How to clean & renovate Yorkstone flags & pavers
This guide explains how to clean and renovate a York stone floor. The same principles apply to cleaning walls and lintels. You can apply these techniques to both interior and exterior floors and walls.
York stone, also known as Yorkstone or Yorkshire sandstone can be older flags or new pavers. There are some differences between cleaning older interior Yorkshire sandstone flags and newly laid exterior flags. To find out about sandstones in general, read more here.
Very old York stone flags which have never been disturbed are monolithically fixed. There is virtually no gap between the slabs and will not have a damp-proof membrane.
Old slabs which have been uplifted and re-laid often have a wider gap between the flags. Typically, this gap is 25mm wide and will have been pointed with a Portland cement and sand mortar.
Exterior flags and pavers may have a Portland sand and cement joint or a modern brush in compound could have been used. These slabs will typically have a joint of approximately 25mm wide. If the joint is narrow, almost non-existent the pavers will be original and it is unlikely they have been disturbed.
The information contained within this article is not exhaustive. There is a wide range of sandstones which have all seem to have become known as ‘York stone’, but here will be differences in colour, porosity, condition, and hardness.
The condition of your York stone flags or pavers
The condition of your York stone flags or pavers will affect the overall result of the clean. Yorkshire sandstone flags which have been buried under screed or bitumen may need additional work beyond cleaning.
Badly stained flags or flags which have become soft and are de-laminating may require sandblasting to renovate them. This may also be the case if they have had multiple layers of polyurethane varnish applied.
As a rule, grime, dirt, and some sealers can be removed. Organic contaminations on exterior pavers, walls or lintels can be cleaned off. The effects of weathering and long-term organic contaminations or other staining may not be possible to remove.
Testing with different cleaners is usually advisable on old badly marked stone.
How to deep clean an interior Yorkshire sandstone flagged floor
If you are deep cleaning an interior York stone floor, we recommend Floorseal Stone Floor Cleaner.
Floorseal Stone Floor Cleaner is very effective at removing built-up grime and dirt. It can be applied at a highly diluted rate of (1:10 with water) all the way up to being applied neat.
Stone Floor Cleaner is brilliant at cleaning old interior Yorkshire sandstone flagged floors, floors which have blackened over time due to constant mopping can really clean up with a little effort.
Stone Floor Cleaner can be applied via brush, mop, and bucket or in conjunction with a slow speed rotary and wet pick-up vacuum.
Always rinse after use with plenty of clean water. You can add a tiny amount of neutralising agent to your rinse water to neutralise the floor. This means adding a small amount of an acidic solution, such as a white wine vinegar or our Floorseal Cement & Grout Haze Remover.
You will only need 50ml to 100ml (diluted into 5-10 litres of water) of acidic solution to neutralise, even if the Stone Floor Cleaner was applied neat. Rinsing with just water is also effective at neutralising any form of cleaning agent. This method of neutralising is often adequate providing you have rinsed the floor a few times.
When neutralising the product on acid-sensitive surfaces like limestone, travertine, marble etc you should just heavily rinse the area with clean water.
Please note you should apply this product with care around painted, varnished surfaces, or metallic surfaces. We have successfully used this product on numerous occasions to clean kitchen floors, avoiding kitchen units etc without a problem.
When working up to walls, corners, or kitchen units you can apply this product using a brush. After a suitable dwell time of approximately 15 minutes, remove any dirt by using the same brush, and blot off the area with cloths.
Cleaning exterior York stone flags, pavers, walls, or lintels
Please use Black Spot Remover Plus for cleaning exterior York stone. This product can be applied neat for the removal of organic contaminations like algae and black spot lichens on horizontal or vertical surfaces.
Black Spot Remover Plus will also remove general dirt, some oils, bird droppings and other organic contaminations.
This product can be used in conjunction with Floorseal Cleaner Additive. Cleaner Additive is a thickening/foaming agent which prevents the remover from drying prematurely and helps the remover stick to vertical surfaces.
Obviously, pressure washing is highly effective at cleaning exterior York stone floors. This will remove most contaminations except for black spot lichen. Use Floorseal Black Spot Remover Plus to remove black spot lichens.
Treating interior sandstone lintels for moulds
It is also possible to treat interior lintels or mullions around windows which are suffering from mould. Please use our Black Spot Remover Plus. It can be used in conjunction with Cleaner Additive and left to dry on the surface.
Apply carefully with a paintbrush either diluted 1:1 with water or neat. This will remove organic growth such as black mould and any other organic contaminations.
How to remove paint from York stone floors
Floorseal Stone Floor Cleaner will remove most paint with adequate dwell time. We have found that soaking paints with just water, in conjunction with a small amount of Stone Floor Cleaner, works well.
