Sealing used quarry tiles.

[stagbeetle]

I have recently had some used quarry tiles laid to create a fireplace hearth. They are porous and therefore require sealing to protect them from accidental spills or wet cup marks etc.
The sealers I have seen advertised seem to be aimed at kitchen or hall use where the tiles would be subjected to heavier wear.
Can anyone recommend something which is more readily available.

Also some of the tiles have holes in them which look like they may have been air bubbles at the time of manufacture? (approx. 5 - 8 mm deep by the same wide) Could these and other blemishes be filled with something other than cement to make a feature ofthem?

Many thanks in advance for advice.