When it comes to working with black limestone, these super-porous pavers have sometimes had a bad rap in the landscaping industry. Read our complete guide to black limestone paving including the best grouts to use (and the grouts to avoid), and how to seal, clean and restore this beautifully dark, natural quarried stone.
A bit of background on black limestone
When black limestone paving made its debut on patios up and down the country around a decade ago, these midnight-black paving slabs were all the rage.
Black limestone became a popular choice and celebrated for its naturally smooth surfaces and consistent monochrome finishes. Landscapers also loved how this natural paving material was much easier to cut.
Today, black limestone has seen a shift in popularity. Although aesthetically pleasing on installation, these ultra-porous paving slabs can be a more high-maintenance option for patios and are notorious for fading.
Let’s explore whether black limestone’s bad rap is warranted and the steps paving experts recommend for getting the most out of a limestone patio.
Does black limestone paving fade?
Homeowners must be aware that the most striking shade of black limestone – in other words, the blackest of the black – is when the paving materials arrive for installation.
Over time, black limestone will fade gradually to grey due to the elements – particularly the onslaught of rain and periods of sunshine.
The main reason why black limestone can fade is down to the slightly acidic rain we receive here in the UK. And this type of limestone does not work well with acidity.
When rain – or acid-based cleaning products for that matter – touch the limestone, a chemical reaction occurs that causes the colour to dull.
Natural ultra-violet rays from the sun can also pale black limestone.
All types of natural stone are expected to fade to some degree. With black limestone, this fading process is much more noticeable because of the striking contrast between the dark-black pavers on arrival and the greyish colours they can sometimes fade to.
Choosing a good quality black limestone from a reputable merchant can help in savouring the colour.
Some experts say that Kota Black Indian Limestone is slightly better quality with more fade resistance. Whereas the more readily available Kadapa Black Indian Limestone is softer, flakier and more chalky, and therefore more prone to fading.
The good news is there are things you can do to reduce this fading and bring the lustre back to your black limestone patio.
How to restore faded black limestone
Prevention is always better than cure. We’ll cover some important ways of laying and pre-sealing black limestone to prevent fading later on.
For now, let’s look at how to restore the vigour of an existing black limestone patio.
EASYSeal Back to Black Limestone is a penetrating resin that improves the lustre and appearance of black limestone to bring out the colour and intensity of the stone.
Quick and easy to apply, it can revive the limestone so it looks like new. EASYSeal is also stain and water resistant.
Before applying a sealant, make sure the surface is dry and free of stains and debris (see our cleaning tips below). If the weather forecast says rain at any time over the next 24 hours, you’ll need to hold off sealing the pavers for another day.
Always check the manufacturer’s application instructions first. Apply a thin and even coat with a sponge before leaving the pavers to dry.
Does black limestone need to be sealed?
Over time, black limestone paving – just like any paving – is likely to fade and attract dirt, grime or other unsightly stains.
If the patio or paved area receives a lot of foot or vehicle traffic on a regular basis, damage and fading is more likely to occur.
While cleaning black limestone in the correct way will certainly help you to combat stains (more on that soon), using a sealant will protect the slabs from most stains, plus algae and moss growth.
Applying a quality sealant will also help you maintain the darker shade of black on your limestone paving – which is likely to be the reason why you chose those pavers in the first place.
Although applying a sealant is not compulsory, doing so will help to enhance and protect your limestone pavers for years to come.
Note: when using certain grouts you will need to properly seal black limestone first. Read on to find out more.
How to enhance black limestone
Another way of enhancing the colour of black limestone is with Lithofin MN Colour Intensifier.
Primarily a colour enhancer, MN Colour Intensifer is ideal for porous, absorbent natural & manmade stone with rough and uneven surfaces.
MN Colour Intensifier is a ready-to-use siloxane impregnator that is solvent based and contains special colour intensifying components. The manufacturer also states that the product also offers a very good water seal.
Lithofin Colour Intensifier
If you want to seal black limestone without enhancing the colour, Lithofin Stainstop W is a water-based impregnating sealer that has been made to protect natural stone again oil, grease, dirt and water impregnating the surface.
Tips for sealing black limestone paving
When to apply a sealant to limestone paving is up to you and depends on the sealant you choose.
Some landscapers apply the sealant to the whole of each slab a couple of days before installing them.
Whereas other landscapers apply sealants such as EASYSeal after laying the pavers.
If you prefer to allow the pavers to naturally fade first, you may want to consider applying a sealant after a year or two of being in the elements.
It is generally recommended to seal the pavers every few years to prevent stains, fading and even reduce the need for regular cleaning.
What is the best grout for limestone paving?
Due to the susceptibility of black limestone, you must be careful about which grout you choose.
