Restoring and Sealing Faded Black Limestone Paving using NCC 'Return to Black' Stone Sealer.
- In recent years there has been a bit of an explosion across the UK in the use of 'natural' Black Limestone paving that is very attractive and works well. The only issue in fact is that the beautiful black (well very dark grey) paving, only stays black in the ground as the bedrock, which is below the ground, below the surface, and is not exposed to UV light and weathering.
This is because of atmospheric oxidation of black carbon-based pigments in the rock, with simultaneous bleaching action of UV light in the sunlight - and so it goes grey. However, as if by magic, when it is wetted again, then the underlying black pigment colour in the stone is refracted through the water on and in the surface pores, and so the paving appears to be black!
As we all know: 'The customer is always right', and interestingly the stone is often strangely cheap (now guess why...?), and if we were to give it the right descriptive stone paving name, this should probably now be called: ‘Black for a few weeks after laying flat on the ground, or when it is completely wet Limestone Paving, otherwise and when dry this is really Light Grey Limestone Paving’. It is fine as durable and hard wearing paving – BUT WILL NOT ALWAYS BE BLACK.
As a result of this phenomenon, there are always many people around the country who are somewhat disappointed with their no-longer-black, black limestone patio, well in terms of its light grey colour anyways. In recent years there have been numerous products produced to make the light grey limestone go ‘Back to Black’, and which are usually based on black pigments in an acrylic resin dispersion (the same basis as most gloss paving sealers). However, the glossy finish only great, until you walk over it a few times, and then this ‘trafficked’ area becomes clearly visibly and soon you have a different sort of unsightly result! – We think it looks worse than the light grey that is at least black every time it rains, just not when you are using your patio in the sunshine!
However, we have worked with some clever resin specialists and a couple of years ago they came up with a much better water dispersed, acrylic resin-based product that gives a deep and dark, but matt finish, which is also very resistant to foot traffic across it. This advanced product is now called NCC ‘Return to Black’ Stone Sealer and is now available in our Online shop.
NCC ‘Return to Black’ Stone Sealer gives a much more natural stone appearance and weathers and wears far more unnoticeably, and after a few years it can also easily be reapplied if required - and without the need for chemical pre-treatments.
Characteristics / Advantages
• Pigmented, matt black sealer & enhancer
• Natural matt finish
• Water dispersed (no solvents & non-flammable)
• Easy to use - brush and/or roller applied
• Protects against staining and frost damage
• Inhibits green growths
• Restores the original dark appearance of your stone
• Uniquely gives the colour of a wet-look sealer without the gloss
Application - Directions for use:
Wear gloves and ensure that any surfaces not to be treated are suitably covered and protected. Shake bottle well before use. Apply a small amount to the surface and spread out evenly using a paint brush or a suitable foam roller. Allow to be absorbed and dry thoroughly, then apply further coats (max 3) at approximately 2 hourly intervals, until the desired depth of colour has been achieved. NCC ‘Return to Black’ Stone Sealer can be applied over a wide temperature range of from 5°C to 25°C.
Typically Coverage / Consumption is between 5 to 10m2 per lite per cost depending on surface porosity.
Leave to dry naturally, and for honed and smooth surfaces it may be necessary to take off any excess using a soft cloth. Protect the freshly treated surfaces from rain and any other water or contaminants, and do not walk on the surfaces for at least 4 hours after the final application.
Professional Application Tip: Allow the newly treated surfaces to cure and harden for at least 24 hours and then rinse with a dilute (1 to 10 with water) solution of NCC Grime Remover, as this will help remove any excess sealer and ensure a uniform colour and finish. Before allowing traffic, carefully test the surface has fully hardened in a few areas e.g. by gently rubbing with white cloth or paper towel to make sure that it is completely dry and colourfast.
Important note: This product is a permanent black stain solution that will darken the surface of the stone and the grout joints making it very difficult to remove once applied, therefore always test on an inconspicuous area before general application and do not walk on the treated surfaces until the solution has completely dried.
If you need further advice or assistance, call our specialist team on 01257 266696, or email: technical@nccstreetscape.co.uk
