Mysterious markings explained after appearing on pavement outside Lancashire homes

A mysterious set of markings which appeared outside several houses across East Lancashire over the weekend have been explained.

Many residents feared the suspicious pavement stains were some kind of signal. In posts on social media, several raised concerns they were used by crooks to target properties seen as easy marks.

One local, who lives in Hyndburn, told LancsLive a mysterious white mark had appeared on his front garden. The white blob, he said, confused and alerted him - especially after a conversation with a colleague living in nearby Oswaldtwistle - who had discovered something similar outside his home a few weeks prior.

After posting an image of the marking on social media, several theories were proposed - including criminal signaling. But in reality, the truth was much less sinister.


The markings are a phenomenon known as cement efflorescence. This is caused by crystalline deposit of salts that can form when water is present in or on brick, concrete, stone, stucco or other building surfaces, according to Nitterhouse Masonry.

It can appear as a powdery substance on floors and walls and has a white or grey-ish tint.

For efflorescence to occur, there needs to be water soluble salts in or on the material, moisture present to make the salt become a soluble solution and therefore, as the salt moves to the material's surface it evaporates and the salts crystallise.

It is likely this case of mysterious markings came following thunderstorms experienced across Lancashire, when bad weather struck much of the country over the weekend (Sunday, May 12).

The primary source of moisture for efflorescence are water, rain and snow - all of which may effect the degree of the phenomenon occurring. Portland cement is the must likely to effloresce compared to others due to its high alkali content.

If you find yourself dealing with this situation too, luckily there are a number of home remedies you can try to remove the markings from your property. Sometimes they can disappear on their own, but if not, pressurised water, diluted vinegar or brushing with a strong brush can all be tried to remove the markings.