We would recommend using Black Spot Remover Plus to remove black spot from sandstone patios. It is a concentrated cleaning solution specifically developed for the removal of black spot lichen.
To properly remove black spots from a patio requires both pressure washing and softwashing. Softwashing is a method of cleaning patios and stonework with chemicals and biocides at low pressure. These chemicals sink into the stone and kill the black spots at their roots without damaging the surface of the stone.
Bleach can remove black spots from patio, but it's a harsh chemical that will potentially damage some paving materials. It's also not good for the environment, and something you should avoid using if you've got plants near your patio area.
If bleach is attempted to remove the Lichen, it will cause more harm than good. This could potentially strip the colour of your Indian sandstone, and not even remove the lichen. Lichen needs to be scrubbed off with a brush, or now you can use Universeal's New Clean 60 Patio Cleaner to assist you with the job.
Fill up a bucket with warm water and add some washing-up liquid, swilling it under the tap to create a frothy mixture. Pour the warm soapy water over your Indian sandstone slabs. Use a stiff bristled brush to scrub the surface of the sandstone paving.
Sandstone can naturally become dirty for three different reasons: firstly, air borne dirt builds up on the sandstone over time, which can make them appear dull and grey; secondly, algae has been known to grow on pavers when there is moisture present, which can lead to the sandstone appearing black; and thirdly, tree ...
Luckily, you don't need any of these fancy potions to clean Indian sandstone. For common grime, the simplest and safest remedy is good old soapy water (washing-up liquid does the trick), and to tackle more stubborn problems (algae, moss and lichens) use diluted bleach.
Once again, acetic acid will wreak havoc with your block paving. Porous stones like limestone and sandstone are more susceptible to damage than most, as the vinegar can seep into the stones themselves, though even sealed and non-porous stones can discolour and bleach.
For tough stains, mix baking soda and water until a paste is created. Use a hard-bristled brush to apply the paste onto the stain and scrub vigorously. Leave to work on the stain for up to 30 minutes before rinsing or hosing away. Repeat this process until the stain has been removed.
For deeper stains, baking soda is the safest alternative. Apply a paste of baking soda and water over the stain and leave it for 24 hours. Gently scrub the area and rinse it with plain water. Stains on Sandstone pavers, Travertine floor tiles, and Marble floors can easily be cleaned with a baking soda solution.
The patio black spots that grow on your garden stonework are actually spots of black lichen. The spores from the black lichen start life as tiny dust-like spores growing on the underside of leaves on trees and plants. These spores are carried, by the wind and the rain, onto your stonework in their millions.
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.
This is a common problem. It could either be mildew, or a reaction from tannin in the wood. Given that you have black residue on rocks, it may be mildew. If the rocks/stones are near the deck/pergola, it may just be stained water dripping on to them and then staining them.
Vinegar. Vinegar works wonders as a cleaning solution for many applications, but sandstone pavers are not one of them. The acidic nature can cause harsh effects that can stain, burn or etch the sandstone surface while also causing noticeable damage and breaking down the sandstone sealant.
The best sandstone cleaner and the best way to attack mould on sandstone walls is a chlorine bleach. Mix a cup of bleach water with about 3.5 litres of water and put it into a spray bottle. Concentrate the spray and then leave it for 10 or 15 minutes. Repeat the process before scrubbing it away with a scrubbing brush.
Sandstone can erode easily, and high pressure washing can seriously harm fine details or even whole facades. Softwashing is safe for sandstone and cleans deeply. Sandstone is made mostly of quartz, so it is a very durable stone, containing iron oxide, silica and calcium based deposits.
Step 1: Hose off any loose dirt and leaves. Step 2: In a watering can, mix 5 parts water with 1 part liquid pool chlorine. Step 3: Pour the watering can mix over the stone and leave it for around 10 minutes. Make sure the mix does not dry on the stone.
The best way to clean natural stone, be it granite, marble, sandstone, or slate, is water with some PH neutral soap, like the one used in dishwashers.
Cleaning Indian sandstone with bleach is undoubtedly an option – you'll need a bleach mixture that is equal parts bleach and water to dilute safely. Household bleach kills moss and algae, removes dirt and can help to get rid of stubborn stains, more than you'd expect with soapy water alone.
Salt damage is a particular source of damage to sandstone. Because salt is soluble and sandstone is porous, it can be washed into the stone by heavy rain. The salt, now inside the stone, will create internal stress and pressure on the stone and cause it to begin breaking down.
Sandstone is Susceptible to Water Damage. The beachy aesthetic of sandstone might make it seem like an excellent design decision for around the pool flooring. But the reality is sandstone is extremely porous, which means the chemicals and acid from pool water will destroy it pretty quickly.
Black Spot Remover contains some 'hypo' itself (less than 5%) but it performs better than neat 14 - 15% Hypo. It contains activators and wetting agents which stabilise and accelerate the performance, making it much safer to use and it won't crytalise when dry.
Unfortunately, like many things, if it doesn't get the care it needs, over time that paving can become worn, stained and tired looking. It's important that you take the time to clean your Sandstone Paving as and when it's required.
Some home owners will YouTube how to clean Indian sandstone and do a Google search on how to remove stains from sandstone patio. Some of our customers have used patio magic on Indian sandstone or a similar off-the-shelf chemical. This will work and kill the algae and lighting on the surface.
If you have dark areas of discolouration on the hard surfaces of your garden (patio, drive, paths etc) it could just be dirt so see if it can be removed with a scrub over. If it can't, and it looks like ink splatters, it's most likely to be black lichen, also known as black spot.