The before and after photograph below is from a job we did in a Shower Cubicle tiled with small square Mosaic tiles at a house in Bedford. As you can see from the photograph the grout had become stained with mould and mildew growth which had become quite bad and moved onto the surface of the tile.
Cleaning Mosaic Tiles
To resolve the problem a strong dilution of Tile Doctor Pro-Clean was scrubbed into the tile and grout by hand using a stiff brush. It’s best to let the Pro-Clean soak into the tile and grout for ten minutes before working in and to help the solution stick on vertical surfaces it’s best to decant the Pro-Clean into a spray bottle and spray it onto the surface of the tile, this allows it to mix with air making it lighter and enabling it to stick to the surface instead of running off.
The mould and mildew had become quite ingrained and had managed to get quite a foothold in the grout which due to its cementitious nature is actually porous near the surface. As a result the tiles were proving very had to get clean and so working in sections the process was repeated numerous times requiring a lot of physical effort and Pro-Clean before we were happy with the results.
Source: Residential and Commercial Stone, Tile and Grout Cleaning Services in Bedfordshire