I'm having difficulty cleaning the grout residue from the face of the tiles (which have a matt surface). Is this possibly because I've left the grout to dry for too long before cleaning? Have tried an acid based cleaner but this has taken the colour out of the grout so it's now much paler. Still got patches of grout on tiles. Can anybody suggest a good cleaner that wont damage grout further?
Hope you can help as the tiles dont look entirely clean. Thanks

If you register you'll get more of a response, in the meantime a few more details would help, what tile type have you got, colour and make of grout as well, some pictures as well if you could.

I've just registered now. The tiles are V & B Bernina and grout is by Mapei in the colour Jasmine ( pale beige/cream)
Sorry no pictures but I've been left with patches of grout haze on the face of the tiles. Tried using H G Tiles, cement grout film remover (3 times) but it hasn't removed it all and seems to be affecting the colour of the grout which is becoming lighter.

You have definately left the grout on too long. Mapie Ultracolor Plus dries very hard even though it is a flexible grout and, as you have found out, is very difficult to remove once cured. Try Lithofin cement residue remove.

Thanks for your reply I'll try the Lithofin Cement residue remover. Just got some small patches left now so hopefully it will do the trick. For future, how big an area can you grout before cleaning off or how long can you safely wait before cleaning?