A power grout saw is an ideal way to remove grout that has been damaged by time and exposure to moisture in your kitchen or bathroom. A power grout saw can be used in a similar way to a hand ground saw.
Step 1 - Removing the Grout
Plug the power grout saw into an electrical receptacle and then use it to remove the grout from the tiles. Start by positioning it in between the tiles and pressing the trigger. This should churn up the grout and get rid of as much as possible. Go slowly so that you don't risk causing damage to the tiles.
Step 2 - Removing Leftover Grout
If any grout was not removed by the power grout saw then this should be manually removed by using a craft knife. This will be able to get rid of all of the grout in between the tiles.
Step 3 - Vacuuming
Wipe the surface of the tiles down by using a soft damp cloth to get rid of any grout left on the tiles. Then you can vacuum up the dust created when you removed the grout from the wall.
Step 4 - Re-Grouting
Once the grout has been removed you can then re-grout the tiles as you would normally.