Grouting Porcelain Tile
Wipe down the tiles and shape the joints while the grout is still wet and soft.
Porcelain tiles absorb water very slowly, which allows grout to set up on the face of the tile while it’s still soft in the grout joints. If you wait for the joints to set up, as you would with regular ceramic tile, the grout dries on the porcelain and is difficult to clean off. Therefore, you must wipe down porcelain tiles and shape the joints while the grout is still wet and soft 1. This requires a deft touch. First, wait for 10 minutes to 20 minutes, then shape the joints very carefully, wiping and cleaning the surface with great care 2. The grout will take much longer to cure in porcelain tile than standard tile, and in some rare situations, you may see some efflorescence, which looks like a white powder atop the grout. Clean this off, as described in “Removing Efflorescence.”
Excerpted from Tiling Complete, 2nd Edition by Robin Nicholas and Michael Schweit.
Available in the Taunton Store and at Amazon.com.