Natural stone maintenance is the combination of cleaning, protecting and light repair that keeps stone looking good and structurally sound. The heart of the craft is that every stone type reacts differently: what saves marble can ruin granite’s finish, and the other way round.
First question: is it calcareous?
This distinction drives almost every decision.
- Calcareous stones — marble, limestone, travertine and Belgian bluestone. These are attacked by acid. Vinegar, citric acid, descaler, cement film remover and many bathroom cleaners eat away the polish and leave dull patches
- Silicate-bound stones — granite, quartzite, slate and most sandstones. These tolerate acid better but are more sensitive to strongly alkaline products and, in some cases, to oil staining
When in doubt: test every product on an inconspicuous area first, and always rinse off.
Cleaning
- Indoors, routinely: dust and mop with clean water or a pH-neutral stone cleaner. Avoid soap-based general cleaners — the film they leave holds dirt
- Outdoors: brush with water and a soft brush. A pressure washer can permanently damage soft stone, weathered sandstone and above all the joints; if used at all, work at low pressure with a fan nozzle and a generous stand-off
- Green growth responds to a proprietary algae and moss remover; let it work and do not rinse immediately
- Rust and oil stains need a poultice that draws the stain out of the stone. Grinding usually makes it worse
Protecting
- Impregnating (water-repellent treatment) leaves the stone breathable while repelling water and dirt. It is the standard protection for worktops, floors and facades. The effect wears off: reapply every few years on heavily used surfaces, and at longer intervals on facades
- Film-forming coatings are almost always a mistake on facades: moisture stays behind the film, and frost then causes spalling
- Wax or oil suits an oiled slate or sandstone floor, not polished marble
Points to watch
- De-icing salt is the biggest enemy of bluestone thresholds and steps. Use grit or sand instead
- Never start a facade clean without trials. Ask for several test patches of around half a square metre
- Repoint before cleaning, not after; otherwise you flush water into the construction
- North-facing walls green up faster because they stay wet longer. More frequent cleaning helps there more than a harsher product
Related terms
- Bluestone
- Marble
- Granite
- Limestone
- Hydrophobizing
- Natural stone finishes
- Natural stone replacement
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