HG cement, mortar & efflorescence remover (limex) (HG product 12) removes stubborn cement and mortar residues from all types of porous and non-porous tiles, flagstones and non-calciferous natural stone types such as Norwegian slate, granite and quartzite. Dissolve half a litre in 5 litres of water. First wet the surface with clean water and then apply the solution using a floor cloth or mop. Then scrub the surface well with a stiff broom or scrubbing brush. Leave to penetrate for a few minutes and then scrub again. Then remove the solution from the surface with a mop, and mop the floor using clean water.