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Posted: Thu Sep 28, 2017 3:59 pm
by Whitefusion
Hello I Have just had my patio laid and the stones are dirty after being laid, how does one clean these.
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The rain makes them black but they still appear dirty have not tried anything yet, the joints were filled with a Wide Joint Filler.
Many thanks
Posted: Sat Sep 30, 2017 8:17 am
by Old Codger
Whitefusion wrote:Hello I Have just had my patio laid and the stones are dirty after being laid, how does one clean these.
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The rain makes them black but they still appear dirty have not tried anything yet, the joints were filled with a Wide Joint Filler.
Many thanks
You have to be careful with Limestone as you cannot use acid cleaners. Lithofin Power Clean with a lot of scrubbing should work ok
Posted: Wed Oct 04, 2017 9:40 am
by blacklimestoneproblem
A non bio washing powder (general purpose cleaner with surfactants which helps get into the surface whilst also holding substances in suspension) is also highly alkaline which is what Lithofin Power Clean is without the surfactant, its basic GCSE chemistry using acid's and alkaline's to alter other chemical reactions (& sometimes time, heat & pressure like diamonds) that has taken place. Its a pity most teacher's cant explain what they are teaching people, and what it can be used for.
Likewise if you want some hard work, use a stiff brush, the end of the bristle's dont make that much contact with the surface unlike say a electric rotary cleaner with a black scrubbing pad. Personally I've found the latter with just water to be more effective as its effectively grinding off the top surface which is why you can see a dull grey paste coming off the slabs when using the scrubber. Its good for riven slabs as this helps smooth the edge's of the stone which is important if the patio is to be used barefooted as it reduces the chance of cuts to the feet. It also accelerates the wear of the stone so it ends up smooth in place's if you use the electrical rotary cleaner for long enough. If you got an electrical rotary cleaner with a container to hold liquid cleaner's, just fill this up with water and have the handle at an angle close to the vertical to get extra weight and thus grinding power into the stone which can also reduce the amount of time spent on each slab.
Something like this https://www.hss.com/hire/p/floor-scrubber-polisher-110v with the black pad like this http://www.onestopcleaningshop.co.uk/box-of-....ds.html
will bring even several years old faded black limestone back to its original colour.
If you spend lots of time on each slab, you will smooth/grind them flat so they are almost polished, so dont spend too much time on each slab if you want to keep some of the riven look. Either way it's probably the fastest way to bring these black limestone slabs back to an appealing look & colour whatever their condition whilst eliminating any sharp edge's especially as you can get odd corners sticking up more than the surrounding slabs. Think of it as accelerating the wear that would naturally occur on them where there is high footfall.
Whether you decide to use the scrubber's with just water or a pinch of washing powder per slap, hose down each slab as you go along so the resulting paste/foam doesnt stick to the top surface and inspect each slab as you go along. You'll get to see even when they are wet the lighter parts of a slab which needs more time with the scrubber going over them. Slow movement's no fast left to right movements and dont leave the scrubber in any one area so it smooths the stone flat, although on the stone's I've done here, that would probably take a good hour per slab to give you an idea of time taken to smooth to a polished finish.
Controlling these scrubbers is a bit like flying a helicopter, once you get the balance right so they can spin on the spot, to get into slabs with natural dip's, angle the scrubber so one edge has all the weight on it and its best to use smaller diameter cleaner's as this will follow the contour of the slabs better. When angling the scrubber dont be surprised if the motor's complain about it with some weird noises, as you are putting more drag on the motor, but you want a scrubber with a high torque low speed motor for best effects, fast spinning motor's are more likely to polish. Something like a 15" diameter is probably the biggest you want.
Afterward's its up to you whether you seal them or let them weather naturally, bearing in mind, if you do opt to weather them, there is nothing stopping you from going over the slabs in a couple years time repeating the process to bring them back to their natural "underground" colour again, but each time you do this you will get closer to polished slabs.
If anything this should be a process for all riven slabs as it reduces the chance of kids running around on patio's from catching the odd corner sticking up which can then trip them up or from cutting feet when running or walking barefoot across a patio with sharp edges. The builders/ground works experts will typically use glove's to lay them to avoid cutting their hand's so it seem's logical to use these scrubbers to help smooth off the sharp edge's & uneven corners.