I have have had a set of steps built in my garden with buff coloured sandstone treads. The risers have been rendered as have the walls either side of the steps.
The render used was K-rend in polar white. Unfortunately where the render has spilled onto the sandstone it has left a white stain. It is not clear how deep this stain has penetrated but it is certainly not just excess render on the surface.
I am reluctant to use an acid, such as brick acid, as I understand that this can react with the iron in the sandstone and produce another type of staining. I am also reluctant to use a jet power washer as it is not clear that it would work and I could damage the render.
Other than using sandpaper to remove the stained surface layer, does anyone know of a way of removing the stains from the sandstone?
The render used was K-rend in polar white. Unfortunately where the render has spilled onto the sandstone it has left a white stain. It is not clear how deep this stain has penetrated but it is certainly not just excess render on the surface.
I am reluctant to use an acid, such as brick acid, as I understand that this can react with the iron in the sandstone and produce another type of staining. I am also reluctant to use a jet power washer as it is not clear that it would work and I could damage the render.
Other than using sandpaper to remove the stained surface layer, does anyone know of a way of removing the stains from the sandstone?