Sandstone cleaning and sealing in Centennial Park

Sandstone on a Centennial Park property is usually some of the original 1905 to 1925 fabric: front fences and gate piers, wide entry steps, garden walls and edging, and occasionally whole facades. Under the parkland canopy, three marks dominate. Brown tannin shadows from wet leaves and bark, black and green growth on shaded faces, and spotty etching under trees where birds roost. Some houses also have old repairs or painted sections. We photograph and test each element before quoting, so you can see what the stone looks like after each method on a small patch rather than relying on our description.

Tannin stains are lifted with a mild oxidising cleaner suited to sandstone, and deeper shadows are drawn out with a poultice that sits for a day or two. Lichen and mould receive a biocide that stays on for as long as it needs, and the residue is then washed off with lukewarm water at a soft setting. Bird marks respond to a mild cleaner and careful brushing. Our technicians never put a narrow high-pressure jet on this stone; it would cut into the face and leave stripes. Lawns and beds are covered, and every bit of wash water is caught and vacuumed, so nothing runs down the drive to the street drains.

Sealing helps most on the steps, paths and terrace paving that collect leaves, because a breathable impregnator stops tannin soaking deep and makes regular blowing and an occasional wash enough. Facades, gate piers and freestanding walls are usually better left breathing, with sealer kept to their caps where water sits. You see natural and enhancing samples side by side before deciding. For houses in the Lang Road conservation area, talk to the City of Sydney before a sealer that changes the stone's colour. We record what was used and where, and suggest a water-drop test on the paving every couple of years.