Transforming Your Surfaces Through Pressure Cleaning & Black Spot Removal 

If you’re looking to spruce up your outdoor surfaces, pressure cleaning and black spot removal are two of the most effective methods for removing built-up dirt and grime. Pressure cleaning can restore the original beauty of a variety of surfaces, including decks, patios, driveways and more. It is an ideal way to remove dirt and debris that has built up over time, as well as mould and mildew. If your patio has developed black marks which you are struggling to remove, the probability is that your patio is suffering from Black Spot. Homeowners are shocked when they see their surfaces after our pressure washing and cleaning gardening services. 

How Do Patios & Pathways Accumulate Dirt? What is Black Spot?

Black Spot is a lichen which thrives on stone surfaces in the damp and shady conditions that are so common in the UK. The characteristics of the lichen are that as it matures, it sends out tendrils (hyphae) into the pores of the stone seeking nutrients from the minerals in the stone and the detritus that collects on the patio. These gradually spread through the surface of the affected stone like fine roots. The hyphae are an anchoring system for the black spot visible on the surface of the stone. This in part is what makes this problem so difficult to remove, as many cleaners only deal with the surface issue. To effectively remove black spots in the long-term, the hyphae have to be destroyed, which in turn will enable the surface black spots to be removed by manual brushing or power washing after treatment.

Black Spot is a bigger problem on stones that have larger pores as part of its structure because they offer the ideal surface for the hyphae to spread. Therefore, Black Spot does not generally occur on Indian limestone because the structure of the stone is very close grained and there is no opportunity for detritus to collect on the surface. Typical Indian limestones that would be in this group are Kota Brown, Kota Blue, Black Limestone & Tundra Limestone. Conversely, sandstone has a much more open texture with larger pores and is therefore much more likely to be affected by Black Spot.

However, there is a hierarchy within the Indian sandstones, whereby some colours are more affected than others. For instance, the better-quality Raj Green is one of the densest, close textured sandstones available, and therefore, because of its structure, will not be affected.

However, as you move through the colour range of the Indian Sandstones from dark to light, the occurrence of Black Spot becomes more prevalent:

• Black Sandstone – Slightly Affected

• Kandla Grey

• Modak

• Mellow Yellow

• Fossil Mint – Highly Affected

Fossil Mint, one of the most popular Indian sandstones, has the lightest colour and the largest pores, so it is the stone surface that is going to have the worst incidence of Black Spot, particularly if the stone is laid in damp, shady conditions with lots of surrounding plant growth.

How To Remove The Build Up

During the first 2 years after a stone surface has been laid, any Black Spot growth will appear to be simply a surface problem that can be successfully removed by power washing. However, this is not removing or killing the spreading hyphae that are within the stone surface. Over an extended period, the hyphae, now well-established within the stone surface, creates an anchor for the black spot to colonise the stone surface which will become increasingly blackened, and more difficult to clean away.

The use of a high temperature, low pressure steam cleaner (such as Doff) will kill the black spot but won’t always remove the more stubborn black marks on the stone unfortunately (dead but not removed!).

A far more effective way of killing and removing black spot, is to use specially designed and formulated products, which have been developed by scientists after researching the best way to kill the lichen to prevent new growth, and also remove the existing marks.

The best products are biocides which will get into the growth and kill the Black Spot permanently, but also have a bleaching agent which will bleach the blackness out of the visible Black Spot.

To work properly it is necessary to ensure that these products remain on the affected stone for at least an hour (but up to 24 hours) and that during the treatment period the stone surface remains wet.

After treatment the biocides will have killed all the Black Spot spores, preventing new growth from occurring in the future. Most of the remaining dead black spot deposits will not be visible as the chlorine content will have bleached them. Sometimes, particularly stubborn deposits will remain on the stone after treatment.

Rest assured, that over time, now that there is no live lichen in the stone, these (bleached) dead deposits will loosen, and the next time the patio is power washed, any remaining lichen deposits will be removed, and the stone surface will become as clean and brilliant as it was when first laid.

How BZ Gardens Could Help You

Our property maintenance services can assist homeowners and landlords with a range of outdoor tasks that can be difficult and strenuous without prior experience or ideal machinery. Our experts are able to arrive on site and pressure wash your pathways, driveways, patios and more removing dirt and debris as well as black spots. We pride ourselves on the quality of our service, our reliability and our safety. 

BZ Gardens – Our Hard Landscape & Gardening Service

If your patios or pathways are looking neglected and dirty, you may be in need of effective cleaning. Our hard landscape and gardening service experts are able to arrive on-site and completely transform your outdoor surfaces and hard landscape features. For more information get in contact with us here. We’d be more than happy to help!