Stone sealing and impregnation

Why stone sealing is needed

Natural stone is porous. To varying degrees and at varying rates, every stone we work with absorbs moisture, oil and dissolved contamination from whatever sits on its surface. Marble will absorb a red wine spill in minutes. Limestone is even more absorbent and will pull in shampoo, cosmetics, olive oil or tannins over a few seconds. Travertine has the added complication of natural voids that trap dirt and moisture. Terrazzo behaves like the aggregate it is made from, usually calcium-rich and absorbent. Granite is the least porous but is still vulnerable to dark oils and specific acids. In every case, unsealed stone stains.

Sealing is the only preventive answer. A correctly specified impregnating sealer lines the pore structure of the stone from within, so that moisture and oil sit on the surface long enough to be wiped away rather than being absorbed. It does not form a film. It does not change the look. It does not peel or craze. When it is time to re-seal (every 18 to 36 months in typical residential use, depending on the stone), the product tops up rather than needing to be stripped off. Unsealed or poorly-sealed stone, by contrast, is where nearly all the staining problems we see on London floors and worktops originate.

Signs your stone may need sealing

• Water beads poorly or disappears into the stone within a few seconds of a droplet test
• Oil, wine, cosmetic or coffee marks have left visible stains that cleaning will not lift
• A limestone or travertine floor has darkened in specific patches where liquid has sat
• A marble or granite worktop shows colour changes around the sink, hob or tap area
• It has been more than two years since the stone was last sealed
• The floor has just been restored (honed, polished or deep cleaned) and the freshly opened surface needs protection
• You have just bought the property and do not know when the stone was last sealed
• A previous sealer looks cloudy, patchy, peeling or yellowing (that is a topical sealer failing, not an impregnator, and it needs stripping before re-sealing)

Suitable stone types and settings

We seal marble (bathroom floors and walls where shampoo, perfume and cosmetics create staining risk, and marble kitchen worktops), limestone (the most sealer-hungry stone we work with, French Moleanos and Portland especially, needing re-seal every 18 to 30 months), travertine (patios and pool surrounds against frost and algae, internal bathroom travertine against soap and shampoo), granite (darker granites benefit significantly, lighter granites usually do not need sealing), terrazzo (period Italian terrazzo absolutely needs sealing after any restoration), slate (riven slate kitchen worktops and period slate hearths), sandstone (York stone and Purbeck paving against weather and organic staining) and period Victorian and Edwardian tiles (breathable impregnator only, never a topical, period earthenware must keep releasing moisture).

There are two kinds of sealer and they are nearly opposites. Topical sealers sit on top of the stone as a film, give a "wet-look" gloss, and peel off unevenly. We almost never use them. Impregnating sealers sink into the stone itself and line the capillaries from within. That is what we specify, on almost every stone, almost every job.

Results and expectations

A correctly sealed floor or worktop looks identical to the day it was laid, but with a meaningful protective margin against staining. Water and oil bead on the surface and can be wiped away before absorption begins. Day-to-day cleaning is easier because dirt has less to grip onto. In residential use, a properly applied impregnator lasts 18 to 36 months on limestone, 24 to 48 months on marble, 36 to 60 months on granite and travertine, and indefinitely on quartzite in worktop use (though we still recommend a check at the three-year mark). Sealer is not a permanent state and will gradually wear through in traffic paths and around sinks, which is why re-sealing is part of the ownership cycle rather than a one-off event.

When sealing is not enough on its own

If your stone already has visible staining, sealing will not remove it. Existing stains need stain and etch removal first, then sealing. Similarly, if the stone is dull, etched or worn, sealing will protect it in its current state, not restore it. Those cases need polishing, honing or deep cleaning first, with sealing as the final stage. Sealing is never the first step in a restoration. It is always the last.

Why choose us for stone sealing

Sealer choice is where most professional stone maintenance in London goes wrong. Generic "stone sealer" off a merchant shelf is almost never the right specification. A Calacatta marble bathroom wall does not need the same product as a Jerusalem limestone hallway, which does not need the same product as a sandstone patio. The porosity test we run at the start of every job tells us which one to use, at what concentration, and for how many coats. Marius is on every sealing visit, we never seal over dirt, old wax, failed previous sealer or damp stone, and every sealer choice comes with a written note explaining why that specific product was used. We are fully insured for residential, heritage and commercial work, with documentation on request.

Areas we cover

We seal natural stone across central and north London, including Mayfair, Kensington, Chelsea, Holland Park, Notting Hill, Belgravia, Hampstead, St John's Wood, Marylebone, Primrose Hill, Islington and Bloomsbury, plus selected projects in the Home Counties. See areas we cover for the full list.