Best grout for strength: two-part epoxy resin
Ultimately, the grout to use with limestone – and certainly for black limestone – is a two-part epoxy resin grout such as EASYJoint PRO.
Made from a sand-based aggregate and resin, epoxy-resin grouts offer a much stronger chemical reaction than polymeric grouts or brush-in grouts.
Choosing the right grout is incredibly important with this type of paving material. If you use the wrong product or apply it incorrectly, the surfaces can go patchy.
Brush-in grouts for black limestone
Although not as strong as a two-part epoxy resin grout, some polymeric brush-in grouts are suitable for use with black limestone pavers.
One such grout is ProJoint Fusion from the team at Nexus.
Cement free and non-hazardous, ProJoint Fusion is a high-strength and all-weather jointing compound suitable for all pedestrian areas.
The formula is suitable for all types of natural stone and concrete paving.
Its easy application method allows DIYers and contractors to quickly point-up black limestone paving slabs and setts with a professional and long-lasting finish.
Can I use Flowpoint with black limestone?
A big word of warning: never use Flowpoint cementitious grout on dark or black limestone paving. When used with this high-maintenance paving material, Flowpoint can oxidise and leave stains on the surfaces.
If you opt to use a cement-based grout for pointing dark limestone paving, Fuga-Pave Flex CH grout is probably your best option.
Unlike some other slurry grouts, the manufacturer of Fuga-Pave says that the product can be used with black limestone. However, you must ensure you have sealed the limestone – on all sides of the slabs – before laying them.
When using a slurry grout like Fuga-Pave with black limestone, some extra care is required:
- The bedding mortar must be fully cured and the joints dry before grouting
- Ensure you’ve created a full-contact bed for the slabs
- Seal all slides of the black limestone before laying the slabs (allow to dry)
- Apply a primer (bonding mortar) to the full underside of each paver to secure the pavers in place and reduce the risk of efflorescence.
Read more tips on how to apply Fuga-Pave grout.
Although Flowpoint should never be used with black limestone, it is still a popular choice for pointing traditional limestone and all other types of natural and manmade paving materials.
Grouting black limestone in warm weather?
If you’re considering to work with black limestone during warm weather, experienced landscapers really advise against it.
Jim Stott from the Fuga-Pave team advises if you’re using Fuga-Pave: “Black attracts and retains heat. This will cause the polymers to cook – it will make the grout stick and become extremely difficult to move.”
“In warm weather, it is particularly important to make sure the surface temperature is not too high,” adds Ben Smith from the team at Nexus.
“As the dark coloured stone absorbs the sunlight, it increases the temperature of the flags by almost double the amount!”
How to clean black limestone pavers
When cleaning black limestone pavers it’s critical you use the right cleaning products for the job to avoid damaging the surfaces.
Listed here are the processes for cleaning both regular and tough stains from a patio, depending on the scale of blemishes you’re dealing with.
Never use acid-based cleaners
The most important thing to be aware of when cleaning black limestone is to never use an acid-based product to clean the surface.
When an acid-based patio cleaner – or one that contains hydrochloric acid – reacts with black limestone a chemical reaction can occur that might seriously affect the surface, even turning it white in patches.
An effective every day spray cleaner that is slightly alkaline should be used to clean black limestone.
Lithofin Easy Clean is a highly active cleaner that dissolves dirt, oil and grease and can be used on natural and artificial stone.
Read on for cleaning tips for everyday and tough stains.
Regular cleaning tips for limestone
If you haven’t sealed a black limestone patio, daily cleaning is recommended to ensure any stains do not become ingrained.
We recommend doing a small patch test of the cleaning product you’ve chosen before applying it to the rest of the pavers.
Daily cleaning is easy with a broom, cloth and non-acidic detergent or soap:
- Sweep away all the dust and debris from the surfaces
- Spray Lithofin Easy Clean on the entire surface, allowing it to work briefly
- Wipe the surface with a cloth or mop
- You may want to buff the surface with a dry cloth
Always follow the manufacturer’s instructions and ask if there are any variations for black limestone.
How to clean tough stains from black limestone
For tougher stains on black limestone, such as grease, oil or ingrained dirt, you may need to consider using a tougher cleaning product.
A more robust cleaner for natural stone is Lithofin Power Clean. Free of solvents and again mildly alkaline, this odourless and highly economic cleaner can also remove cement-based grout marks, and efflorescence or picture-framing from slabs.
Always choose quality products that won’t damage your paving.
Do a small patch test in an inconspicuous area before applying the cleaner to the rest of the paving.
Have a question about black limestone?
If you’re still unsure about which grout, sealant or cleaner to use with black limestone paving, get in touch with our team on 0330 122 1025 – or leave your question in the comments box below.
