Grind out the grout
Renewing old grout has always involved long hours of hacking away at old, worn grout with a tiny grout saw. Simplify the job by purchasing a grout removal kit that attaches to a Dremel tool. (See photo below). It has a high-speed carbide bit that effortlessly chews away old grout, and guides that keep you from chipping the tile edges.Attach the removal unit and set the bit depth to 1/4 in. Run the tool guides between the tiles and grind through the old grout. Use the grout saw to scrape out edges and corners and to clean out the joints.
Buy a Grout Removal Attachment
A grout removal kit contains the grinding guide and a grout saw for cleaning along edges where the grinder can’t reach. It’s designed to fit a Dremel tool.
Spread the grout
Vacuum up any dust or debris left after the grinding process. Take a chunk of your current grout to a home center or tile shop to find a match. Then, using a grout float, push the grout diagonally across and into the vacant joints.Also buy a latex additive to mix into the new grout to make it more durable. Mix the grout slightly thicker than peanut butter and then apply it.
Clean and polish the tile
Let the grout set up for approximately 20 minutes until a film develops over the tile, then clean the area. Wipe the excess grout and film off the face of the tile with a damp sponge, rinsing it often.
Buff with a cloth
When the film reappears, buff the entire area with a dry cloth. After the grout has dried for a week, protect it with a grout sealer.