This Ceramic tiled family bathroom with shower was installed at house in Leighton Buzzard and was in need of rejuvenation. You can see from the photograph below that the tiles were in reasonable condition but the grout had become ingrained with dirt which is not unknown as the top layer of grout is porous and will discolour over time if not protected.
Cleaning Ceramic Tile and Grout
The Ceramic tiles and grout were treated using a strong 2:1 dilution of Tile Doctor Pro-Clean mixed 50/50 with Nanotech Ultraclean which combines a highly powerful Tile and Grout cleaning product with tiny abrasive particles. For vertical tiled surfaces I recommend the mixture is decanted into a bottle with a trigger spray attachment which when sprayed onto the wall allows the cleaner to mix with air making it lighter and allowing it to stick better. The solution was then worked in using a stiff scrubbing brush by hand before being rinsed off with water; this process was repeated a number of times until we had managed to clean all the areas and then left to dry.
The grout was dried and the sealed with a couple of coats of Tile Doctor Grout Sealer which forms a protective barrier over the porous grout and keeps it looking good for longer. Most sealers can be used on grout (check the label to confirm) but for best results use a spray bottle as mixing the sealer with air improves its ability to stick to a vertical surface.
Source: Ceramic Tile and Grout cleaning tips