The finishing step to installing tile on the floor, along the walls or in the shower is grout. Grout is a mortar-like substance that is used to fill in the areas between the tiles, secure the tiles in place and give the area a finished look. The problem is that grout is not very waterproof. There is a strategy required for properly sealing grout to prevent future problems.
Things to Remember
Grout needs to remain slightly moist while it cures to prevent the creation of dark patches. You will need to monitor your grout to ensure it cures properly and cures all in one colour. If the sun comes through a window and shines on a particular part of your grout for hours every day, you should block the window with a thick curtain. Grout near a heater or furnace vent will dry too quickly, so make sure you spray it with a little water each day to keep it drying at the same pace as the rest of the grout. Don't worry, the grout will still cure properly even if you are keeping it a little damp.
How Long to Wait
Allow the grout to sit for at least a week before you consider sealing it. If you have tiled a shower, put a plastic protective sheet over the grout to allow it to cure properly. After a week, check the grout to see if it is the colour you want it to be and that it has cured to a single colour. Grout can be beige, grey or a variety of other colours. You will know it is dry when it has reached the colour on the container. If it is not dry after a week, give it one more week. Two weeks is the maximum you should wait to seal your grout.
Why You Should Wait
If you seal grout too soon, you run the risk of having a few things go wrong. You are trapping moisture in the grout, which means it could take a very long time for sections of the grout to cure, and when it finally does cure it will cure in a variety of colours. Moisture trapped in grout also means the grout is not as strong as it could be and may start to fall out. You may also start to see mould forming around your tile if moisture is trapped in the grout. This is why patience is needed when waiting for grout to cure.