After grouting, wait until the floor is completely dry. Then, make a light and dry sandpapering of the floor using a machine with 90-grit sandpaper for removing defects in laying and an oxidation. After this initial sanding, go on with washing with buffered acid to remove efflorescences and then rinse with water only. After one week at least, and with completely dry floor, proceed with laying of two coats of raw linseed oil and one coat of paste wax. Then, remove with a felt the excess wax on the surface and lay a coat of liquid wax for maintenance. After 2 or 3 days the floor is perfectly walkable. For maintenance, after normal cleaning with detergent and water, apply a coat of liquid wax diluted. This should be done only if required to prevent stratification of wax.