Tile Identification
Before cleaning, it is important to identify the type of tile. Some soft stones should be cleaned with low pressure. Also, the use of chemicals is needed, even with a high-pressure cleaning system. Using the wrong chemical can damage certain natural stone tiles.
Natural stones, such as marble, granite and limestone, should not come in contact with acid cleaners. The acid will etch, or corrode, the surface of the stone.
Grout and Tile Cleaning Chemicals
Manufacturers offer a plethora of grout and tile cleaning chemicals to be used as a pre-treatment before pressure washing the grout. For most applications, an alkaline solution will loosen the dirt and is safe for most tile types. Consult the manufacturer's instructions for specific uses and limitations, however.
For grout that has stubborn stains or will simply not come clean, an acid cleaner may do a better job. Acid cleaners, however, cannot be used on marble, limestone and other natural stones.
Pressure Washing
Several kinds of pressure washing wands for use on floors and hand tools for use on walls are available at janitorial and carpet cleaning supply houses. These tools require either a truck mount cleaning system or a portable machine outfitted with a high-pressure (1,200 psi) pump and strong vacuums.
Units such as the Hydro-Force SX-12 for floors and the Hydro-Force SX-7 hand tool for walls use a spinning head inside of a round shield. The spinning head is outfitted with two spray nozzles that blast dirt and grime away from the floor or wall before it is immediately vacuumed away. The technician can glide the unit over the surface in any direction he pleases. For best results, an overlapping pattern of either up and down or left and right should be used.
Other units look similar to a standard vacuum drag wand or upholstery tool. Inside the wand are spray jets that blast the dirt away as the vacuum removes dirt and water. These wands must be used in an up and down fashion.