Natural limestone is soft. It gets cleaned at low pressure, or it gets damaged.
Getting this wrong is the most common way limestone gets wrecked.
Limestone stains, and the staining is underneath the growth. If a wall has been black and green for a long time, expect to find discolouration and staining once that comes off. The growth is what's cleaned away; the marking left in the stone from years of it sitting there is a different thing, and it doesn't all lift.
Cleaning takes off the growth and dirt. Sealing is what protects the surface and slows it coming back.
An unsealed surface drinks water in. It holds that moisture down in the pores and stays damp after the top looks dry — and that damp is exactly what the mould and algae feed on. Sealing fills the pores, so less water goes in and the surface dries out faster. The black takes longer to come back and doesn't get as bad when it does, and spills sit on top instead of soaking in, so you have a real chance at preventing severe stains.
It is not a magic coating that keeps the surface perfectly clean. It still needs washing — it just needs it less often, and it's easier to clean in the future.
I seal the same day I clean. It is an additional service that complements the cleaning.
Why can't limestone be high-pressure cleaned?
Because the stone is softer than the water pressure. High pressure erodes the face and leaves visible lance marks. It's the one surface where the wrong method causes damage you can't undo.
Will cleaning make it whiter?
It'll come back to the colour the stone actually is — which, if it's been green and black for years, may include staining underneath that the growth was hiding. Clean, yes. Whiter than the stone, no. Anyone promising a brand-new look on weathered limestone is overselling it.
Can limestone be sealed?
Yes, and on limestone it's genuinely useful, because sealing the pores is what slows the green coming back. It's a separate job from the cleaning and quoted that way. Whether it suits your wall is worth talking through.
My limestone wall is crumbling — can you clean it?
I can clean it, but I'll tell you first that it'll still be crumbling afterwards. Blown limestone is a stonework problem, not a cleaning one.
How do I tell natural from liquid limestone?
Natural limestone is cut blocks or slabs with the grain and shell of real stone. Liquid limestone was poured and finished on site, in one continuous surface with control joints cut into it. If you're not sure, tell me on the phone and we'll work it out.
Call me now to find out more or book a quote — 0410 952 300
If your job is urgent, call me now on 0410 952 300
