Care & maintenance
Oamaru Stone buildings require maintenance, cleaning and sealing for the stone to retain its natural white / creamy colour. The following information may be of some assistance.
When built Oamaru Stone should be washed down, brushed clean and any areas which have discoloured with moss or mould should be treated with a moss or mould killer.
When stone is dry it should be treated with a top quality water repellent silicone sealer.
This treatment should be carried out as per manufacturers instructions, along with an exception that most water repellents require a cover of approximately 1 litre per 1 – 1.5 m2 on Oamaru Stone which has a greater absorbency than concrete.
In normal circumstances correctly treated surfaces remain water resistant for up to 10 years.
To check if stone needs resealing, spray water onto stone surface. If water repellent is working, water will run into droplets on stone surface. If surface is porous, water will be absorbed into stone which will go slightly darker in colour. A general indication of stone requiring treatment is when mould, moss or lichen begins growing on surface, causing green or greyish discolouration of the stone.
To clean stone a moss or mould killer should be applied by thoroughly wetting surface with product. When moss 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 stone with high pressure spray as this can loosen pointing and damage stone surface.
Stone should then be left to dry and a 2nd application of moss killer applied.
At this time any repairs required ( e.g. loose pointing ) should be carried out.
When stone has completely dried out, apply water repellent sealer.