The Black Lines Around Your Carpet Edges (And Why They Aren't Just Dirt)

You've probably seen them. Dark grey or black lines running along the edges of your carpet, following the skirting boards perfectly. They appear under doors, around the perimeter of rooms, and sometimes along the edges of stairs.

Most people assume it's just dirt. And in a way, they're right. Filtration marks are dirt — but it's a very specific type of soil deposited in a very specific way.

### What Are Filtration Marks?

Carpet filtration soiling — dark draught or filtration marks around the carpet edges — happens because your carpet is doing something remarkable: it's acting as a filter for the air in your home.

Air is constantly moving through your house. It travels under doors, through gaps between the skirting board and the floor, and through tiny openings you'd never notice. As that air passes through your carpet fibres, the carpet traps the particles it's carrying.

Over time, those trapped particles build up into the dark lines you see along the edges.

### Where Do They Come From?

Filtration marks are produced by the air moving through your home and the contaminants it carries. Outside, this includes car exhaust fumes, combustion particles, and industrial emissions. Indoors, everyday sources like candles, cooking, and open fires add to the mix. These fine particles are drawn through gaps and openings, and your carpet acts as the filter that catches them.

This is why filtration marks aren't a sign of poor housekeeping. They happen in clean homes. They happen in brand-new homes that have never been lived in. They're a result of air movement and airborne pollution, not how often you vacuum.

### Why They Appear in Certain Places

Filtration marks follow the paths where air moves most. That's why you'll see them:

- Along skirting boards where air escapes through gaps
- Under closed doors where air passes through the gap
- Around the perimeter of rooms
- Along the edges of stairs

### Can Filtration Marks Be Removed?

In most cases, these marks can be significantly reduced or removed entirely. We spray the affected areas with a specialist chemical and work it in with a drill brush.

If you've spotted these marks in your home, get in touch and we'll take a look.

Our professional carpet cleaning service can remove filtration marks and restore the appearance of your carpet edges.

Book your free quote today. We cover Burton, Derby, Swadlincote and all surrounding areas.