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How-to Guides

How to clean natural stone patios

A dirty natural stone patio in need of a good clean!

A helpful guide to cleaning common natural stone patios

If you wish to clean a natural stone patio Floorseal has several products which are suitable.

When cleaning patios, the problems encountered are usually organic contaminations, but can also be installation faults left on newly laid pavers, such as cement staining or hazing.

Different types of natural stone can have problems which are particular to them. Sandstones suffer from black spot lichens to a greater degree than limestone. We have also included some artificial surfaces within this article as the method for cleaning is often the same.

The main products featured in this article are:-

Floorseal Patio Cleaner Plus – A deep cleaning solution for removing all organic contaminations. You do not need to use a pressure washer in conjunction with this patio cleaning product.

Floorseal Black Spot Remover Plus – Removes the most stubborn black spot lichens and all other organic contaminations. You do not need to use a pressure washer in conjunction with this product, but it is beneficial to do so.

Cleaning older or existing patios, pavers & slabs

The contaminations you are likely to see on older slabs will vary depending on the surface type. Sandstone & concrete will suffer from general organic contaminations such as black spot lichen and green algae.

Block pavers & cement-based tiles also suffer from black spot lichens and can be treated in the same way as a natural stone patio.

Pale limestones tend to have ingrained dirt & grime which is obvious on the surface. Limestone can also suffer from black spot lichens as does travertine.

All surfaces suffer from dirt, grime, algae, lichen and possibly oil and/or rust contaminations.

Outdoor natural stone patio with grey pavers

How to deep clean patios, pavers & slabs

Floorseal Patio Cleaner Plus will remove all organic contaminations including black spot lichen. Patio Cleaner Plus will also remove algae, slimes, fungi, and leaf staining.

Dampen the surface with a hosepipe before applying Patio Cleaner Plus. Dilute the solution 1:1 with clean water & apply with a simple garden pump-up sprayer (we recommend this pump sprayer), alternatively apply the product with a watering can.

Leave to dwell and do not allow the solution to dry out during the dwell time. Use a dwell time of 15 mins to 1 hour, possibly more on really dirty patios – please adjust the dwell time to suit your patio’s condition.

To keep the surface wet apply more product or very lightly mist with water. Using more product as a wetting agent is preferable as you do not lose the strength of the product by over diluting it. Rinse the product away with clean water from a hosepipe after the dwell time.

Apply to sandstone, slate, limestone, granite, concrete & clay-based pavers, bricks & other porous surfaces. This product is also suitable for deep cleaning outdoor porcelain tiles.

You can pressure wash the surface after rinsing but just rinsing away the product with a hosepipe is usually adequate.
It is certainly possible to clean your patio with this product without using a pressure washer to start or finish the process. Particularly if your patio is just having a spring freshen up or only has contaminations of green algae or general speckles of black spot lichen.

5 Litres will cover up to 40m2 when diluted 1:1 with water.

typical back spot infestations on natural stone patio areas

Removing the most severe black spot lichen from your natural stone patio

If severe black spot is present, we would recommend using our stronger product – Floorseal Black Spot Remover Plus. This product will remove very severe black spot and all other organic contaminations.

Black Spot Remover Plus is our strongest exterior cleaning solution that can be used on natural stone like sandstone, limestone, and slate. It is also safe for use on concrete precast tiles and clay-based block pavers.

Use a long dwell time to remove all the lichens. For the worst contaminations expect to spend 1-4 hours removing all the lichens.

Pre-wet the surface with water, apply the product neat and keep the product wet during treatment. This is best carried out with more product, but some water can be applied as a mist from a hosepipe or sprayer.

Agitate periodically and rinse heavily after use. For best results pressure wash the surface before and after using the cleaning fluid. It is possible to just use the product and agitate with a brush, rinsing the product away with a hosepipe. It will depend on the level of contamination to your patio.

Apply to sandstone, slate, limestone, granite, concrete & clay-based pavers, bricks & other porous surfaces.

We recommend carrying out a test patch, this provides a dwell time required on your patio.

Work in sections on larger patios, it is easier than attempting to clean an entire patio at once. Patience is the key to fully removing heavy contaminations of black spot lichen!

