Some stones will be prone to bleed on the edge or surface contamination from the pigments or moisture ,these will need to be sealed prior to grouting.
Bleed is 5-10 mm into the stone edge the full depth, if the stone is not acidic resistant , these generally get taken up as the contamination is the full depth.
Biggest I have seen taken out due to this was 550 Sqm ( the face was sealed but not the edges), surface contamination can often be cleaned out or by re surfacing dependant on finish.
Sealing after grouting ensures water and oil reppelance to the grout and will ease maintaining the surface
Bleed is 5-10 mm into the stone edge the full depth, if the stone is not acidic resistant , these generally get taken up as the contamination is the full depth.
Biggest I have seen taken out due to this was 550 Sqm ( the face was sealed but not the edges), surface contamination can often be cleaned out or by re surfacing dependant on finish.
Sealing after grouting ensures water and oil reppelance to the grout and will ease maintaining the surface
