Porosity: A pithy primer
Porosity: If you're a regular reader of Surfacepedia, you're probably familiar with the term. And if you're a homeowner who happens to have a prominent feature made from natural stone – such as a granite countertop or travertine tiles in your bathroom – then you're intimately acquainted with the perils of porosity.
But what is porosity, really? And what determines it? Have you ever asked yourself these questions? Perhaps next time you're using Dry-Treat's HANAFINN Rejuvenata ACTIVE™ to carry out some heavy duty stain removal on a stubborn mark, some of the following information will flash through your mind.
What is porosity?
Porosity is related to the ability of a substance to pass through the surface of a material, becoming absorbed in it. But you might be surprised to learn that this is not actually what it means.
When you talk about the extent to which water, for example, can flow easily through a stone, you're actually talking about that stone's permeability. Porosity, by contrast, refers to the amount of open space inside a stone. Of course, these two concepts are interconnected – a greater degree of porosity means a greater degree of permeability.
What determines porosity?
All matter is essentially made more of nothing than something. Not only are the tiny atoms that form every physical thing in existence made from even tinier particles huge distances apart, but all atoms have tiny spaces between them.
But those aren't the gaps that matter to us, as natural stone enthusiasts. These atoms make up the microscopic rock grains of which stones are made of, all of whom also have tiny spaces between them, invisible to the naked eye. It's these gaps which create porosity, serving as vacuums which water, gas, oil and other substances can fill.
So next time you wonder why granite is less porous than limestone, or slate, you need scratch your head no longer. Think about these tiny 'micro-voids' as they're known, invisible to you but very real – and potentially very threatening to your stone.