5 Litres covers approximately 20m2 when applied neat.

cleaning natural stone patios with rust marks

Removing rust marks from patios and pavers

To remove rust stains from patios and paving slabs use Floorseal Rust Remover for Stone.

Rust spots are often left by the feet of metal patio furniture or plant holders. They can also be from the overspray of lawn or plant fertilisers.

To remove rust spots carefully scape away any obvious lumps from the surface. Then apply Rust Remover for Stone to dry stone. Keep the surface of the material being treated wet with the product during use.

Do not allow the product to dry out, always remove the solution after no more than 10 minutes. Agitate with a stiff brush and rinse heavily after use. The product turns a deep purple colour as it reacts with the rust. Repeat the process for heavy contaminations.

Apply to sandstone, slate, limestone, granite, concrete & clay-based pavers, bricks & other porous surfaces.

Removing cement staining from patios, pavers, and slabs

If your slabs are contaminated with cement residues this can be removed with Floorseal Cement & Grout Haze Remover. Suitable for use on sandstone, slate, and other acid-resistant surfaces.

This product can be applied diluted from 1:5 with clean water, to being applied neat. Rinse heavily after use and avoid contact with metals.

*Do not use on acid sensitive surfaces like limestone or concrete tiles. Always test in an inconspicuous place before using this product.

Efflorescence on natural stone paving can be removed with a specialist cleaner

Removing efflorescence from natural stone patios

Efflorescence is just a salt left on the surface of the stone. This occurs when moisture has passed through the material and evaporated from the surface. It can easily be removed by applying Efflorescence Remover.

Efflorescence can run its course over a period of weeks or months, obviously, you may never see it all. In the first instance, it can be brushed off the surface, then any difficult deposits can be removed with Efflorescence Remover. The surface can be treated periodically with this product if the salting only appears occasionally.

Please note on newly laid patios, efflorescence can continually appear over the first few months, then disappear and never return.

Over time if there are obvious marks & crusts developing, use Efflorescence Remover. Crusts will usually only form when there has been a great deal of moisture transfer. If this is the case, you may need to scape any obvious deposits away and then treat with the remover.

*Only use Efflorescence Remover on acid resistant surfaces, such as sandstones and slate. Do not apply to limestones, travertine, and concrete etc. Always test in an inconspicuous place before using this product.

What is the best way to clean your natural stone patio?

In summary, there is a solution and product for any cleaning problem:

Patio Cleaner Plus is a strong solution for deep cleaning your patio. This solution will remove green algae, slime, fungi & black spot lichens. Can be applied to any surface which requires deep cleaning. You do not need to use a pressure washer in conjunction with this product. 40m2 of coverage per 5 litre container.

Black Spot Remover Plus is our most powerful patio cleaner. This cleaning fluid will remove severe black & white spot lichens as well as all other organic contaminations. Can be applied to any surface which is really suffering from black spot lichen. For best results use a pressure washer before and after use. 20m2 of coverage per 5 litre container.

Cement & Grout Haze Remover is for the removal of cement and cement-based grout hazes from acid resistant surfaces. Such as sandstone, slate, and clay-based block pavers. Do not use on acid-sensitive surfaces like limestone.

Efflorescence Remover can be applied to remove efflorescence salting to acid resistant surfaces like sandstones & slate. Do not use on acid-sensitive surfaces like limestone.

Rust Remover for Stone is a non-acidic solution for the removal of rust spots. This may be from metal furniture, plant pots or plant/lawn fertilisers. Safe to use on most natural stone but always test first.

Green Remover Concentrate can just be applied as a general cleaner for moss & algae. Once your patio has been intensively cleaned with Patio Cleaner Plus or Black Spot Remover Plus; an overspray with this product (once or twice per year) will keep it in tip-top condition. Green Remover Concentrate acts as a preventative measure inhibiting the return of organic contaminations if applied annually.


Further information

Please Click Here to view our products & accessories for cleaning and sealing natural stone patios. This includes all our handy ‘how to’ guides for cleaning and sealing natural stone patios.

The information contained within this article is not exhaustive. If you need further information please contact Floorseal on (01484) 861461 or email us our web address is