Glass coatings have been around for years. You might see manufacturers use terms such as “self-cleaning glass” or “glass conditioners.” Don’t let their marketing lingo trip you up.
There are basically two types: hydrophobic, meaning they repel water, or hydrophilic, meaning they attract water.
Glass being a very porous and microscopically rough surface is a magnet to dirt, contamination, bacteria and various other deposits. This, over time, deteriorates the surface, brilliance and clarity of the glass. This is why you will find shower doors which cannot be cleaned, no matter what cleaning material is used.
Both types of coatings fill in the microscopic peaks and valleys present in virtually every glass surface, resulting in a smoother surface. That is where the similarity ends.
Hydrophobic coatings create a surface that repels water. Supporters claim that by repelling water and the minerals it carries, fewer drops can stick to and dry on the glass, resulting in fewer spots. When it comes time to clean the glass, those spots can’t stick as easily to the smooth surface and are easier to remove.
Hydrophilic coatings create a surface that attracts water. Supporters claim that by attracting water, it sheets off and carries away any loose materials. The remaining water that sticks to the glass is spread out, so it deposits the mineral content broadly, and staining isn’t immediately noticeable.
Essentially you have two contrasting approaches, but the same result: a surface that exploits the dynamics of drop formation and wetting to maximize dirt removal when doused with water.
Many hydrophobic products claim to make your surfaces more scratch-resistant. Some require professional application and a longer curing time.
Surfaces coated with a hydrophilic substance will naturally dry out quickly. This could prevent windows, mirrors or shower enclosures from fogging up when in contact with steam or condensation.
If you are going to use one product, the shower door industry seems to prefer hydrophobic coatings for reducing the amount of water and minerals that can stick to the glass causing hard water stains.
From my general research, it seems for the best results, many manufacturers are recommending using a hydrophobic coating as a base coat for a hydrophilic glass coating with reapplication every 6 months.