Hi,

I have laid some natural slate tiles as a hearth. They were bedded on 
standard mortar and grouted normally. I then treated them with HG porous 
stone sealer.

The problem is most of them have now exuded some white powder which 
smells salty. It also is ompossible to get rid of. I scrub and wash it 
off but it just returns.  HELP PLEASE !

My hearth looks awful, anyone know what to do.
Thanks Stu

"Stuart"  wrote in message 
news:nPudnTCyiN3I0K3eRVnytw@pipex.net...

> Hi,
>
> I have laid some natural slate tiles as a hearth. They were bedded on 
> standard mortar and grouted normally. I then treated them with HG porous 
> stone sealer.
>
> The problem is most of them have now exuded some white powder which smells 
> salty. It also is ompossible to get rid of. I scrub and wash it off but it 
> just returns.  HELP PLEASE !
>
> My hearth looks awful, anyone know what to do.
> Thanks Stu


I wonder whether the white powder is encrustations of salts brought up by 
water seeping through the slate and evaporating - a bit like a stalagmite. I 
suspect they would dissolve with a weak acid, vinegar for example, or some 
product for removing deposits on taps, but would come back. If this is 
what's happening, then lifting the tiles and fitting a DPC before re-laying 
them would solve it.

Rob Graham