How to seal Yorkstone flags & pavers

This article explains how to seal a Yorkstone floor. This relates to cleaning original interior Yorkshire sandstone flagged floors, including re-laid reclaimed floors, sandblasted York stone flagged floors and newly laid exterior Yorkstone pavers. We would recommend you prepare the york stone prior to sealing, so please read our article on how to clean and restore Yorkstone flags and pavers.

This information is relevant to both interior and exterior surfaces. This information can also be applied to sandstone lintels & walls.

There are always, at least, subtle differences between sandstones. Even though many sandstones have been grouped together and collectively given the title of ‘Yorkstone’.

The appearance of very old Yorkshire sandstone flags is different to a more recently quarried York stone. But usually, they can be treated in the same way as they have similar characteristics.

What should I seal Yorkshire sandstone with?

We believe the best form of sealer for York stone is a breathable impregnating sealer. It is possible to use a colour enhancing impregnating sealer on some Yorkshire sandstone flags – with care!

Newly laid ‘modern’ York stone should be sealed with an impregnator like Floorseal Natural Stone Sealer Breathe.

Or if the sandstone has natural colour variation, you can seal the surface with another type of impregnator called Floorseal Natural Stone Colour Enhancer.

Old interior Yorkshire sandstone flags are a little different & fall into 3 main categories.

• The first being floors which have been laid and never disturbed (usually on lime).
• The second category is made up of old flags which have been uplifted and re-laid with a damp-proof membrane and repointed with modern pointing.
• The third category could be either of the above but a floor which has been sandblasted.

Impregnators are suitable for use in listed buildings or for generally conserving stone. They do not and cannot create a surface film or sheen, they are 100% breathable.

Our impregnating sealers will make the surface of Yorkstone resistant to water and oil-based staining. This in turns helps to prevent organic growth and frost damage. Both sealers can be used on interior or exterior surfaces.

How to seal old undisturbed original interior Yorkshire sandstone flags

Floors that have never been disturbed are usually obvious due to how the slabs have been laid edge to edge. This method of laying the slab is known as monolithic fixing. There is no real pointing material between the slabs, sometimes none.

At the time of fixing the slabs, a little of the lime screed underneath may have been pushed up to fill some gaps. Sometimes gaps between the slabs have appeared over time due to settlement.

Old, flagged floors will not have a damp-proof membrane (unless added later).

Not having a damp-proof membrane is not necessarily an issue. Many old floors are perfectly dry. Floors which are damp have often become softer over time, the surface can be de-laminating or displaying efflorescence.

Regardless of the above points we still recommend sealing with a breathable impregnator. This is because older York stone floors may have vapour passing through them.

We do not recommend sealing old Yorkshire sandstone flagged floors with a colour enhancer. This is because older floors are often marked, stained, or impregnated with a variety of chemicals. This staining can be enhanced by using a colour enhancing sealer.

Older floors may not even be obviously marked, much of the life of an old Yorkshire sandstone floor is explained as ‘character’. Old sealers or sub-surface stains can affect how a colour enhancing sealer enhance the stone. This is due to the varying levels of porosity which have been created by 100 years+ of contaminants.

The level of porosity in the stone can be due to natural shading or veining. It can also be created by contaminations of old paints, bitumen, oil, old sealers & cleaning products. This is why colour enhancing sealers and some topical (surface) sealers can be affected.

Older Yorkshire sandstone floors are also often quite grey in colour, so are less responsive to colour enhancers.

For most old undisturbed York stone floors, we recommend sealing with Floorseal Natural Stone Sealer Breathe. It is the best way to seal an old York sandstone floor. This is acheived without altering the colour, allowing moisture vapour transmission, and retaining the natural appearance of the stone.

Old Yorkstone floors often have visible contaminations, this includes re-laid or reclaimed York Stone floors. This is a good reason to use invisible impregnating sealers like Natural Stone Sealer Breathe. Therefore there is no possibility of a problem with patchy colour enhancement due to contaminants.

