The old grout might be moldy and beyond cleanable.
How to remove tile grout off walls.
Use a ball peen or masonry hammer and cold chisel to tap the pieces free.
In some cases the only way to tear out the ceramic tile is with heavy equipment such as a jackhammer or air chisel.
Fit your utility knife in a sturdy holder if you have one and run it carefully and repeatedly around the tile or tiles you plan to remove.
There are a few good reasons why you might want or need to remove old tile grout.
This method takes a while but comes with a low risk of damaging the surrounding tiles.
Fortunately there are a few methods that can help to remove even the most stubborn dried on grout from tiles without damaging the finish of the tile.
Grout is made from water cement and sand which hardens over time to form a rock like material.
Begin by giving the tile a good cleaning with a sponge and soapy citric acid water as adescaling solution and use a toothbrush to deep clean grout to remove deposits and stains that may make removal more challenging.
Scrape the grout away with a utility knife.
Wipe the tile dry with a clean towel to make sure all grout is removed.
Use the scraper to clean off large debris and then clean off any soapy residue with a damp cloth.
Wet grout is easy to wipe away with a damp sponge but because it is comprised mainly of cement it can be very difficult to fully remove dried grout from porcelain tile.
How to remove grout.
How to easily remove old tile adhesive and grout from walls using a heavy duty scraper uploaded by upload to youtube for windows phone.
If some grout remains repeat scrubbing it with the sugar water.
Rinse the tile with clean water to remove the sugar solution.
Always wear safety glasses when removing ceramic tile.
If you are grouting ceramic or porcelain wall or floor tiles it can be easy to leave small lumps of grout on the tiles surface and around the joints.
Armed with this handy tool you can remove 15 square feet of grout on 4 by 4 inch tile in about one hour.