Stone Floor Maintenance: Travertine
May 7, 2008
I recently received a call from a perplexed technician regarding a stone floor on which he was working. He indicated he had polished the floor with diamond abrasives, and that overall the floor had excellent gloss but, try as he might, he could not polish out the traffic lane in the entrance.
When I asked him to identify the floor, he said it looked like sandstone, but thought that it might be marble. At this point I was the one who was perplexed, so I agreed to meet him at the building and have a look at this challenging floor.
After entering the building and looking back across the lobby, it was evident there was a traffic pattern at the entrance. True, the floor was highly polished, but there were two subtle yet distinct paths that forked to each of the elevator banks. The traffic lanes did not appear eroded like normal traffic patterns; they just looked a little soiled. It didn’t take long to identify the cause for the problem, and it began with identification of the flooring material. The natural stone flooring in question was travertine.
The calcium carbonate classifications of natural stone flooring consist of limestone, marble and travertine. Limestone is a sedimentary rock comprised predominately of calcite in the form of the shells and secretions of marine organisms deposited on the ocean floors, subjected to extreme pressures. Over time the deposits solidify and slowly become limestone. Marble is often metamorphic limestone; limestone that has been exposed to extreme heat and pressure, such as that caused by continental plate tectonics, that re-crystallizes the stone into marble. Both of these stones polish up quite nicely because they are, for the most part, solid through and through.
That is not the case with travertine. Although sometimes referred to as travertine limestone or travertine marble, it is technically neither. The formation of travertine is what makes it different than the other calcium carbonates and, by extension, why it can cause maintenance challenges.
Travertine is a sedimentary rock that is formed by precipitation near pools of mineral rich water usually associated with hot-, warm- or cold-water springs. The calcium carbonate in the water deposits along the perimeter of the mineral springs and, over time, collects into dams. These dams continue to grow until the water finds a different path or the source is discontinued. The water withdraws and the dams, which ultimately become travertine, remain. During this re-crystallization process the calcium carbonate will cover whatever is on its surface, such as debris, plants, and tiny creatures, and encrust it in the mineral. The organic material decomposes and, as a result, the body of the travertine is usually very porous, with lots of pores, pits and cavities throughout.
Travertine comes in many colors and may appear layered when cut against the bedding plane, or globular when cut along the bedding plane. When travertine is used for flooring material, the voids are usually filled with cementitious or synthetic fillers such as epoxy and polyester, and can be polished smooth to a honed or high-polished gloss. The fillers eliminate the voids, making maintenance much easier; this type of travertine is referred to as filled travertine. Some installations utilize tumbled, brushed or unfilled travertine to enhance the natural beauty of the stone and expose the pores; these are considered unfilled travertine, which can become soil collectors and a maintenance challenge.
The initial maintenance for travertine may include filling of the pores with cementitious or synthetic fillers and polishing them to the desired gloss level using diamond abrasives and sealing them with a penetrating sealant or impregnator. These floors will also respond to powder polishes in the same manner as limestone and marble due to the calcite in the stone. It is also not uncommon to see water-based floor seals and/or finishes applied in the same manner as maintaining resilient flooring.
Daily/routine maintenance for travertine floors is relatively simple: sweeping, dust mopping or vacuuming on a regular basis followed by wet mopping with neutral or all-purpose cleaner, the latter being predicated by the type and amount of soil being removed. When the travertine is high polished it is better to just use neutral cleaner when mopping, as it will help to prolong the gloss; alkaline products may dull the gloss if overused or used in excess. As with all calcium-based stone floors, do not use acid-based cleaning products on them because acid has a tendency to dissolve them, which will etch the surface.
Periodic maintenance may include the use of powder polishes, diamond abrasives or, in the case of water-based acrylic products, machine scrubbing followed by applications of more finish. Periodic conditioning/restoring followed by high-speed or ultra high-speed buffing or burnishing may also be used to restore high levels of gloss when polishes are applied.
Travertine (filled or unfilled) with or without polishes will ultimately succumb to the damaging effects of erosion, and traffic patterns will appear that do not respond to daily/routine or periodic maintenance. In the case of unfilled travertine, the pores will be filled with soil and regular or periodic cleaning will not dislodge it. As it is very difficult to get the soil out of the pores, it may be necessary to abrade the surface below the contaminated area and polish it again.
In the case of travertine with an acrylic polish applied, it will be time to strip and refinish the floor. The objective of stripping and refinishing is to remove all pre-existing floor seals and/or finishes, and re-apply the polish. The polish may be a no-buff, high-speed or ultra-high-speed chemical system that will be maintained in accordance with the manufacturer’s recommended maintenance methods.
Filled travertine, such as is the case with my perplexed technician, is different. The traffic lanes that were visible were not the result of tiny scratches in the surface; he had effectively polished those out with the diamond abrasives. The subtle traffic lanes he was experiencing were the result of the synthetic filler popping out in the surface, creating micro-pores. Additionally, the more he polished, the more of these micro-pores he exposed, giving the illusion of a traffic lane when in reality it was just thousands of these tiny micro-pores not reflecting light. The solution to this problem was to fill in the micro-pores with filler before using the diamond abrasives. Once the pores are filled and the stone polished, maintenance can resume using powder polish or crystallization.
Floor maintenance begins with identification of the flooring material. By understanding how travertine is naturally formed, the technician has a better comprehension of the material and the properties and characteristics it possesses as well as the problems associated with it. This information helps to explain why travertine reacts the way it does when exposed to traffic conditions. The technician can then proceed to get additional training and education to address the issues and concerns of the customer, and provide them with the end result they are looking for.