'I recommend using a specially-formulated black spot remover, such as Rob Parker's Best Patio Cleaner,' says Ivo Iv, Founder, Decor Home Ideas. 'This product can be used on all types of stone surfaces and will not only kill the black spot permanently but also bleach the blackness out of the visible black spot.
If you have greenish-black stuff on your concrete patio, it's probably mold, mildew, or moss. Damp or moist conditions from rain or humidity can encourage mold and mildew to grow in those nooks and cracks of concrete pavers or bricks.
Wash patio slabs with white vinegar
This eco-friendly solution is made up of equal parts vinegar and water, which is then left to soak into the patio to correct any discolouration and also remove tough marks.
Sanding and chiselling will leave unsightly marks on your paving, bleaching can work well but you have to be careful not to kill your plants and dilute your bleach to the correct level, some people recommend using this method only in the winter months to avoid damage to plants but you still need to be really careful ...
Combine 1 teaspoon of hydrogen peroxide and 1 teaspoon of milk in a glass bowl. Dip cotton pad or Q-tip in the bowl and apply to dark spots. Leave on for 15 minutes. Rinse with lukewarm water and finish off with your favorite serum and moisturizer.
Blackening of the surface is common when the concrete is “burned by late and vigorous troweling”. The more the troweling effort, the more compacted and dense the concrete surface becomes. The result is a reduction in the moisture content (water cement ratio) at the surface.
'I recommend using a specially-formulated black spot remover, such as Rob Parker's Best Patio Cleaner,' says Ivo Iv, Founder, Decor Home Ideas. 'This product can be used on all types of stone surfaces and will not only kill the black spot permanently but also bleach the blackness out of the visible black spot. '
If your concrete has ugly charcoal-gray or black streaks or splotches, black algae is probably the culprit. Black algae can grow on many outdoor surfaces such as concrete or roof shingles and will thrive as long as there is moisture and sunlight.
Remove those ugly green and black mold stains on your deck with Wet & Forget Xtreme Reach™ Hose End. Spray your wood or composite deck with Wet & Forget no-rinse cleaner. Allow the surface to dry (4-5 hours). Let Mother Nature do the rest of the work for you!
To clean smaller surfaces areas, pH-neutral soap, a little water, and a brush are suitable. If you want to clean larger areas of natural stone efficiently, you can reach for the electric patio cleaner or work with the pressure washer and a surface cleaner.
Simply put, black stains on flagstones are caused by certain types of mold and mildew. These fungi find their way onto the stones either from their spores landing on the stones or from simply extending onto the stones from patches of mold or mildew right beside them—a pretty common occurrence for garden pavers.
Cleaning a patio with bleach is easy.
Whether your patio is sealed concrete or cement, or even sealed concrete pavers, a bleach and water solution makes it easy to clean away built up soil, stains from leaves and pollen, mold, mildew and algae.
White vinegar is good for cleaning pavers, though it's also acidic enough to erode the stones' surface. Diluted vinegar can be used safely to clean paving stones, though it should be used sparingly and infrequently to protect your paving from damage.
And, while it may be tempting to use household bleach for a quick clean, Beril says that this can ruin the patio stones and leave them looking patchy. 'There are many specialist patio cleaning products on the market including brick acid,' she cautions.
Use a mild grease-cutting detergent such as Dawn or Ajax dishwashing liquid mixed with water and a natural or synthetic bristle scrub brush to help brighten the patio surface. NOTE: Never use a wire brush as it can leave rust stains and scratch the concrete surface.
Concrete paint is a remarkably effective way of making tired concrete patios look as good as new. These come in a range of colours and can make cleaning and maintenance much easier. To apply concrete paint make sure your patio has been cleaned thoroughly as described in the previous section.
Use a Pressure Washer
If you have a small amount of mold or algae, you may find that the first two steps of drying out and sweeping the area is enough to remove it. If this is not the case, pressure washing is often quite effective in removing mold and algae from pavers, bricks or concrete.
If you have dark streaks on your roof, siding, and other outside areas around your home, they likely caused by a type of black algae called gloeocapsa magma. Gloeocapsa magma is a type of cyanobacterium that can survive cold temperatures, wind and harsh sun. This is because of its dark pigment and tough outer capsule.
Vinegar and Baking Soda
Simply fill a spray bottle with equal parts water and vinegar (or water and baking soda), and add a little bit of liquid dish detergent. Spray the mixture on your concrete surface and let it sit for about 30 minutes. Then scrub and rinse your concrete.
Absolutely, you can use Wet & Forget on any outside surface, including: Concrete Driveways and Walkways, Patios, Pool Surrounds, Asphalt Driveways, Fiberglass, Brick, Painted Textured Surfaces, Tombstones, Natural Stone, Ceramic Pots, Wood Decks, Composite Decks, AstroTurf, Tennis Courts, Canvas Awnings, Greenhouses, ...