What are those black lines around the edge of my carpet?

Have you started to notice black lines forming around the edge of your carpet? Do they seem to be appearing around radiators, under doors and in particular the airing cupboard? I'm sure you've tried numerous ways of cleaning, but whatever you do, it doesn't budge?

The black lines are a result of filtration soil. It is pollution that comes from dirty ductwork and settles on your carpet.

In the cleaning and flooring trade these black lines are referred to as draught marks or filtration soil and are caused by the movement of air passing through the carpet as it is attempting to get through the crack between the carpet and the baseboard. Air contains pollution and it has the amazing ability to find a way through into your home. The main reason is that hot air rises. Even where the carpet gripper pierces through the carpet backing the air will flow through and form black dots on the surface of the carpet.

No matter how clean your home is or how much you vacuum ... it still happens.

So what can be done to stop the black marks around the edge, and sometimes even in the middle of the room?

Unfortunately, because most homes aren't 100% airtight, there is naturally a gap between the flooring and the walls, with the air moving between these gaps. The carpet, then acts like air filtration, trapping the solid particles. To try and stop the airflow, with any flooring installation the sub-floor will need to be fit for purpose. One way around this is to lift up the carpet and lay thick sheet of card, overlapping them and sticking them down with tap, and then around the edge of the seal the edge with mastic or caulk. If your sub-floor is made from pine it is better to lay sheets of plastic down and seal the edges. Once you have sealed the floor properly you will then be able to lay your carpet.

So what can be done if the marks are already there?

Once you have addressed the problem of drafts, you can then ask a professional carpet cleaning company to clean the carpets, although 100% removal cannot be guaranteed and the marks will return after time.

What Can I do myself?

Take care! As you will unlikely have the equipment to thoroughly rinse the cleaning solutions you will use out after the cleaning attempts. You can easily make it much worse.
It's like washing your hair and not rinsing the soap out. The soapy residue will just attract the dirt and pollution in the air much faster and before you know it the problem got much worse.