Dirty tile grouting

[news.btinternet.com]

Hi, I have bought a house and the grout between the tiles (white on the wall) and on the floor is very dirty (nearly black in some places).

That is the best approach to cleaning this. Do I need to rake out the grout? If so, what is the best tool or technique? Will a wire brish attached to a drill wreck the til surface?

Or is there a chemical treatment that will work?

Thanks

[The3rd Earl Of Derby]

Tooth brush and Domestos diluted bleach.

-- Sir Benjamin Middlethwaite

[Douglas de Lacey]

Are you in a hard water area? If so, the dirt will be embedded in scale: start with a mild acid spray (I use citric). Douglas de Lacey

[david lang]

The off the shelf grout stain removers in the supermarkets work well. They are 'acitvated' bleach based e.g. more effective than standard bleach. That a nail brush and some elbow grease.

[news.btinternet.com]

Where do you get this acid spray?

[R.P.McMurphy]

[Douglas de Lacey]

I bought the acid from a manufacturing chemist (JM Loveridge). I think the spray device originally held Windolene. The citric acid is useful for all sorts of other things, like getting sweat stains out of clothes (uk.d-i-y thread of many years ago). Douglas de Lacey

[meow2222]

but doesnt stick that well to dried gunk.

Once youve done, brushing it with dry lime whitens it further.

If you get it properly clean, or redo it, I'd apply waterproof varnish to it. This makes it easier to clean and get less ditty, since youve then got a smooth gloss surface instead of a semi-rough cement finish.

NT