Tile grouting

[daftwit]

my bathroom tiles (shower cublicle) are those lovely small coloured glass mosaic ones. However, they are looking really dull and the grouting has turned yellowish in places, with mould/black areas in others- how can i get them back to the gleaming white grout i once had ???

[Furball]

I always use bleach to wipe each grout part over.

Leave for about an hour then shower off. Mine come up like new