When you set out learning how to grout tile, it may be due to crumbling or disintegrating grout in your tiles that were laid by someone else. This happens if too much water is added to the grout mixture when it is initially made. Nearly all tile floors have grout made with Portland cement. Some brands of grout might have added ingredients like acrylic modifiers or powdered latex, to help them bond better. Liquid acrylics can also be mixed into your grout, which will make it more durable.
Portland cement is not stable. It only becomes stable when it’s mixed with water. It can pull water from humidity in the air, or from water you will mix it with. Grout should be of a consistency that sticks easily to your putty knife, but it should not fall off your knife. If it does, it’s too runny. When you begin to mix the dry portion of grout with water, it should originally look like a powder. There shouldn’t be any clumps or lumps. If you have clumps in your dry powder, it has already started mixing with a source of water vapor in the air. The grout should look like a bag of flour, before you mix it.
When you mix water and grout, don’t just add random amounts of the ingredients. It’s just like making pancake or cake batter. Don’t add too much water, or you’ll be trying to determine how to grout tile with a mixture that is too runny.
Your grout mix of Portland cement and water should be the consistency of thick cake batter. Once you mix grout, if it appears too runny, add more of your powdered grout and blend it until it thickens. This is why it’s a good idea to mix only part of your grout bag at the start. This will leave you with extra powder, in case you mistakenly add a too-large amount of water when you mix it. You will also only want to mix as much as you’re going to be able to apply within a half hour.
Grout can also be ruined by an installer even if the mixture is exactly right. If the bottom of the bucket was getting dry, he may have added water, and this breaks down the bonds that hold grout together. Your grout will not be a plastic compound any more, it will be like rock.
Grout cures the best in an area that doesn’t have a lot of humidity. But if your humidity is too low, the water in your grout mixture may evaporate too fast. If this occurs, your grout may lose strength. You can cure grout in an area with low humidity by covering your tiles that have just been grouted with damp white-colored paper towels. They will stick to the tile and give it a “drink”. Then you will need to mist the paper towels each hour so that you’ll have learned how to grout tile with the fewest problems.