This Grout ink formula is water based and covers over stained areas that are caused by everyday mould and dirt build up on grout between tiles. Not only does this product restore the grout"s look it also helps prevent further moulding with its anti-bacterial formulation.Product Specifications5mm bullet nib reversible.Water based & non - toxic.Anti - bacterial & anti - fungal formula.Safe to use in enclosed areas.Covers 40 metres of grout area.Water resistant.Valve activated to control ink flow.For use on all types of wall & floor grout.