Concrete is frequently used in construction because of its strength and durability. You probably have it under your carpeting, unless you have wood floors, and it is also frequently used in the garage and basement. While concrete is a useful building substance, it is not necessarily aesthetically pleasing. Many home and business owners cover it with carpeting or tile. Concrete sometimes needs to be sealed before it can be tiled. Fortunately, sealing a concrete floor for tiling is not difficult.
Wash the floor with warm water, a mild detergent and a mop to remove any dirt or debris from the concrete. If stains remain after the floor dries, scrub them out with a scrub brush and a floor cleaner. A degreaser will be effective for oil stains, while oxalic acid works well against rust stains. Follow all instructions on the back of the cleaner containers, and allow the floor to dry.
Apply a concrete sealer to the floor with a bucket and mop, a roller or a sprayer. Start at the end of the room farthest away from the door and work backward toward the exit so you don't have to track back over wet sealer to exit the room. Allow the sealer to dry over the next several hours.
Apply a second coat of sealer once the first coat is dry.
Your concrete floor should be level if you plan on installing tile. If there is any unevenness, it is likely to cause cracks in the tile down the road and you'll want to use a leveller on the concrete before sealing it. Applying fans to the area can speed the drying process, but the fans must not be sitting on the wet sealer themselves and they must not be on too high. Overpowered fans will push the sealer across the floor and cause it to dry unevenly.
Ceramic tile may have trouble bonding to concrete sealer and unsealed concrete is best for the ceramic tiling process.