The official Oamaru Stone guide to preparation, resealing, waterproofing, and maintenance
Oamaru Stone has a magic trick that means buildings made from it stand the test of time exceptionally well. Take a stroll through Oamaru’s Victorian quarter, and you’ll see magnificent buildings over 150 years old. The reason is that limestone creates its own protective coat as soon as it is exposed to air. Then, without cleaning and maintenance, it will age gracefully like the Victorian buildings, but if you want your Oamaru Stone to keep its fresh, newly quarried appearance, a little regular TLC is necessary.
You might have a new build that incorporates elements made of Oamaru Stone, or it could be a building with a few years under its belt. Depending on its age, the TLC process varies slightly. So first we’ll take a look at the cleaning and maintenance of existing buildings, and then consider how to prepare new builds for a lifetime of looking beautiful.
Resealing and maintenance of existing Oamaru Stone buildings
If the job has been done properly, you can expect the water sealing your Oamaru Stone to last up to ten years. But it pays to check annually that the water repellent seal is still working – simply by spraying a little water onto the surface. If all is well, the spray will concentrate into small droplets on the stone’s surface.
However, if the surface is porous due to the water repellent coating wearing out, the water will be absorbed, turning the stone slightly darker.
The worst enemy of Oamaru Stone is moss, mould and lichen, and if you spot any of that, you need to get onto it immediately with a herbicide, even if the stone can’t be sealed until summer.
To clean Oamaru Stone, apply undiluted Jasol Hypostat mixed with Kemsol Moss Kill at a ratio of 50:1 using a knapsack sprayer. Leave the treatment to react with the organic growth for around three days, then wash it off with a garden hose, lightly scrubbing any problem areas where required.
Repeat the process until you are satisfied with the result. The sun is your ally when cleaning Oamaru Stone, as it helps to naturally bleach the stone, so hot, dry weather will give the best results. Badly stained stone may require several applications before it is fully clean.
If you’re unsure how much product you’ll need, contact the quarry and we can help work out how much cleaning product and sealer you will need for your project.
Once the stone is clean and completely dry, replace any loose pointing before applying Aquellux S water repellent sealer.
Aquellux S is a siloxane water repellent that is a highly effective sealer for porous building materials that won’t change their appearance. We highly recommend using Aquellux S on all Oamaru stone structures – both new and existing.
Warning: Your pressure washer or water blaster should not go anywhere near Oamaru Stone. The water jet will make a horrible mess of the surface, and loosen or even destroy the pointing.
Preparation and waterproofing new Oamaru Stone buildings
When your new building is finished, the final step is preparing the exposed Oamaru Stone for its Aquellux S sealer.
Start by washing all the surfaces. Treat anywhere you see moss or mould with a herbicide. When the surface is completely dry, apply your Aquallux S. Because Oamaru Stone is more absorbent than concrete, you’ll need to apply it at a higher rate – we suggest using 1 litre per 1-1.5 m2.
And that’s it! If it’s been done properly, your Oamaru Stone surfaces should be water-resistant for up to 10 years.
The enduring beauty of Oamaru Stone
It doesn’t take much to keep the rich honey tones of your Oamaru Stone looking clean and fresh. And it’s worth taking care of it, because if Oamaru’s Victorian quarter is anything to go by, your building will still be standing proudly and giving pleasure to people in 150 + years from now.
If you’re inspired by the possibilities of working with Oamaru Stone for your next building project, give us a call today on 03 433 1134 or email sales@oamarustone.co.nz