Attempting to apply fresh grout directly over existing old grout without proper mechanical removal is a shortcut that almost always leads to premature failure. Because old grout joints accumulate microscopic layers of grease, soap scum, hard water minerals, and dirt over time, a new layer of grout cannot form a permanent mechanical bond with the old material. Within a short time, the thin veneer of new grout will crack, flake, and detach completely from the joints. Professional installation standards dictate that you must remove the deteriorated top layer of old grout using a grout saw or multi-tool to create adequate depth for the new grout to lock securely into place.
1 votes
Marked as accepted