Tuesday, 20th February 2018 Limestone Paving - Don't black out!!
How to stop black limestone fading
Limestone paving has grown in popularity in recent years and is widely available from builders' merchants and DIY outlets. Although it is available in a broad range of colours, black and slate grey seem to be very much in tune with current fashion trends. However, there is one problem with "black" limestone - and that is it doesn't seem to stay "black" for very long.... In fact the deep "black" seems to fade out in a few months leaving a sort of "battleship grey" shade. Unfortunately many sellers of this paving seem to have a "black out" about this "black out" issue and customers don't find out until several months down the line.
Whether the true culprit is U.V light degradation or rain penetration is probably unimportant, the one question that callers to our advice line ask is; "can faded limestone be fixed???" Well the answer is "yes". Sealing it with Kingfisher "K-Seal" brings out the colour and adds protection because the first coat actually penetrates the substrate of faded limestone whilst the second coat forms a protective seal against the elements, deepening the colour. Beware cheap sealers or "enhancers" - these are often low grade formulations made with "Linseed oil" diluted in recycled white spirit and simply will not provide any longevity. "Kingfisher K-Seal" by contrast is a professional formula acrylic resin suspended in premium virgin solvent.
Ideally you should leave new limestone paving for 4 to 6 weeks before sealing it. This will allow time for any efflorescence (white salts) in the pointing mortar (joints) to develop as the mortar fully cures (approx. 1 inch per month). Wash the paving with warm water and a little soap and rinse thoroughly. Apply the sealer only to a dry surface and in dry conditions with no rain expected.
You can apply by brush but disposable roller works best. Avoid "ponding" of the sealer and read both the product data sheet and safety data sheet carefully before use.