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How to seal & colour enhance black limestone
How to seal and colour enhance black limestone

Apr 15, 2021

Looking for the best way to seal black limestone paving?

This guide explains how to seal black limestone patios using Floorseal Black Limestone Restorer. There is also additional information regarding the pre-cleaning of black & grey limestones.

The subject of how to create a ‘wet look’ finish is discussed and the various ways of doing this.

This article has primarily been written to understand how to clean and seal external black limestones. Whilst the information is relevant to interior black limestones there are a few other options when sealing internal floors. Click here to read our article about cleaning and sealing interior black limestone floors.

faded black limestone tends to have a 'dusty' look
A typical ‘faded’ black limestone patio.

Which product should I seal and colour and enhance a black limestone patio with?

We recommend using Floorseal Black Limestone Restorer to seal & colour enhance black limestone pavers.

Black Limestone Restorer is a fully breathable impregnating sealer so it will not trap moisture. Black Limestone Restorer seals & deepens the colour of limestone, so appears ‘blacker’.

Black Limestone Restorer dries to a matt finish, so your limestone pavers retain their natural appearance. Enhancing the colour of black limestone also enriches its appearance. A little like dampening the stone but without an associated shine.

Black Limestone Restorer is a premium grade breathable impregnating sealer. It is a particularly strong colour enhancer which resists oil & water-based staining. This black limestone sealer can be used to seal both new installations and also to revive the appearance of older faded limestones.

Black Limestone Restorer will also correct mild acid etching from accidentally washing black limestone with an acid-based cleaner.

How does Black Limestone Restorer work?

Black Limestone Restorer is a breathable impregnating sealer which also contains a colour enhancing polymer.

Impregnators, like Black Limestone Restorer, always leave natural stone with a natural matt finish. This is because, as the name suggests, an impregnating sealer soaks deep into the pores of the stone. The surface becomes resistant to water and oil-based staining, without an actual lacquer forming on the surface.

Therefore, you will not see an obvious sheen or film form on the surface of the stone. The colour change you see is the product changing the colour of the stone from within – rather than a non-breathble coating being created on the surface.

In other words, the product is ‘in’ the stone not ‘on’ the stone. Black Limestone Restorer becomes deeply meshed into the pores of the stone protecting it from within.

Deepening the colour of once darker limestone’s will turn a washed-out lifeless grey colour back to black. The stronger the colour enhancer used, the ‘blacker’ the stone becomes.

Black Limestone Restorer waterproofs the stone and also resists oil splashes. This sealer is a 2-in-1 product which carries out two important tasks – sealing the surface and colour enhancing.

Importantly this sealer is not subject to wear from foot traffic and particularly the effects of damp weather, it is not a surface coating.

How does this black limestone sealer work if it does not form a skin or lacquer on the surface?

Surface sealers are sometimes referred to as topical sealers or ‘wet look’ sealers – they dry on the top or surface of the stone.
Topical sealers may not deepen the colour of black or grey limestone’s to the same degree as an impregnating colour enhancer. Externally they may cause moisture clouding this is for a variety of reasons, such as:

  1. The application of the product to a damp stone i.e moisture present in the stone at the point of sealing.
  2. The sealer becoming damp/wet just after application due to rain.
  3. The limestone curing slowly and then morning dew (or frost) contaminating the sealer.

Topical sealers will, at some point, need stripping back which is fairly labour intensive.

Floorseal Black Limestone Restorer impregnates the pores of the stone so deepens colour from within. This product also resists water and oil-based staining without the need to form a skin on the surface.

Therefore, Black Limestone Restorer does not require stripping as it does not wear, blister, flake, or peel. This sealer is not sensitive to the effects of damp or wet weather which many surface coatings are.

In the future, if your limestone pavers need to be colour enhanced again, it is possible to simply reapply the product.

transforming the finish on black limestone

How to make black limestone look wet

The term ‘wet look’ causes some confusion. Wet look finish means different things to different people! Wet look can mean a product which creates a sheen, or a product which produces depth of colour without a sheen.

It is important to understand that Black Limestone Restorer deepens colour but does not create a sheen. A little like wetting with water but the stone retains its natural matt appearance, once cured.

What does a shiny wet look sealer do that is so different to your product?

Most retailers regard a wet look finish as something that will mainly create a shine. This shine could be either a satin or gloss finish. A wet look finish may deepen the colour of the stone, but it is not actually its main purpose. A wet look sealer is a form of topical sealer, it dries on the surface of the stone and reflects light i.e. it creates a sheen.

Anything which is applied to external limestones creating a sheen usually means more work to maintain its appearance. This maybe due to over application, trapped moisture issues & a general lack of depth in colour.

Most of the issues with wet look topicals sealers, which create a sheen, revolve around the our typically British damp weather. In other words trapped moisture leading to clouding and general loss of appearance.

The difference with this product is Floorseal Black Limestone Restorer seals and deepens colour from within

On the other hand a ‘wet look’ sealer creates a surface sheen which may deepen colour, but with ongoing associated maintenance!

