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What are black spots?

Black spots affecting paving surfaces are becoming an ever-increasing problem within the UK and that’s because the UK is such a damp environment, which black spots (Lichens) love.

The reason black spots have worsened on patio surfaces throughout the UK over the last 30 years, is due to the lack of industrial factories being used. During the 1980s, the UK had many Industrial factories, which contributed to air pollution and therefore created Acidic rain, which would then go on to stop bacteria forming, keeping the black spots away.

Black spots know as Lichens, are formed of two bacteria’s, Fungi and Algae and we are all too aware of just how stubborn they can be, especially when feeding from our paving surfaces, as they spread all across the patio. Black spots (Lichens) create a biofilm surface protection layer once formed, which stops us being able to remove them from the patio surface, unless killed with steam or chemical application.

Which paving surfaces are prone to infection?

Black spots (Lichens) will grow on any porous surface with the right conditions but sedimentary stone being the first choice, as it’s very easy to penetrate i.e., Indian Sandstone, Yorkshire stone and Sandstone. Limestone, granite and porcelain patios are less infected for various reasons.

Wet-cast concrete block paving is susceptible to Lichens growth, as they hold a low cement content, meaning the Lichens can feed from them more easily. Pressed block pavers are cement rich, so lichens are less likely to form on these surfaces, but it’s not impossible! Clay pavers are less likely.

Unsealed Imprinted concrete can form lichens in damp conditions but they will develop slowly and over a period of time as the material is cement rich.

Removing black spots

Firstly, safest and most effective method for removing black spots, is steam cleaning at low pressure. Steam cleaning will kill and remove living organisms on most surfaces. Steam cleaning is safe for the environment and to the wildlife. Please check the compatibility of steam cleaning with your patio surface first.

Secondly, a government approved biocide treatment and pressure clean will remove black spots. We recommend using Smartseal Patio Extreme Cleaner or Benz Lightening Cleanze, both products we have had successful experiences with. When using these products, please check the compatibility of the product to the surface. Please read the label carefully and follow the instructions.

Thirdly, calling in an experienced contractor with the correct knowledge, know-how and equipment to complete the safe removal of black spots from the patio surface, is an option.

Please call 01582 757304 if you would like more help and advice or if you are seeking a trained contractor.