Sandstone cleaning and sealing in Fairlight

Walk down a typical Fairlight block and the sandstone changes as you go. Up near Sydney Road and Balgowlah Road, front walls collect traffic grime and the grey film that builds on any stone beside a busy street. Midway down, retaining walls and side paths sit in the shadow of neighbouring buildings, and that is where black mould, moss in the joints and green algae take hold. Closer to Fairlight Beach, terraces and coping carry a gritty salt residue from the harbour air. Our technicians test the cleaner on each of these zones separately, because a mix strong enough for a mouldy wall can be more than a sound terrace needs.

The cleaning itself is patient rather than forceful. Mould and algae are dosed with a stone-safe biocide, and we give it time to kill the growth right down into the pores before brushing and rinsing at low pressure with a wide fan. We never use a turbo tip, which cuts into sandstone and leaves a furrowed face. Salt crusts come off with a dry brush first, so we are not simply pushing dissolved salt deeper. On walls that weep groundwater, we point out where water is coming through, because no clean lasts long on a face that never dries. Every landing has its own containment, and the recovered water leaves with us rather than heading down the hill.

Sealing on a harbour slope is selective. Terraces, stair treads and coping that take foot traffic and salt tend to suit a breathable penetrating sealer; it keeps water and grime out of the pores while letting vapour escape. Retaining walls holding back wet soil are generally left unsealed, since sealing the face of a wall that is pushing moisture outward traps salt behind it and speeds up flaking. We wait until treated stone has dried properly, which on a shaded Fairlight slope can take several fine days, and we lay natural and colour-enhancing test patches side by side for you to compare. The product and date are recorded for your records.