Defining the quality of self cleaning glass

Does the contact angle define quality and durability of the coating for self cleaning glass?

This is probably the single most relevant question one can ask about any hydrophobic easy-to-clean coating and perhaps the MOST HIDDEN fact by most coating suppliers as it truly uncovers the truth behind the quality of the product. Yet, most coating suppliers will typically evade this critical issue with all sorts of misleading statements and false claims:

The unequivocal and irrefutable scientific FACT

The important fact to know is not necessarily the initial contact angle measurement after the glass surface is treated but rather how it will perform over time or, in other words, how will the contact angle behave with the normal tear and wear once the surface is exposed to the different environments.

Most hydrophobic easy-to-clean coatings have an initial contact angle anywhere from as low as 80 degrees to 120 degrees. The ones that are on the low end, especially under 95 degrees, are not interested, for obvious reasons, in disclosing any measurement thus they downplay or completely disregard any value to contact angle measurements, as they would not want to lose any “marketing edge” vs. any higher contact angle coating.

The contact angle measurement varies over time

You may hear a supplier calling this issue “the war of the bubbles” and the lack of relevancy they allocate since it really “doesn’t matter”, they claim. NOT quite so as it does matter and you should know why to therefore make a smart decision when choosing a coating for your own use, whether you are the owner of a building, business or simply for your own household or automotive use.

Specifically, the important aspect is to know how the contact angle measurement varies over time, thus if your coated surface still remains at a relatively high contact angle AFTER a significant period of time, let’s say after 1,2, 3 and more years to then be able to TRULY ASSESS the quality of the coating without the need to re-apply every few months, which is the case with MOST other coatings as they do not have a PERMANENT BOND.

Mediocre, good and excellent hydrophobic coatings

This is simply a matter of accuracy and disclosure of scientific facts that DO affect your every day life by having access to improved performance. The same way anyone likes having the best cleaner in the house, or perhaps the best paint for the living room walls, one should know the difference between mediocre, good and excellent hydrophobic coatings to enhance your glass surfaces and keep it cleaner for longer periods of time thus reducing the required maintenance.