Understanding glass staining (glass corrosion)
What Is Glass Staining? What Is Glass Corrosion?
There are many expressions in use to describe this type of damage.
Hard water stains
“Acid rain” damage
From a scientific point of view, however, they are all the same thing, namely glass CORROSION. Yes, you have read correctly, glass does corrode (!), the appearance of it may vary under different circumstances, but in essence, it is always due to the same process. It is not something that deposits on the glass, but something that “eats” into the glass. We do recommend to mechanically polish stained (corroded glass) rather than just treat it with an acidic product (There are many on the market, but quite often they only provide a temporary solution and may make the problem worse in the long run).
What causes staining on glass?
1) prolonged exposure to water, especially hot water. You can probably think of a few examples for that:
Exposure to sprinkler systems
2) An alkaline (not acidic) environment. Examples of these are:
Exposure to mortar, lime or concrete
Soapy environments such as shower enclosures
Glass corrosion starts very slowly when glass is exposed to water for extended periods of time, but it is a self-perpetuating and even self-accelerating process as any water on the surface turns more and more alkaline. Sodium compounds get leached out of the mix of minerals in the glass which in turn makes the surface porous and allows more and more corrosive substances to settle in the microscopic cavities. The result is milky, frosty looking glass.
If you are interested in the technical details, here are links to a couple of excellent articles on the subjects
This article is advertising a nano-coating for glass, but the technical explanation is quite good. It also says that nothing can remove glass staining. We would like to politely disagree with that. Just check our projects page
Max Richens is an authority on glass corrosion and he wrote an easy to understand article, which you can find here. Take note of the use of vinegar or lemon juice to remove staining, which is promoted by so many blogs and forums!!!
For more information on preventing and removing staining check this link to specific pages on this site