If the sandstone is honed smooth, a flat a sharp scraper can be effective. For rougher riven York sandstones, a stiff hand brush can be useful. It is also possible to use a narrow brass handheld brush. These are softer than normal steel/wire brushes.
Often a good long dwell time (soaking for long periods of time) is the most effective method of removing paint.
Solvent-based products for paint removal are also available. However, we have found that they are not that effective, they smell awful and can lead to solvent staining.
Removing oil stains from York stone
Oil marks are possible to remove with Floorseal Stone Floor Cleaner. You may need to use the product neat and allow lots of dwell time i.e. soaking.
Oil marks are hard to remove due to being held deep within the stone and can have oxidised. There are methods to remove them using poultices but are beyond the scope of this article. They often fail but can be used overnight to draw deep stains from the stone.
For context, a poultice would be where a powder is mixed with Floorseal Stone Floor Cleaner and then applied to the stain. Cover the stain with a thin plastic sheet and tape it to the floor. Puncture the plastic numerous times so, as the powder dries, the stain removing solution (after having sunk into the stain/stone) dries slowly pulling the stain out of the floor.
Be aware some oil stains will not respond; you could also leave/create a halo in the stone from where the poultice was applied!
Our preferred method was to clean interior York sandstone flags with Floorseal Stone Floor Cleaner. This would remove most, if not all the marks, we would then consult with the customer over any further work.
Removing cement or grout from interior or exterior York stone
We recommend Floorseal Cement & Grout Haze Remover for the general removal of cement-based products.
Floorseal Cement & Grout Haze Remover can be applied to York stone and general sandstones. Do not apply to acid-sensitive surfaces like limestone, marble, travertine, or concretes.
The product can be diluted from approximately 1:4 with water or applied neat. Try to avoid kitchen units and metal surfaces, wipe down immediately if the solution encounters these surfaces.
Hazes and smears of grout, cement, or lime are easy to remove. Larger lumps may need chipping/scraping off before the haze is removed.
As with all cleaning products – test before use!
Be aware some floors described as just natural stone or even sandstone flags are acid sensitive. An example of this is the local stone found in the Cotswolds. This natural stone is sometimes described as sandstone, it is in fact Oolitic limestone so acid-sensitive – beware! Always try to identify your stone before using an acid.
Always rinse away this product with plenty of clean water and allow the floor to dry.
How to remove efflorescence from York Stone
The removal of efflorescence is usually easy, it can often be carried out with just a brush – if the efflorescence has appeared recently.
Efflorescence is a simple salt deposited on the surface after moisture has evaporated. It can be removed by brushing it away or applying Floorseal Efflorescence Remover.
Brushing & treating with a product can both remove salting, but it can return if the underlying issue is not resolved. This may be because the floor is inherently damp, or it occurs at certain times of the year. If so, the salting can become a ‘crust’ and is difficult to remove.
You may need to remove the worst of the crust via a mechanical action, chipping or brushing – then apply Efflorescence Remover. Take care not to damage the stone when chipping, scraping or brushing the stone.
Once the efflorescence is removed check for any re-occurrence. If efflorescence reoccurs it may be linked to a newly laid exterior stone. Or the floor has an ongoing damp issue, typical of floors laid on earth.
Please be aware that efflorescence can occur after deep cleaning the floor. Particularly old floors where there is no damp-proof membrane present. It is not serious, the salting can usually be removed by brushing it away.
How to remove rust marks from York stone floors
Removing rust can be carried out with Floorseal Rust Remover for Stone. It is a non-acidic solution which can be also applied to acid-sensitive stones.
This product is to be applied neat (it turns purple when reacting with rust) and should be rinsed away within 10 minutes of application. Do not allow the product to dry on the surface.
Floorseal Rust Remover for Stone will remove surface contaminations and ingrained rusting. With heavier rust marks, you can apply the solution multiple times to remove all rust traces.
Stripping old sealers before sealing
The removal of old topcoat water-based acrylics is possible with Floorseal Stone Floor Cleaner. This product can also break the surface tension left by old impregnating sealers.
The removal of old sealers is problematic and not always economically possible. Solvent-based acrylics are very difficult to remove and often require a solvent-based stripper to be successful.
Polyurethane sealers are very difficult to strip from interior floors. They require a very powerful stripping agent – These stripping agents are noxious! They create unpleasant fumes and are generally really unpleasant to work with.
In our experience, if polyurethane has been applied to an interior floor, many people prefer to sandblast the surface (where possible). This is often carried on old Yorkshire sandstone slabs as a property is renovated.
