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The following guide is a useful how-to guide for cleaning slate patios, pavers, and slabs. It can also be used as a reference when cleaning slate walls, tables & fireplaces etc.
Slate is not typically sensitive to acids nor alkaline solutions so it is less problematic than other types of natural stone.
This guide should be used as a starting point before sealing your slate patio. There are some subtle differences between cleaning interior slate floors and exterior patios. These differences are covered in a separate article.
If you are attempting to remove old sealers, we advise contacting us first as it is quite challenging!
Before sealing slate pavers or tiles it is important to clean the surface. Cleaning products are often used for a specific purpose, perhaps the removal of cement, grout, or organic contaminations. You will need to select the correct cleaning agent, you may even need a combination of different products.
The product you select to clean a slate patio will vary depending on the contamination, and whether the slate is a newly laid or an older slate patio. The products noted below are all typically used on exterior slate patios, paths & pavers.
Cement & Grout Haze Remover – This product is for the removal of cement-based grouts or general cement/mortar. It will not react with the slate itself just the cement-based materials on the surface. It can also be applied to remove general salting and staining on the surface of slate. Efflorescence can appear shortly after laying or after wet weather. Please note: Cement & Grout Haze Remover will not remove resin-based exterior grouts or resin-based brush in compounds – Keep reading!
Sealer Residue Remover – This product is used to carry out a general pre-clean of exterior slates, it will attack the thin film of resin that may have been left when using resin-based grouts or brush in compounds. Sealer Residue Remover can also be used to remove excess impregnating sealers and certain water-based acrylic topcoat sealers. Sealer Residue Remover is typically used on newly laid slate patios.
Patio Cleaner Plus – Floorseal Patio Cleaner Plus is a fantastic cleaning product which is typically used to clean older slate patios of organic contaminations. Patio Cleaner Plus will remove mild black spot lichen, algae, slimes, fungi, and bird droppings. This product is a versatile cleaning agent which is diluted at 1:1 with clean water (apply with a pump sprayer). It can also be used undiluted on severe organic staining as well as dirt and grime.
When cleaning a new slate patio, we recommend using Sealer Residue Remover to clean the surface and to remove the invisible resin slick which causes ‘rainbowing’ which can be present around the joints. Many patios are jointed with brush-in style resin compounds, Sealer Residue Remover is the obvious choice to pre-clean newly laid slate with. Please note 2-part resins or severe/obvious resin staining will not be possible to remove via a cleaning fluid. This product is for general pre-cleaning and to break down oils left on the surface after applying a resin-based brush in compound to the joints.
Cement & Grout Haze Remover can be used on either new or older patios. Please note this product is designed for the removal cement-based grouts and cement/mortar staining from traditional mortars or grouts.
It is beneficial to slightly pre-wet the surface of your slate patio before using a cleaning agent. We always recommend heavily rinsing the surface off afterwards to ensure all cleaning products are fully removed before any further work is carried out.
To pre-clean an older patio we recommend Patio Cleaner Plus to remove dirt, grime, lichens, algae, and other organic contaminants.
It is unlikely you will need other cleaning agents unless you have been replacing old jointing materials with new.
After cleaning with Patio Cleaner Plus lots of rinsing off will be required – and possibly a little pressure washing.
If you need to strip old sealers, please contact us this can be quite involved. It is often difficult to identify old sealers unless you have a container left over. There are ways of identifying old sealers, but it is beyond the scope of this article.
Efflorescence is just a powdery residue left on the surface as moisture evaporates which leaves a salt behind. It can be washed away with water, but stubborn marks may require a cleaner.
Efflorescence can occur on new or older patios and is not usually serious. Salting can occur over days, weeks, or months but usually, it runs its course and (once cleaned) it does not return.
Efflorescence can occur just after pavers are laid as the base dries out. It also often appears after a period of wet weather early in the year. It is usually possible to remove with Floorseal Cement & Grout Haze Remover.
When cleaning work has been carried out you should wait at least 24-48 hours before any sealing work is planned (ideally longer). Once a slate patio has been washed down with water, cleaning solutions applied, rinsed off and probably pressure washed the slate may take some time to dry – possibly 48 hours or more.
It is good practice to thoroughly rinse the patio after cleaning solutions have been applied. For this reason, you will use a reasonably large amount of water so drying times can be slow. Damp patches may be noticeable in the joints, particularly if they are sand and cement for a few days after cleaning.
Please Click Here to view all our products & accessories for cleaning and sealing slate. This includes all our handy ‘how to’ guides for cleaning and sealing interior and exterior slate.
The information included in this article is not exhaustive. If you need further information please contact Floorseal or email info@floorseal.co.uk
