Unlike carpet cleaning, where heat plays an important role in cleaning efficiency and quality, hard-surface cleaning requires the use of high water pressure to achieve above-average results.

However, hard-surface cleaning does require you to limit your pressure to within a safe operating range, depending on the type of surface you are cleaning. (Click here for "Pressure range")

Typically, the harder the tile is, the higher the pressure you can use to clean it.

The Mohs scale, devised in the early 1800s by German mineralogist Friedrich Mohs, is an easy way by which hardness of substances can be measured in relation to one another. (Click here to see "Mohs Scale of Hardness")

Let’s look at some hard surfaces and the types of pressures at which they can safely — and effectively — be cleaned.

Man made and fire-hardened

Ceramic, porcelain and quarry tiles are man made and fire-hardened. These usually don’t pose problems as they are often the hardest and can be cleaned at pressures up to 1,450 psi.

You can clean these at higher pressures, but you risk the possibility of damaging the grout. Also, the increase in pressure after 1,450 psi does not dramatically improve your cleaning results.

Natural stones and man-made clay stones are a different story.

They can be of varying hardness, and thus require proper identification for best cleaning efficiency and quality.

Granite

Granite is the hardest of the natural stones. It is an igneous stone that comes from volcanic material, such as magma.

Liquid magma cools and solidifies underneath the Earth’s surface, and then mineral gases and liquids penetrate the stone and create new crystalline formations and various colors.

This means that granite is much like the man made ceramic and porcelain tiles that are fire-hardened.

Therefore, the cleaning pressure can be up to 1,450 psi.

Marble

Marble is the most common of all natural stones.

It is a metamorphic stone that comes from natural change — one type of stone to another — through the mixture of heat, pressure and minerals.

The change can be a development of crystalline formation, a texture change or even a color change.

It is a much softer stone and should be cleaned at lower water pressure, around 800 psi.

Slate

Slate is also a metamorphic stone. It is formed from clay-rich mud through tectonic stress and is believed to have started forming 570 million years ago.

It was created when sediments of organisms on the seabed formed mud deposits. Pressure and temperature in the Earth’s crust squeezed the mud into layers of shale that eventually caused it to move upward.

It is these natural layers that pose a challenge in cleaning slate.

Pressure greater than 800 psi can break off a piece of the layer and permanently change the appearance.

Sedimentary stones

Limestone, sandstone and travertine are all sedimentary stones that come from such organic elements as glaciers, rivers, wind, oceans and plants.

Tiny sedimentary pieces break off from these elements and accumulate to form rock beds.

They are bonded through millions of years of heat and pressure.

Travertine is the softest in this group and it also has holes that have been filled with epoxy to give it a smooth surface.

When cleaning travertine, keep your pressure around 800 psi. There is more leeway with sandstone and limestone.

Man made tiles

Saltillo and terracotta are two common man made tiles.

They are made from clay and then mostly sun-dried. In the case of terracotta, it is somewhat fire-hardened, which makes it a little harder than saltillo.

Saltillo is very common in the United States because it is made in Mexico and the short transportation across the border keeps the price low.

When dealing with saltillo, keep your pressure around 800 psi.

With terracotta, there is more leeway.

Chemicals and cleaning

Just like carpet cleaning, where the temperature of the water plays an important role, the chemicals used are also extremely important for efficiency and quality.

The softer the stone, the more porous it tends to be.

If you have spills that may have penetrated the surface of the tile, then you will need to give your prespray time to absorb into the tile to help remove stains.

Products that contain oxygen work great in these situations.

The oxygen gets absorbed into the tile, producing a safe bleaching action to help remove organic stains.

Taf Baig, an Institute of Inspection, Cleaning and Restoration Certification (IICRC)-certified Master Textile Cleaner, started a successful carpet cleaning company in 1991 and sold it in 2003. He is president of The Magic Wand Company, a manufacturer and distributor of all types of cleaning products. Taf’s marketing seminar information is available online at www.magicwandco.com, or call (877)926-3748.