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Care & Maintenance

Ōamaru 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.

New buildings

  • When built, Ōamaru 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 the stone is dry, it should be treated with a top quality water repellent silicone sealer.
  • This treatment should be carried out as per manufacturer’s instructions, along with an exception that most water repellents require a cover of approximately 1 litre per 1 – 1.5 m2 on Ōamaru Stone, which has a greater absorbance than concrete.
  • In normal circumstances correctly treated surfaces remain water resistant for up to 10 years.

Building resealing

  • To check if the stone 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 stone, a moss or mould killer should be applied by thoroughly wetting the surface with product. When the 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 the stone with a high pressure spray, as this can loosen pointing and damage the stone’s 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 the stone has completely dried out, apply water repellent sealer.