Do you have black line around the edge of your carpet?

locationJune 2015

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

This is a question we regularly get asked when visiting clients homes for a quotation, carpet cleaning in Bedfordshire or when talking to customers over the phone.


So what are theses black lines? The technical name  is “Soil Filtration Lines” also known as “Venting Marks or Draught Marks” they are dark soiled areas that gradually become more noticeable on  your carpet.

They are most commonly found around the edges of a room, beneath doors – particularly airing cupboard doors, patio doors, and around hot air floor heating vents. We also see these marks in clusters or spots around the edge of the carpets where the carpet fitters stretching tool has penetrated the back of the carpet leaving small holes in the backing, in some extreme cases you can actually see the outline of the floorboards.

The cause of these marks is simply the air moving through wall cavities, beneath the gaps between floorboards and skirting or through heating or air vents.

Black lines on customers carpet showing the shape of her furniture. This was caused by the warm air heating system in the customers home.
Black lines on customers carpet showing the shape of her furniture. This was caused by the warm air heating system in the customers home.

The air passes through the carpet and the fibres act like a filter  to hold onto the soil particles, this soiling can be greasy and may require special attention to ensure a satisfactory result, even then, they cannot always be eradicated completely. The degree of removal depends on the amount and type of soil, length of time the soil has accumulated, amount of airflow, colour of carpet and type of fibre. The lines can be removed most easily from synthetic fibres. However, in severe cases, especially on light coloured carpets, traces may still remain after cleaning.

Once we have explained the cause of these marks to our customers we often get asked,   “why should it happen, can’t anything be done to prevent it happening?”

Measures can be taken to help reduce the possibility of the dust migrating through to the carpet fibres, loose floorboards should be securely fixed, if the floorboards are particularly uneven or have large gaps they can be covered with hardboard or plywood which would be fixed to the floor.  Gaps between the floorboards and skirting boards will need to be sealed with a flexible sealant, joins in the underlay should be taped over and all edges of the underlay need to be secured by stapling.

All of these remedies would ideally need to be done at the stage of fitting new carpets and can usually be done by the carpet fitters, it should be pointed out or requested at the time of the visit for the measuring of the new carpets. However in some extreme cases, existing carpets will need to be lifted and refitted to carry this work out.

If you have any questions about the above or would like some advice on the removal of these black lines on your carpets in Bedfordshire then give us a call on 0808 144 0190 or fill in the quick and easy form below.