My son is having a new wood burning stove in his lounge and chose some sandstone as the new hearth. This more or less matches some stonework in the garden, so it looks like a good choice.
It is in smooth sheets , which have been fitted and some slight bows sanded out to give a smooth surface at the joins. As delivered the sandstone had one or two small surface marks and a couple of small blackish discolourations. Sanding with very fine wet and dry appeared to remove these.
The first coat of sealant, which I believe is "Thompson's Sandstone Seal" has been applied. When wet the sandstone was a lovely deeper orange-red, but has dried patchily, and the small black areas are showing and also a small 1" -ish place where the sealer has drawn a white discolouration to the surface.
He also has an unopened tin of "Lithofin MN Stain Stop", which says on the tin that it is "invisible".
Are there any suggestions for the best coating to apply to seal the stone and make the deeper redder colour permanent? Also, he will sand away the white (presumably salts that the sealer has brought to the surface) and black patches, but we would prefer any further coating not to draw
out any more salts or whatever.