Sandstone cleaning and sealing in Bondi

Sandstone in Bondi works hard for its size. Low front fences take salt from the sea air and splash from passing traffic on Bondi Road. Entry steps to apartment blocks take heavy foot traffic, bin wheels and spilled drinks from the weekend before. The bases of older Victorian and Inter-War buildings show efflorescence where moisture moves through them. Many of these surfaces have been pressure-washed in the past, often by whoever was available, which leaves a roughened face that catches dirt faster and goes black sooner. The result is stone that looks worse a year after each clean than it did before, which is the cycle we aim to break.

Our technicians identify what is on the stone before choosing a cleaner. Salt and traffic grime get a matched detergent and a low-pressure rinse. Mould and algae on shaded walls are treated with a biocide and left to dwell. Efflorescence is brushed off dry, treated, and the likely moisture source noted for the building's manager. All run-off is bunded and vacuumed up, so nothing is left on the footpath or in the gutter, which on a busy street also keeps pedestrians safe. We work in sections on shared entries so residents can always get in and out, and mark any wet or recently sealed areas clearly with signs.

Sealing is usually worthwhile on Bondi entry steps, paths and fence caps. A breathable penetrating sealer slows the uptake of salt, spills and grime, so routine cleaning by building staff actually works and the stone stays lighter for longer. Building bases that are drawing moisture up from below are a different case: there we would rather fix drainage and leave the stone open, because sealing can trap salts. We record the product and areas sealed, which helps strata managers plan the next round of maintenance and explain it to owners. A yearly water-drop test on the busiest steps shows when protection is starting to wear.