Sandstone cleaning and sealing in Bondi Beach

On an Art Deco block a street or two back from Campbell Parade, the sandstone tells a consistent story. The fence cap facing the ocean is rough and slightly sugary where salt has been crystallising in the pores. The entry steps carry a grey band of grime down the middle and sand packed into the joints. The side path, tucked between two buildings, is green and slick. Each condition needs its own treatment, so our technicians test a small patch of each before the strata receives a quote, and the scope we send lists the surfaces separately with photographs. That makes it easier for a committee to approve stages if the budget needs splitting.

We start dry. Loose salt and sand are brushed and vacuumed off before any water touches the stone, so they are not driven deeper into it. Grimy steps get a sandstone-safe detergent and soft rotary brushing, followed by a low-pressure or controlled hot-water rinse. Algae on shaded paths is killed with a biocide that stays on long enough to reach the root. No turbo nozzle is used, because salt-softened sandstone erodes fast under a jet. Wash water is contained with mats and bunds on the footpath side, then vacuumed up, so nothing reaches the gutters that drain toward the beach a few hundred metres away.

After a clean, the busiest surfaces are where sealing earns its cost: entry steps, paths and fence caps that take salt, sand and spills every day. A breathable penetrating sealer slows how fast salty water enters the stone and makes weekly cleaning by building staff far more effective. We keep sealer off walls that hold back soil or draw moisture up from the ground, because trapping that moisture would push salt damage deeper. The committee sees sample patches before deciding, and we record the product and areas in writing. Beach-side stone is worth a water-drop test each spring, since protection tends to wear faster here than in sheltered suburbs.