Black spots that appear on your patio are actually spores of black lichen that come from the trees. When it rains, they get nestled down into the pores of the stone. These black lichen spores lay dormant for 12 months. If left untreated, they start feeding off the mineral within your patio. Usually by the beginning of the third year on a brand-new patio, you have what we call ‘black spots’.
Will pressure washing or scrubbing my patio remove black spots?
Unfortunately, not. This lichen grows within the stone, not just on the surface. Attempts to remove these marks through scrubbing or pressure washing won’t work. On natural stone, you will need a specialist product to remove it. You may see a small improvement on concrete paving slabs with the pressure washer but these spots will return within a few months. Pressure washing over time makes the stone more porous, meaning the black lichen can grow quickly. The more you pressure wash, the worse the black spots become.
How to remove black spots from your patio.
For best results, you’ll want to use Patio Black Spot Remover manufactured by the Patio Black Spot Removal Company LTD. This product is specifically designed to not just remove the black spots but to completely restore the natural colour to patios of any age and make slippery surfaces instantly safe again.
How do you use Patio Black Spot Remover?
All you’ll need is a 5-7 litre pump-up garden sprayer to apply it and a pressure washer to remove it. Pour the solution into the pump-up sprayer, apply the product like a fine mist and saturate the slab. Within 10 minutes the colour will be restored to the slab. Green algae will disappear before your eyes and the black spots will start to break up. Leave the product to work for 2 hours. At the end of the 2-hour period, lightly pressure washes the area. If any spots remain, retreat to the area until all the spots have been removed. You’ll now be confident the product works and be confident to treat the remaining area, knowing how much product will be required.
How do I prevent black spots from growing on my patio?
Once you have completed the removal process, using Patio Black Spot Remover, if you do nothing, the spots will return. Therefore, it’s important to apply Patio Black Spot Preventer 11-12 months later. This is a spray and leave treatment that not only stops the spots from returning but also removes green algae within 3-5 days. This means you don’t have to rely on the pressure washer several times a year to keep your paved areas looking clean.
Can I pressure wash my paving?
Most manufacturers of concrete-based slabs or suppliers of natural stone will not recommend the use of a pressure washer. This is for two reasons. On natural stone, when you pressure wash, the vibration over time causes the stone to delaminate. This is because sandstone is sedimentary, it cures in layers and splits in layers. With concrete slabs, most of the time these are manufactured with a finish on the top to make them look more interesting like other natural stone patios. Over time, this finish will weather away.
By using the correct product that cuts through dirt for you and effortlessly removes organic growth, pressure washing doesn’t need to be aggressive. A light pressure wash is required just to wash away the surface dirt. Avoid using petrol or diesel-powered pressure washers that if used incorrectly, can ruin the stonework you once paid a fortune to lay.
Should I seal my patio?
Although the advice over the years has been to seal your patio to prevent it from getting dirty. This is not the approach we believe in. No sealer will stop your patio from getting dirty or stop other types of organic growth from growing. Natural stone should be left to breath. For this reason, many natural stone sealers are now microporous. However, this allows the black lichen spores to penetrate through the sealer meaning in a couple of years, you’ll have black spots again. Sealers can also make the stone very slippery. It’s an expensive process that provides no value in the long term. It’s only years of experience looking after hundreds of customers' patios each year that teaches you this.
