The term hydrophobic coating is a bit of an unknown. Most homeowners are unfamiliar with this term, but considering the benefits such coatings provide, it’s well worth learning the science behind the theory, and how it helps your home.
In light of this fact, we’ve compiled the essential guide to hydrophobic coatings, and how they perform in practice. Here’s the lowdown…
What Is A Hydrophobic Coating?
Let’s start with the question what is a hydrophobic coating. The simple explanation lies in the word “hydrophobic”. The definition of the word is “tending to repel or fail to mix with water”. In other words, a coating that has hydrophobic properties will block water.
Advantages of hydrophobic coatings include: dirt retention, improved moisture resistance, improved corrosion resistance, self-cleanability, and extended life expectancy of the coating.
One of the reasons people are confused is because of the appearance of words like hydrophilic and super hydrophobic coatings. Let’s explore the differences between them in greater detail:
Difference Between Hydrophobic and Super hydrophobic
To start with, we have to define the relationship between the contact angle, and the character of the surface. This is the main difference between the coatings, and everything else is defined by that angle.
Hydrophobic coatings have a contact angle of ≥ 120°. Super hydrophobic surfaces have an angle of ≥ 150°. They are highly water-repellent, and, consequently, the best option for areas that experience high levels of moisture.
What are the factors that impact the angle of a water drop on the surface? The most important factors are the micro, macro, and nano-surface profile, as well as the surface tension of the coating.
Put simply, surface tension is the “elastic tendency of liquids that make them acquire the least surface area possible”. Water has a higher surface tension than common solvents.
As mentioned before, super hydrophobic is often thrown out there as a term, to the point where it became the “common nomenclature” for surfaces that repel liquids. And sometimes, it is used correctly.
However, don’t be fooled: Super hydrophobic coatings are not durable. We are not yet to the point where the technology is quite there yet.
A hydrophobic coating, on the other hand, is highly durable, and it is presently the best protection against liquids, moisture, and everything that comes with it.
Difference between hydrophobic and hydrophilic
Get your protractor at the ready: the difference is in the angle again. A hydrophilic coating is polarised, and has an angle of just 30 degrees. That makes the coating attracted to water.
A hydrophilic coating is polar, while a hydrophobic coating is non-polar. That is why the latter repels water and other liquids.
When water touches a hydrophobic surface, the droplets begin to accumulate, causing it to have a large contact angle.
On the other hand, with hydrophilic coatings, the surface attracts water and allows liquids to wet the surface. We all know that wet surfaces have lower insulation properties. But we will get to that later on in this article.