Sandstone, cleaned and sealed, not polished.
Sandstone is soft, open-grained and thirsty, and most of it in Sydney is outdoors. That makes it a cleaning and sealing surface rather than a restoration one, and being straight about the difference is most of the job.
Sandstone is the stone Sydney is built from and built on: grains of sand bound by silica and clay, soft enough to carve and porous enough to drink. Indoors it turns up as feature walls, hearths and the occasional floor. Outdoors it is everywhere, as paving, steps, pool surrounds, retaining walls and the fabric of half the older buildings in the city. The texture is part of the material and part of the point, particularly outside, where a sawn or bush-hammered face is what stops it being slippery.
Outdoor sandstone gets biological before it gets dirty. Algae, lichen and moss take hold in the pores and hold moisture against the stone. Pollution leaves a black crust on sheltered faces. Leaf litter and soil stain it, and rising damp carries salts up through it that crystallise under the surface and push the face off in flakes, which is called spalling and is the one failure that is not cosmetic.
The work starts with the gentlest method that will actually shift the soiling, because sandstone is soft enough to be damaged by a pressure washer held too close or a chemical that is too strong. That usually means a low-pressure clean with a biocide given time to work, rather than blasting. Once it is clean and dry, an impregnating sealer slows the next round of absorption without putting a film on the surface, which would trap moisture in a stone that needs to breathe.
Where the limit sits, and it matters here more than anywhere else on this site: sandstone is not honed and polished back the way marble is. There is no polish in it to recover, and grinding the face off a textured paver makes it slippery and wrong. Stone that is spalling, delaminating or structurally cracked belongs to a stonemason, not to us. What we can honestly offer sandstone is a careful clean and a sealer.
Questions about sandstone.
What causes water marks on marble, and do they come out?
Water marks on marble are usually one of two things, and both come out. Around a basin or on a shower ledge, a white ring or haze is mineral deposit from hard water evaporating, which strips off. A dull ring where a wet glass or bottle sat is etching, where the acidity of what was in the glass has dulled the polish, and that is honed and re-polished. The two look similar and are handled differently, so a photo helps us tell you which you have. Neither is a reason to replace the stone. Hard-water marks come off with a mild descaling pass and a stone-safe pad, because the deposit sits on top rather than in the pores. Etching is the opposite: nothing was added, a thin layer of polish was dissolved away, so it is corrected with fine abrasives until the finish is even. Wet the mark with a finger: a mineral deposit vanishes and returns as it dries, while etching looks the same wet or dry.
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