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Masonry: Dirt and Discolouration

Here at Relkogroup, we have a lot of experience with stone and brick structures of every kind. Throughout the last few decades, we have had to deal with dirty, discoloured and even damaged masonry, for all sorts of reasons.
Sometimes our masonry cleaning services have been required to remedy damage caused to buildings by age, weathering and the conditions so typical of urban centres like Birmingham and London. In other cases, the damage has been caused by one-off incidents like flooding or fire.
Either way, it is our years of experience, our expertise and our ability to carry out professional remedial work to the highest standard that enables us to take on whatever projects come our way.
Of course, we also understand that half the battle is knowing what kind of damage has been done and why it has occurred in the first place, which is why we have put together the below guide to masonry dirt and discolouration. Read on for more.
Know the basics

Stone is porous in nature, which means it absorbs water and moisture in the atmosphere, but can dry out in warmer conditions.
Now, when pure, clean water is absorbed, no trace is left, other than damp patches on facades, which soon dry anyway. However, if there is a staining agent present in the liquid absorbed, this can result in the staining and discolouration of the stone.
Of course, the clean liquid itself is still a threat to masonry because of the damage it can cause with erosion, freezing and so on. And when this degradation is compounded by discolouration, the problem is even greater and in need of professional remedial services like ours.
Common issues
Dirty or Soiled Surfaces:
Dust and dirt will accumulate on an exterior surface, blown there by wind or occurring as a result of modern issues like air pollution and car fumes. Some of this dirt can be stubborn though, requiring thorough cleaning services to restore the masonry.
Mildew, Moss and Organic Matter:

Whether it is mossy patches here and there or ivy growing up the walls, unwanted organic matter is a nuisance. More importantly, it can actually cause damage and staining.
Masonry, stucco, concrete and more; all buildings are subject to discolouration as a result of compounds in the mortar, and moisture and staining agents on the surfaces, especially around the edges of bricks and stones.
Chemical compounds can also be an issue when it comes to chalking or powdering (a result of weathering), which can give the appearance of discolouration. Chalking is in fact caused by weathering and can be cleaned easily.
What causes discolouration?
 There are several reasons your masonry may become discoloured or dirty in appearance over time. The most common reasons are:

  • Liquid enters the masonry from the top surface, leaving a stain (often green-tinged)
  • Moisture is present as a result of naturally occurring minerals in the stone
  • The mortar contains staining agents that stain the stones’ edges if moisture bleeds through
  • Chemical reactions occurring in the mortar (e.g. calcium hydroxide becoming calcium carbonate, which leaves a grey discolouring
  • Oxidisation of iron compounds in the stone, which leaves yellow-brown discolouration

Whilst dirt build-up is to be expected on building exteriors, due to the many natural and urban influences like dust and smog, discolouration is a problem that needs to be identified swiftly and dealt with professionally.
As well as being a problem in terms of aesthetic appeal, discolouration can be a symptom of bigger issues. So see if you can spot any evidence of dirt build-up, grime, discolouration or damage. Then get in touch with the team here at to discuss you specific needs and viable solutions.