Over a period of time, the grout between ceramic tiles become stained and dirty especially where a lot of water comes into contact with it, for example in kitchens, bathrooms and showers.
Remove the old grout with a regrouting tool. Remove two or three millimeters. Brush off all the dust from the tiles and the surfaces. Always wear rubber gloves before starting to grout. Spread the grout with your applicator making sure all the gaps are filled. Fill in any screw holes that are no longer required. After completing, wipe over with a damp sponge. And finally, wipe over with a limp-free cloth. It’s always advisable to seal the tiles where they meet with work surfaces. Apply a length of masking tape along the surface three or four millimeters away from the wall masking off any returns. Put the tape onto the vertical face of the tile. Again, three or four millimeters away from the work surfaces. Once the entire area has been masked off, run a bit of silicon between the two pieces of tape. Run a damp plastic spatula along the silicon side to form a V. Leave the silicon to form a skin then remove the masking tape then a neat perfect has now been achieved.