Different sealers are used for different grouts ceramic tiles. Make sure you have the correct sealer for the application. Add a second coat of grout sealer. Wait an hour and add a second coat of sealer using the same process to the cement tile. Test the second coat with a few drops of water – if they bead on the grout, then the grout has been sufficiently sealed. Depending on the grout sealer you use, it could take between 24-28 hours to dry completely.
Replace grout with caulk. If you are fixing the grout that has come loose bathroom tile next a toilet, sink, or tub, you might want to replace the grout with caulk instead of new grout. Silicone caulk is waterproof and can act as a better sealant in areas where there is a lot of water and can add some flexibility to the mosaic tile in areas where there is a lot of movement.
Check with an employee at the hardware store to make sure you are getting the right kind of caulk for the job. Clean out the seam so that no pieces of grout or other debris are present. Filling the wall tiles with a tube and caulking gun, gently fill the seam with a bead of caulk. For best results, keep moving as you apply the caulk.
Smooth the caulk. Use a wet fingertip or wet cloth to smooth the caulk. A small lip of caulk on the side of the tub will create a waterproof barrier between the tiles and the tub. A flexible buffer of caulk and less water seepage will lead to less wood tile problems later on.