Oxidisation in Natural Stone
Oxidisation is a natural phenomenon found on lighter coloured paving slabs, especially sawn and riven grey sandstone. It is more of a problem when it manifests on the surface as rusty coloured stains.
Many paving slabs, especially sandstones, have natural deposits of iron within its ‘pores’, which may brought to the surface by moisture through evaporation, which occurs naturally.
Paving laid on a non-full contact mortar bed, with even a few voids, which may fill with water via capillary action can, and will, increase the risk of oxidisation. Fortunately, there are rust removing products which can clear away all but the worst of the problem.
There is no solution to this problem, so avoid using any chemicals, especially acids, to the paving.
Naturally occurring iron stone can be seen on the surface of the stone, which can also lead to iron deposits leaching into surrounding paving.
