I have a problem with grout staining on some slate tiles which have been laid around a swimming pool. The tiles were sealed, this has been removed and we have tried to remove the grout stains with a acid wash.
Does anybody no of a stronger product which might do the trick.
Thanks

Hi mark.

Don't use acid on stone unless you know what you are doing, You will now need to neutralize the acid or it will continue to etch into the slate and over time will turn it into slurry. To do this get yourself a big box of bi-carb soda and mix a coulpe of handfuls in 10lt of water and rinse this over the stone liberally and allow to stand for 10 min then hose of with clean water.

You are better off using an alkaline cleaner on stone if you aren't experienced, pool chlorine would work well. Dilute 50/50 with water and whilst wearing gloves scrub the tiles and grout, then wash with clean water.

what type of slate is it?

Thanks for the replies, I think the slate is called Basalt with a flame finish and was supplied by Stonell.
It is very hard, we have washed the acid off. The acid we used was called spring clean, it seemed to have little or no effect.
Thanks for the help.

Basalt stone can be re-traced to volcanic origins, so it is categorized as a lavatic stone. Its unique structure and its remarkable uniformity are a result of the gases that escape during the cooling process. It really really hates acid of any kind.

Thanks for the help, we'll try the chlorine and see what happens.I can get hold of liquid chloine(sodium hyphochlorite) would this be ok.
Once again thanks for the help.

Originally Posted by Unregistered

I have a problem with grout staining on some slate tiles which have been laid around a swimming pool. The tiles were sealed, this has been removed and we have tried to remove the grout stains with a acid wash.
Does anybody no of a stronger product which might do the trick.
Thanks

I am confused with this post Do you have slate or Basalt? They are easy enough to tell apart! Maybe you could post some pictures then we can advise you the best route to remove the Grout Haze?

Kev

The stone is called Stonell Basalt, I will try and get some pics done once the rain stops.
Thanks