Be sure to rinse the tiles after and avoid using any paper or cloth-based products to wipe as this will . HG grout cleaner removes stubborn dirt from grout in floors and walls in, for example, the bathroom, toilet or kitchen. Apply it to the grout and leave for 15 minutes, then take an old brush and scrub the paste away. Cleaning your grout is a chore we all try to avoid; it’s stubborn, grimy and often a big task to undertake. Step 1 Make a paste from two parts bicarbonate of soda to one part water, then rub onto dirty grout using an old toothbrush.