It is not possible to fully remove old impregnators or colour enhancing impregnators. Cleaning will only break surface tension and allow more impregnator to be applied. Over time old impregnators will break down but it is a slow process.
If the stone has a shiny topical sealer applied i.e. one that dries as a film on the surface, they are hard to remove. The exception to this is wax, but wax is rarely applied to York stone.
Cleaning the remains of screeds & bitumen
Screeds and bitumen often lift away from the sandstone in sheets, so appear to be easy to remove. Unfortunately, we have found that bitumen has usually penetrated the surface of the stone. This is common on old interior Yorkshire sandstone flags. The traces of bitumen can still be found on exterior York stone flags. Many are reclaimed flags which have been used to make patios.
Screeds, if cement-based, can cause the surface of the stone to become soft. This can also happen if old sandstones have been under laminate for a long time. This is due to trapped moisture which collects at the juncture between the stone and the screed.
Old floors appearing from under bitumen and screeds can be in poor condition. If bitumen has been applied sandblasting is often the only solution. If the surface has become soft and is de-laminating the same applies.
It is possible to remove any cement-based screed residues with Floorseal Cement & Grout Haze Remover.
To date, we have not found any effective way of using a cleaning agent to remove ingrained bitumen residues.
We have used various brush attachments, fitted to rotary machines, to test their effectiveness in removing the issues listed above. We have found them to be ineffective. This includes diamond pad systems, diamond brush systems & silicon carbide brushes.
If an interior York stone flagged floor is heavily stained with bitumen or if it has become soft and is de-laminating then sandblasting offers the best solution – it is a last resort though.
Obviously, a grimy or even blackened floor can respond to intensive cleaning with Floorseal Stone Floor Cleaner. Sandblasting is a last resort for any interior floor.
Exterior York stone floors can be cleaned with pressure washers, so this is the first port of call for an external floor and is usually all that is required. The exception to this is the removal of black spot lichen which can be carried out with our Black Spot Remover Plus.
Pointing Yorkshire sandstone flags
When pointing an interior floor, we have pointed with both lime and sand & Portland cement mixes, depending on the situation. On very old floors where there is a narrow, almost non-existent joint it is time-consuming work.
We have widened some narrow joints to avoid the patchwork quilt effect i.e some areas obviously pointed and others not. The Victorians followed a system of floor laying known as monolithic fixing. In other words, they butted one slab directly up to another. Lime from the ‘bed’ underneath was pushed up from below, due to the weight of the slab.
Over time some joints become wider and others not. In this situation, if you repoint without remedial work you will end up with the patchwork quilt effect. It was, for this reason, we often widened joints to at least 4mm, when pointed the floor looked more attractive.
If an old floor is being uplifted most builders will relay the floor with a 25mm joint and also add a damp proof membrane under the floor. This wider joint means it is possible to identify a stone floor which has been disturbed. Or perhaps reclaimed York Stone slabs fitted where previously there were no flagged floors present.
Exterior York stone floors formed from older slabs look prettier with a sand & cement mortar. Many landscapers will use a brush in compound on newly laid ‘modern’ York stone pavers.
Sand & cement mortars are usually stronger than brush in compounds. The resin-based brush in compounds should not be used indoors, they are weaker and usually appear out of character.
Floorseal Stone Floor Cleaner is used to remove most ingrained dirt/marks and oil marks. This product can also be used to remove paints and old acrylic sealers and breaks the surface tension created by old impregnating sealers.
Floorseal Cement & Grout Haze Remover use for the removal of cement-based grouts, screeds, and general cement. Can also be used to remove the haze from lime pointing.
Efflorescence Remover will remove salting left on the slab from moisture passing through from the base or left by evaporating water.
Rust Remover for Stone is a non-acidic rust remover suitable for use on most kinds of stone. This product can be used on acid sensitive surfaces but proceed with caution on coloured concretes.
Black Spot Remover Plus can be used on exterior sandstone to remove black spot lichens. It will also remove other organic contaminations like algae and bird droppings. This product can also be used on interior lintels, removing black mould which has formed around windows.
Our black spot remover can be used in conjunction with Floorseal Cleaner Additive. Cleaner Additive will thicken the product creating a slight foam. It helps to prevent premature drying and makes the remover cling to vertical surfaces.
Please Click Here to view all our products & accessories for cleaning and sealing York sandstone. This includes our handy ‘how to’ guides for cleaning & sealing interior and exterior York sandstone.
The information included in this article is not exhaustive. If you need further information please contact Floorseal on (01484) 861461 or email us firstname.lastname@example.org our web address is www.floorseal.co.uk
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