Just the pHacts: pH and Stone Care
While reading information online, you will inevitably come across cleaning products that are referred to as
"pH neutral" or "low pH" cleaners. If you have ever wondered what those phrases have to do with maintaining
stone surfaces, keep reading. In this article, we will delve into the reasons why pH matters to stone
surfaces and how you cna benefit from knowing. So let's get into our exploration of the pHacts!
A Brief Explanation of pH
Before we get into the details of stone and pH levels, we need to establish exactly what the term means.
We hear the term used all the time in all sorts of contexts. As it relates to stone care though, you will
often hear pH mentioned in relation to a particular cleaning or maintenance product that is used on stone
surfaces. There is a good reason for this that we will get to further along in our discussion. For now
though, let's consider how to understand the term pH.
What Does pH Mean?
The term pH refers to a scale that is used to specifiy and communicate the acidity or alkalinity of a
substance. In fact,
Wikipedia.org says this about pH:
In chemistry, pH (/piːˈeɪtʃ/, denoting 'potential of hydrogen' or 'power of hydrogen') is a scale used to
specify the acidity or basicity of an aqueous solution. Acidic solutions (solutions with higher
concentrations of H+ ions) are measured to have lower pH values than basic or alkaline solutions.
But let's consider what pH is in simple terms. Liquids containing water all have a pH level that reveals how
acidic or basic the liquid is. The pH scale is a numeric range that goes from 0 to 14. Liquids that
register on the low end of the pH scale are considered acidic and liquids that register at the high end of
the scale are said to be basic (or alkaline). Thus, stone cleaners will fall somewhere in that scale. Below,
is a representation of the pH scale.
The pH Scale
As you can see from the scale, pH 7 is right in the middle of the scale. This value represents liquids that
are pH neutral. The scale continues to the right increasing in value moving into the basic (or alkaline)
range. Moving left, the pH value goes down into the acidic range. Knowing the pH value of a liquid tells you
whether the liquid is an acid, a base, or a neutral substance. But why would you want to know the pH of a
Why pH Matters
Why does it matter what the pH of a cleaner is? The short answer is, because some surface materials react
with acidic and/or basic solutions. Using the wrong solution on a stone surface can mar the appearance or
the finish of a stone. This is not something that comsumers want.
No matter what material your hard surface is made of, it will have at least some solutions that harm the
finish, the material itself, or both. Because of this, it is very important to know not only what material
you have, but also what it is composed of.
The cleaning and maintenance solutions that are used on a stone surface or other hard material can be the
difference between a long lasting, new looking surface and a challenging, worn looking one. Let's look at
some specific examples of how pH can affect hard surfaces.
Natural Calcareous Stone
Natural stone is composed of a variety of materials. Granite, quartzite, onyx, slate, limestone, marble,
soapstone, and travertine have different minerals in them. In fact, that is what makes a quartzite stone
different from a mable stone. Furthermore, even two stones of the same kind will have different mineral
content. However, there are certain things about mineral content that are closely related to what the stone
actually is. Let's consider an example.
There is a family of natural stone that contain calcite (also known as calcium carbonate). This group of
stone types includes the following:
All of those natural stones contain calcite. The stones are different from each other and are geologically
distinct from one another. But the differences stem from how they are formed; they all have calcite as their
main mineral. These are known as "calcareous" stones; that is, they contain calcium carbonate. Going back to
the example we mentioned a moment ago, marble is a calcareous stone but quartzite is not. Quartzite contains
absolutely no calcite, but it can look very much like marble. If you are wondering what this has to do with
pH, we have arrived at the point.
Calcareous Stone Etches
The pH of cleaners and surface treatments
will damage calcareous materials if the pH is
. Acidic liquids dissolve (or eat away) the calcite that is in calcareous stone. And it
does not have to be extremely acidic either. Coffee's pH can range from a 4.5 - 6.0, but it reacts with the
calcite. The result? The stone becomes dull looking or perhaps is darkened; depending on the finish and the
kind of stone it is.
So in the case of calcareous natural stone, using the wrong cleaner can literally make your surface
disappear a little bit at a time. This issue is able to be repaired using an
etch remover for calcareous stone. However, with a
bit of diligence and information, prevention can be a better solution. But Calcareous stone is not the only
material that requires specific types of cleaners.
Just like natural stone has a specific composition, engineered stone also is composed of very specific
materials. In the case of quartz countertops and other surfaces, the composition is the following:
- Quartz, the natural mineral.
- A binding material (usually a polymeric resin).
- Coloring pigments to control the appearance.
This results in a durable, non-porous surface that is easily cared for and maintained... ...provided that
you care for it according to manufacturer's insrtuctions. Unlike the example mentioned previously, quartz is
not highly reactive to all acids. Some acidic cleaners are just fine as long as they are used properly and
the instructions are followed carefully. That is not to say that all acids are acceptable. The proper
cleaners have to be used on quartz just like the right ones have to be used on stone containing calcite, but
the reasons are different.
Quartz and pH Levels
The directions for cleaning quartz and what cleaners are acceptable vary from one manufacturer to the next,
but the common thing they all mention is not to go too far away from the middle of the scale. The tendency
of instructions is to recommend a slightly acidic solution but you should
always follow the
isntructions given to you by the manufacturer of your material
. However, let's look at one reason
slightly acidic cleaners are effective for quartz.
Since quartz is non-porous and does not absorb liquid, anything that sits on the surface and dries will
leave residue on the surface. This residue can be tough to remove. For example, regular tap water that is
left to dry on the surface of quartz, can evaporate and leave mineral deposits behind that are stuck to the
stone. One of the predominant minerals that is found in some water supplies is lime. What is lime made up
of? Calcium carbonate. Does that sound familar? We have already discussed what dissolves calcium
carbonate effectively; acid! So using an acidic
cleaner for quartz
breaks down mineral deposits (also known as lime scale) from quartz surfaces. Removing all
of the cleaner from he quartz is very important and you will need to dry the surface thoroughly after
Even if you are not trying to remove lime scale, using the appropriate
daily quartz cleaner can help you get
the most mileage out of your quartz surfaces. But what about alkaline (or basic) cleaners, do these have
The pH Spectrum and Sintered Stone
Another material that weighs in when it comes to examining the pH of surface treatments is sintered stone. Sintered stone surfaces are like quartz in that they are non-porous and they are like natural stone in that they are made up of natural minerals without resins. This means that they are in a class by themselves. Sintered materials vary and sintered stone in particular is a material that is described using various labels. Some of the manufacturers of this material include:
The material is produced through a sintering process that subjects the raw material to intense heat and pressure, the material is then transformed into a solid mass of material that is very hard. So, how does pH come into play when it comes to sintered stone? Sintered stone can be cleaned using a wide range of cleaners and care products. So, to find the
best cleaner for sintered stone will depend on what you are trying to clean off it.
Let's look at an example. DEKTON® is a sintered stone that can be cleaned using many different cleaners. The list of cleaning products recommended by Cosentino includes acids, oxidants, solvents, and alkaline products. So how do you know what to use? The manufacturers provides a table of stain-causing substances and which of those cleaners will work on the given type of stain. There are also specific cleaners that are listed as not being approved. The idea here is that sintered stone is tolerant of a wider range of pH liquids. And, like all the other materials we have mentioned, you have to know a bit about what works on each type of material you have and follow the instructions.
In conclusion, natural stone, engineered stone, and sintered stone all respond differently to liquids with various pH levels. However, knowing a bit about what pH is and how it interacts with a surface you are trying to care for can yield benefits. Namely, longer life, better looking surfaces, and perhaps even an easier time cleaning the surface.