Sealing re-laid or reclaimed interior Yorkshire sandstone flags

The information in the preceding paragraphs also applies to re-laid York stone flagged floors. The only significant difference is a re-laid floor will usually have a damp-proof membrane (DPM). It is unlikely the floor will have been re-laid without a DPM – even if it’s a more natural method.

The pointing is usually a Portland cement and sand mortar, which does not breathe. In contrast, lime pointing will allow moisture vapour through. Many builders will avoid lime pointing if a damp-proof membrane has been applied. This can be because it is not required if the floor is laid on a DPM. Lime is also more difficult to work with if you are not familiar with working with it!

The width of the pointing in re-laid floors is more likely to be 25mm. Fashions change, people like wider joints and builders find them easier to point!

We recommend sealing re-laid Yorkshire sandstone flags and pavers with Floorseal Natural Stone Sealer Breathe. This sealer does not alter the appearance of the stone, and allows moisture vapour transmission but resists water and oil-based staining.

How do I seal a sandblasted Yorkshire sandstone floor?

Possibly with some difficulty as the surface will be very porous and prone to staining!

The difference between an old sandstone and a recently blasted floor is that the older floor will have been subject to wear. Sandblasted floors are lighter in colour and more porous.

Yorkshire stone is quite coarse and will, over time, wear with foot traffic. They also pick up dirt and contaminations of old sealers and cleaning agents. Older floors seem less prone to staining due to the fact they have become a deeper colour with less porosity.

If you sandblast a floor the surface lightens in colour and becomes more ‘open’ and porous – it is actually a much rougher surface.

The best way to seal a sandblasted surface is with an impregnator. Make sure you saturate the surface. The coverage rates of most sealing products (regardless of brand) are not relevant as the porosity will be greatly increased.

Our best advice is to really saturate the surface applying the product twice approximately an hour apart. It is notoriously difficult to fully seal a sand blasted York stone floor. But saturation with an impregnating sealer, with care, should seal the surface.

The location of the floor is also a factor i.e. a busy kitchen or hallway has the potential to become stained than a room with less traffic.

Sealing newly laid exterior Yorkstone

When sealing newly laid ‘new’ sandstones i.e York Stone which has been recently quarried you should use an impregnator.

Floorseal Natural Stone Sealer Breathe is suitable for sealing any type or age of sandstone. This is certainly our recommended sealer to seal every type of York sandstone, regardless of colour or age.

But you can use Floorseal Natural Stone Colour Enhancer on newly quarried colourful York Stone.

The application process is the same; the only difference being the sealer slightly enhances colour. This enhancement is subtle and natural and works well with York Stone which shows colour variation when dry.

Never use a colour enhancer to produce colour in a sandstone which has no colour. This is typical of Kandla Grey Indian sandstone or Yorkshire Grey flags. Yorkshire Greys are usually original interior floors or reclaimed floors which can be found inside and outside a property.

Are your sealers pet friendly?

Yes, our sealers are pet friendly, both are water-based and do not contain VOCs. These sealers have a water-based carrying agent which evaporates leaving a sub-surface polymer in the pores of the stone.

It is for this reason these sealers are also human friendly!

Dogs, however, do not seem to be York Stone friendly as they contribute to floors which become grimy quickly!

In conclusion

Natural Stone Sealer Breathe – A breathable sealer which resists water & oil-based staining & inhibits organic growth. It will not change the appearance of the surface it is applied to. Once sealed the surface still retains an unaltered natural matt finish.

Natural Stone Sealer Breathe is suitable for listed buildings, rubble-filled walls and floors with no DPM. Can also be used where no change in the appearance of the surface to be sealed is a priority.

Natural Stone Colour Enhancer – A breathable sealer which resists water & oil-based staining & inhibits organic growth. Like Natural Stone Sealer Breathe but deepens colour to create a subtle colour enhanced natural matt finish. Suitable for sealing sandstones with visible colour or veining when dry. Not recommended for plain greys or older floors.

Please Click Here to view 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 info@floorseal.co.uk our web address is www.floorseal.co.uk.