Looking after Ōamaru Stone

Cleaning new (exterior) Ōamaru Stone

Cleaning isn’t usually required to safeguard the durability of Ōamaru Stone, but an annual wash with a soft brush keeps the limestone looking its best. You can do this yourself if you wish.

Sealing Ōamaru Stone exterior cladding

Depending on the sealing product you choose, Ōamaru Stone cladding requires resealing every seven to twelve years.

When first built/installed, Ōamaru Stone should be washed down, brushed clean and any areas which have discoloured with moss or mould should be treated with a moss/mould killer..

When the stone is dry, it can be treated with a water repellent sealer.

This treatment should be carried out as per manufacturer’s instructions. Keep in mind that Ōamaru Stone has a greater absorbance rate than concrete.

How to Reseal Ōamaru Stone

To check if Ōamaru Stone limestone needs resealing, spray water onto the surface. If the water repellent is working, water will run into droplets on the stone’s surface. If the surface is porous, water will be absorbed into the stone, which will go slightly darker in colour.

A general indication of the stone requiring treatment, is when mould, moss or lichen begins growing on surface, causing green or greyish discolouration.

To clean Ōamaru Stone, a moss or mould killer should be applied by thoroughly wetting the surface with product.

When the moss/mould killer has taken effect, clean with a hard bristled brush. In some areas where there is a build-up of moss or mould, a wire brush may be required. Do not clean the stone with a high-pressure spray, as this can loosen pointing and damage the stone’s surface.

Ōamaru Stone should then be left to dry, then a second application of moss/mould killer applied.

Any repairs required (e.g. loose pointing) can and should be carried out at this stage.

When the stone has completely dried out, apply water repellent sealer.