How to Remove Mortar Before Grouting

Use a grout saw to make a cut in the center of the grout joint down to the subfloor. If the joint is less than 1/4-inch wide, use a utility knife to cut the grout joint.

Use the utility knife to pry the grout from the edges of the tile. Then use the knife to slice toward the center cut previously made with the grout saw. The grout should then break away from the joint.

Connect a hose attachment to a shop vac and switch on the vac. Run the hose over the joint to vacuum up the grout and any other debris.

Open a container of vinegar and pour the vinegar directly onto any tiles surrounding the grout joint. The vinegar will remove any grout haze on the tile. Allow the vinegar to soak in for 5 minutes.

Use a nylon brush to scrub the surface of the tiles or other material. Apply the brush to the entire surface to clean any residual debris left from the grout removal.

Move a cleaning sponge slowly across the surface to soak up the vinegar. Run clean water over the sponge and then wipe the tiles with the sponge. If the sponge moves smoothly across the tiles or other surface and then slows down over a specific area, that area still has residual grout debris. Scrub the area a second time with your nylon brush and then wipe it over with a clean, wet sponge to clean it. Allow the tiles or surface to dry fully.