HG tile cement, mortar & efflorescence remover (product 12) removes stubborn cement and mortar residue from all types of porous and non-porous tiles and flagstone, but also from non-calciferous natural-stone types, such as Norwegian slate, granite and quartzite. The unique aspect of this product is that it dissolves cement from the tile surface but not the cement from the grouting. It even strengthens the grouting.
Dissolve half a litre of HG tile cement, mortar & efflorescence remover in a bucket with 5 litres of water. First clean the surface that requires treatment with clean water. Then apply the solution liberally with a mop or floor cloth. Then scrub the surface well with a stiff broom or scrubbing brush. Leave to work for a few minutes and then mop the floor properly with clean water.