How hydrophobic glass coatings exhibit the ‘lotus effect’.
Water Repelling Glass
When glass is left exposed to the elements for a long time, it often accumulates heavy deposits of such materials, which won’t come off from simple cleaning. Being a porous and microscopically rough surface, glass also attracts dirt, bacteria and other deposits. A lot of the dirt and grime goes deep in and settles there, which is why surface treatments cannot dislodge them.
There are many areas, where it is imperative to keep glass surfaces clear of water and dirt. Based on water repellency, glass coatings are of two types: hydrophilic and hydrophobic. It is important to make the surface react to the water in such a way, that the clarity of the glass is not lost. For this reason, it is common for glass in certain industrial applications to carry a preventive coating, of either the hydrophilic or the hydrophobic type.
Hydrophobic glass coatings cause the glass to exhibit the ‘lotus effect’, which is the method of water repellency employed by the flower of the same name. The coating works in effect as a shield much the same way as Teflon coating does on a frying pan. It acts as a non-stick buffer, which the water runs off, without leaving behind any streaks. To the observer, there are no beads formed on hydrophobic glass either, which is because the surface does not allow any to form.
Hydrophobic Glass Coating
Coatings of this type are generally silica based and create a remarkably thing film – with a thickness measurable on the Nano scale – which covers dents or depressions on the original surface. No dirt or grime is afforded a hold on what is a totally smooth surface. The major benefit of this type of glass is that it is self-cleaning, which works to repel dirt or organic as well as inorganic origin. Graffiti and paint don’t affect hydrophobic glass, and these coating can be reapplied on-site. You could even have it on both sides of the glass.
Another plus point of hydrophobic glass coatings is that they cost less than hydrophilic type glasses, almost half of what the latter would require spending. And being based on a basic principle that repels water molecules instead of attracting them, it is also much more widely preferred in many industrial applications. At any rate, hydrophobic coatings are usually better than having none.