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