How to clean a slate patio?
Cleaning a slate patio is easy when you have the right products. You’ll need a patio cleaner, a pump-up sprayer, and a pressure washer.
In this guide, we’ll talk you through how to clean slate patios, how to identify if you have a slate patio or another type of natural stone, and maintenance tips to keep your slate patio looking spotless.
Within this article, we’ll also be talking you through the best Patio Cleaner to use for Slate and Natural stone surfaces, and how to maintain the finish for longer.
What is slate?
Slate is considered the finest-grained foliated metamorphic rock. It is widely used in building roofs and floors. It forms when sedimentary rocks like shale and mudstone, or volcanic ash, are compressed under intense heat or pressure deep within the earth.
Do I have a slate patio or Indian Sandstone?
It’s incredibly common for people to mistake slate patios for Indian Sandstone. Especially when dealing with grey varieties like Kandla grey sandstone.
At a glance, they can look similar but are very different. Most of the time, people discover they actually have a sandstone patio, not slate.
What’s the difference between Indian Sandstone and Slate?
Slate has low porosity and is naturally waterproof. Whereas sandstone is very porous, meaning it is more susceptible to organic growth such as black lichen spots. Slate is strong but can delaminate easily.
Indian Sandstone is more suitable for patios and paths as it's more durable; however, if constantly pressure washed, it can become susceptible to frost damage. Over the last 20 years, Indian Sandstone has become very popular due to its relatively low cost compared to York Stone that can be 4-5 times more expensive. It comes in a range of different colours and is fairly slip-resistant due to its riven nature. Sawn sandstone can be much harder to maintain and stains far more easily than riven surfaces.
The process to clean Indian Sandstone and Slate is the same
As both surfaces are natural, you’ll need the same product to clean the stone. We would recommend a patio cleaner that revives the natural colour and removes organic staining without relying on aggressive pressure washing. You’ll need a pressure washer to rinse the product off afterwards, but to prevent damaging the stone or the pointing, we’d recommend not relying on pressure to clean the stone, as this can cause short and long-term damage.
How to keep a slate patio clean?
Once you have restored the natural colour of the slate and removed all surface dirt, in 11-12 months, use a spray and leave algae remover to prevent the return of stubborn staining, maintain the integrity of the stone and remove algae. Once applied, this product will remove algae within 3-5 days without the need to pressure wash.
If purple staining occurs from berries or bird poo, simply apply a small amount of patio cleaner to the area, allow it to work for 20-30 minutes, then lightly wash off with the hose.
Why you shouldn’t seal natural sandstone
Natural stone should be left to breathe, not sealed. All natural stone sealers on the market are sold as breathable or microporous for this reason. As they still allow the stone to breathe, they allow lichen spores and algae to still penetrate the sealer. This means your patio is still likely to get black spots and algae growing and, in some cases, make it hard to clean in the future.
Will a Patio Cleaner still be effective on a sealed patio?
Yes, a Patio Cleaner will still be effective against organic growth and ingrained dirt. However, depending on how long the sealer has been in place, the cleaner may take longer to work due to it having to fight through the sealer to get into direct contact with the stone.
Slate Patio Turning Green?
In periods of wet weather, Algae will grow on slate patios and sometimes make it more slippery. Algae grows when there are damp conditions and sunlight. Algae is easy to remove with a pressure washer, a spray and leave treatment, or part of a more intense clean. There are many products on the market that claim to prevent algae from returning, but these claims are false.
What if I have more questions about my patio?
If you have more questions about how to maintain your stonework, contact Patio Black Spot Removal Company by phone on 0800 500 3032 or email support@pbsr.co.uk. Alternatively, use the online chat for quick responses to questions.
