Natural Limestone Surfaces
You may not readily think of this material when someone begins talking about natural stone surfaces. However, Limestone is a material that has many applications in the world of natural stone architecture. In this article, we will ponder some of the details regarding natural limestone surfaces. We will talk a bit about what the material is, some of its properties, and how it is used. Then we will briefly consider what to keep in mind when working with limestone. Finally, we will conclude with some things to keep in mind regarding the care and maintenance of natural limestone surfaces.
What is Limestone?
Natural limestone surfaces are composed of the natural material limestone. But what is limestone? Well, a generic answer could be simply stated this way: “limestone is a sedimentary rock that is found in aquatic environments.” But if you are interested in a more detailed explanation of what limestone is, there are many resources available online. Those resources have more in-depth definitions of what limestone is. For example, note how it is defined on Wikipedia.org.
Limestone is a common type of carbonate sedimentary rock. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes have likely been more important for the last 540 million years.
Why Does Composition Matter?
What a natural stone is composed of affects many facets of the stone’s uses, appearance, and even the care and maintenance required. Additionally, how the material must be worked is affected by the material of which it is composed. As a result, materials that are made up of the same minerals, will have similar traits and are said to be related.
How is Limestone Used?
If we were to list every single use for limestone in its various forms, the list would be much longer than you probably have time for so we won’t even try to publish an exhaustive list. What we will do however, is give you a representation that gets the idea across. Limestone powder, dimension stone, slabs, and tiles are used in a number of ways for all sorts of practical products including:
- Flux Stone
- Wall Panels
- Floor Tiles
- Dimension Stone
- Soil Conditioner
- Roofing Granules
- Mine Safety Dust
- Building Facades
- Animal Feed Filler
- Sculpture Material
From the above list it is easy to see that limestone is a diverse material that has many uses and takes on many forms. Its usefulness is a product of the mineral of which it is primarily composed. For the rest of the article we will talk about limestone in the contet of it being used as a surface material. But we wanted to show just how useful the material is and how it permeates multiple environemnts in various forms.
Properties of Natural Limestone
As a surface material, natural limestone is usally a light color. Often landing in one of the following hues:
Again, this is due to that fact that it is made up mostly of calcium carbonate (also known as calcite). Natural stone composed largely of calcium carbonate is referred to as a calcareous stone.
Calcareous stone is relatively soft compared with other natural stone materials. Because of this, limestone comes in at a 4 or 5 on the Mohs scale of mineral hardness.
Like all natural stone, limestone is porous. However, the porosity of each slab of limestone or limestone tile will vary from one to the next. The porosity of a particular stone can be tested by performing a water test on the stone of interest. The faster the tile or slab absorbs the water, the more porous the stone.
Working With Natural Limestone Surfaces
When it comes to working with limestone, there are a number of common tasks. One such task is cutting. Artisans cut limestone tiles, panels or slabs just as they cut other natural stone. However, professionals use specific blades for cutting natural limestone. Manufacturers design these blades to cut softer stone. Hard materials like porcelain require a diamond blade for cutting ceramic surfaces. Likewise, softer stone is best cut using a diamond blade made for the material.
Other tools exist for working with natural limestone surfaces. Core bits, cupwheels, and edge profiles are all examples of diamond tooling made for use on stone materials like natural limestone.
Caring for Limestone
Caring for limestone involves many of the same practices that go into maintaining and caring for other natural stone such as granite, marble and quartzite. Of those three, limestone is most like marble. In fact, limestone and marble are so closely related, it is not uncommon to see stone referred to as “limestone marble”. we won’t get into the weeds expalining why this happens or what the technical differences are, but the point is that marble and limestone are very similar.
Natural stone materials require sealing to keep stain causing water-based and oil-based liquids from penetrating the pores and discoloring the stone. Impregnating stone sealer slows the absorption rate of limestone surfaces. Hence, owners benefit from having more time for spills to be cleaned up. As a result, sealed natural limestone surfaces resist staining. How often limestone requires sealer to be applied will depend on a number of things.
The first key factor contributing to the frequency of applying sealer to natural limestone is the porosity of the stone. Each stone has its own porosity. Another factor is the amount of time since the last sealer application. Finally, the type of daily cleaner that is used to clean the surface. How can you tell if a limestone surface is ready for a sealer application? By performing a simple water test on the stone, you can determine if it is time for another application of stone sealer.
Natural limestone requires periodic sealing. Some cleaners destroy stone sealers. Therefore, daily care of limestone involves specific cleaner. Thus, many recommendations exist online for cleaners formulated as natural stone cleaners. The key thing to keep in mind is some cleaners breakdown stone sealers. So make sure the cleaner you select is the proper formulation.
Limestone still stains even if it is regularly sealed and is cleaned with the proper cleaner. Some stains occur from oil or water based liquids. However, there are other kinds of stains too. Rust stains limestone in certain situations. Wet metal left on a limestone surface for a period of time eventually rusts and discolors the stone. Removing rust from a limestone surface is achieved by using a rust remover on the stone.
Etches on limestone surfaces are often called stains even though they technically are not stains.. Calcareous stone etches when a reaction occurs in it. Acidic liquids dissolve the calcite in calcareous stone. Etching appears as a dull spot if the stone has a polished finish. And on honed finished stone they appear as a dark spot. When limestone gets an etched, consumers use etch remover to restore the appearance.
The last form of maintenance we will mention here is refinishing. Consumers usually don’t need to this done. However, professionals use this technique to restore limestone surfaces. Refinishing natural stone involves using diamond polishing pads. Professionals use polishing pads on limestone to achieve the initial finish. Restoration professionals also use this technique if the surface requires it.
As we have seen in this article, natural limestone is a versatile and useful natural stone material. Artisans use specific tooling while working it. And consumers and professionals alike use particular surface treatment products to maintain it. Knowing about these product and techniques gives stone workers and owners the opportunity to overcome a number of potential challenges that come with natural limestone.