open, are likely to develop the lines as well.

Soil Filtration Lines Under DoorSoil Filtration Lines Under Door

Why Do Soil Filtration Lines Occur?

Your carpeting acts as a soil filter in your home environment. As hot air rises and peaks out at the ceiling tops, it is redirected to cooler surfaces, such as the outer walls or another room, and travels down to the carpet. As the air passes through or across the carpet, it carries microscopic particles of dirt, dust, and soot.

These soil particles settle and become embedded in the carpet pile yarns, bonding to the fiber. Because the soil is very fine, it can penetrate deeply into the yarns.

What Kinds of Soils Form Soil Filtration Lines?

Some of these soil particles can be the result of fireplace emissions, as well as from cooking oils that have become airborne and have settled into the carpet. Cigarette and cigar smoke, burning candles, and the residue from furniture polish can all contribute to the problem.

Soils that are primarily oily can form an electrical bond with the fiber and their size makes it easy for them to attach to the dye sites on a fiber that hold the color of the carpet, making removal extremely difficult or impossible. The oily soils trapped by the carpet will also attract more dry soil.

An improperly balanced ventilation system can also cause soil filtration lines. This happens when the volume of air entering a room exceeds the capacity of the system to remove the air from that room. The excess air will then seek to exit through gaps along walls and stairways.

Are These Lines Considered a
Defect of the Carpet?

These lines are not a result of a carpet defect or a carpet quality issue. They will, of course, be more obvious on lighter colored carpets. These lines can develop fairly quickly, or it can take months, even years.

This type of soiling should also not be considered a result of improper or insufficient vacuuming either. However, the problem can get worse if the edges of the room are not consistently vacuumed (even though these areas are usually the hardest to reach with a vacuum cleaner!)

Why are They So Difficult to Remove By the Homeowner or Even After a Professional Cleaning?

These lines are so difficult to remove, especially by the homeowner with do-it-yourself methods, because the extremely fine soil is composed of a combination of both water soluble and oil soluble particles. The lines that form under baseboards especially can be very difficult to reach with a vacuum.

It might be possible to remove or remediate certain types of water soluble types of soils  with over the counter cleaner agents or aggressive vacuuming. Unfortunately, oily soil particles, especially, can bond tightly to the carpet fibers and any type of over the counter cleaner used to remove oily residues can potentially harm the carpet itself by delaminating or loosening the backing, causing the fibers to eventually fall out.

At ABC, we use special techniques to remove (if possible) and improve the appearance of soil filtration lines. Unfortunately, the discoloration cannot always be removed completely.

The degree of removal depends on the amount and type of soil, length of time the soil has accumulated, amount of air flow, the color of the carpet, and the type of fiber. The lines can be removed from most synthetic fibers. However, in severe cases, especially on light colored carpets, traces may remain after cleaning.

It is usually very difficult or impossible to remove soil filtration lines completely from wool or olefin carpets.

TIPS to Help Prevent Soil Filtration Lines From Forming...

  1. If you own a forced hot air heating system, install high-efficiency air filters and change them periodically.
  2. Have your heating, ventilation, and/or air conditioning ducts cleaned to reduce the circulation throughout the air of small particulate matter.
  3. Keep the doors between rooms open (if possible) so the air can move freely through to the rooms, preventing it from going down and into the carpet to avoid the closed door.
  4. A few life style changes, such as not smoking inside and reducing the burning of candles, will help with managing soil filtration lines.
  5. Always use the stove hood vent fan when cooking.
  6. Dust thoroughly and vacuum frequently to keep the soiling and dust under control.
  7. Edging rooms with a crevice tool attachment on your vacuum will have the most impact on preventing a buildup.

How ABC Can Help

As always, if you have any further questions, please feel free to call or text our office at 607-272-1566. You may also contact us here.

If the soil filtration lines have been successfully removed from your carpets, an application of our Soil and Stain Protector can help you to keep the lines from returning as long as you follow the tips above.

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