Black Limestone Restorer could be described as having a particular type of ‘wet look’ finish, as it replicates the effect of dampening the stone with water. But importantly the depth of colour produced has been achieved without the need for a surface coating.

A little like oiling wood – the sealer soaks into the surface, the excess is removed, therefore the material deepens in colour.

What are the benefits of sealing black limestone with Floorseal Black Limestone Restorer?

Black Limestone Restorer will leave the surface with an enhanced, matt, natural, & breathable finish.

The colour enhancing element of this product will darken the limestone enriching colour. An obvious choice for sealing darker stone without creating a shine. Darker stone looks healthier when sealed & colour enhanced.

A single application of Black Limestone Restorer is sufficient to colour enhance and seal black limestones

The surface of your limestone may weather over time, but our sealer will not need stripping before any future reapplication is made. Once the surface becomes porous again you can simply reapply the sealer.

Black Limestone Restorer offers maximum surface protection and colour enhancement whilst retaining a natural appearance.

This sealer achieves large coverage rates as it has a high active content and only needs one application to work.

seal black limestone paving for enhanced colour appearance and longevity

How to apply a black limestone sealer & colour restorer

We recommend applying Black Limestone Restorer using a paint pad or microfibre flat mop, or cloths. It is possible to apply with a brush or roller with care.

You should only work in small areas at a time, so you can seal the surface and remove the excess as you work across the floor. You must always remove the excess before the sealer becomes tacky – use dry microfiber cloths to do this.

Working in small areas is the easiest & most efficient method to apply the product. You can reach into the floor area and once complete move back to seal a new area, thus removing all excess as you go. This means you never actually step into an area you have just completed.

Please remember, this is a one application product so you only need to apply the sealer and remove the excess once. Have a lots of dry cloths to hand so you can remove the excess easily, just two cloths for 30m2 is not enough!

Change your cloth as soon as it becomes dampened with excess product. You need to buff the excess sealer from the surface of the stone, so the limestone is dry again. It should have a matt appearance when you have removed all the excess.

After removing the obvious excess, do not be afraid to leave the surface for a few minutes and then wipe over it again. It is not possible to remove the sealer already locked into the surface. You cannot over wipe the surface, you are only removing excess product, most of the sealer will have soaked into the stone.

Never simply apply the product to the limestone and leave it to dry. There will be some excess product if you have reached saturation, it needs to be thoroughly wiped off.

The length of time left before removing excess sealer varies but we have found anywhere between 5 and 20 minutes is optimal. Carry out a small test area to gain a timing that suites the conditions on the day.

Never apply this sealer to damp stone and make sure the surface is clean before application. This product will reach full strength over 24-48 hours, but you can walk on the surface as soon as its dry.

Do not apply when the air and stone temperatures are particularly high or low. Always carry out a test patch to check for colour suitability.

The ideal conditions for application are dry weather without rain for at least 24-48 hours.

How do I clean black limestone before sealing?

We would recommend pre-cleaning black limestone with Sealer Residue Remover before applying the sealer.
Floorseal Sealer Residue Remover is a non-acidic cleaning solution which tackles general dirt, dust, and non-visible traces of brush in compound residues.

If you have made an obvious visible mistake with a brush in compound or resin based grout you should use Jointing Compound Residue Remover. This product is for the removal of obvious unsightly mistakes that can clearly be seen.

It is important to ensure the stone is fully porous before applying any kind of sealer.

You can pressure wash external black limestone but be careful not to hold the lance too close to the surface. Black limestone is a soft stone so you could mark the surface with a turbo nozzle.

Under no circumstances should you ever clean limestones with acid-based solutions as they will attack the limestone itself. Cements are made from limestone! If an acid-based cleaner is being used to dissolve traditional sand and cement pointing hazes (or grouts), it will also dissolve the very surface of the stone you are trying to clean!

Trying to remove a thick cement haze or brush in compounds is a separate subject. But as a general guide take great care as the attempts to remove contaminations often have a detrimental effect on the stone.

As previously discussed incorrectly using a pressure washer can disrupt the surface of the limestone, leaving light grey stripes on the stone.

Heavily wetting with water and light agitation can break down some hazes. Beware of using abrasive techniques to remove hazes as this can leave the stone looking very patchy after it has fully dried out.

Some general patchiness or fading can be corrected with Black Limestone Restorer as it deepens the colour of the stone.

Coverage

Black Limestone Restorer will cover approximately 25m2 in one single application. Please be aware that coverage rates always vary depending on the individual porosity of the limestone being treated. 35m2 is the maximum coverage rate we have acheived with 1 litre of product.

colour enhance black limestone for a deep, dark look and water & stain repellency

In conclusion

Black Limestone Restorer will make the darken the colour of black and grey limestone. This sealer will even out faded limestone or a general patchy appearance. It will correct light acid etching caused by accidentally washing the surface with an acid-based solution.

Black Limestone Restorer is an opaque liquid, it does not contain a dye or a pigment. It is totally breathable so will not cause moisture clouding issues.

To see further information about Black Limestone Restorer please click here. It is possible to purchase a sample if required.

The information contained within 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

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