Pitting corrosion and why your glass looks foggy after cleaning
Apr 07, 2026
You have seen it. A glass display that looks clean but has tiny white spots that will not wipe off. That is pitting corrosion. It is permanent.
What causes pitting
Cover glass is not chemically inert. The surface contains sodium ions. When exposed to acidic or alkaline solutions, those sodium ions leach out. The glass structure collapses locally. What is left is a microscopic crater - a pit.
Common culprits:
Hand sanitizer (ethanol plus glycerin)
Sunscreen (avobenzone and other organic compounds)
Salty sweat left to dry
Harsh glass cleaners with pH below 5 or above 9
Why it looks foggy
Pits scatter light. Each pit is a tiny lens. Light hits the pitted area and scatters in all directions instead of passing straight through. The result is a hazy, foggy appearance. Under magnification, it looks like a field of tiny craters.
Which glasses resist pitting best
Aluminosilicate glass (Gorilla Glass, Dragontrail) is more resistant than soda-lime. But not immune. Lithium-aluminosilicate (LAS) glass is even better. The smaller lithium ion does not leach out as easily as sodium.
Corning's Gorilla Glass Ceramic series uses lithium. So do some high-end LAS formulations from SCHOTT (Xensation) and AGC (Dragontrail STAR). These glasses are designed for chemical durability, not just mechanical strength.
Field data
A 2025 study from a Chinese smartphone brand tested 10,000 used phones. Pitting was found on 23% of devices after 18 months. Worse in humid coastal cities. Worse for users who work outdoors or exercise with their phones.
How to test for pitting resistance
ISO 10629 covers the surface durability test for glass. The glass is exposed to an acidic solution (pH 4) at 40°C for 24 hours. Then inspected under magnification for pits.
Ask your supplier for ISO 10629 results. If they do not have them, run the test yourself. It is cheap and takes one day.
Prevention is the only cure
Once pitting starts, it cannot be reversed. No coating or polish fills the craters. The only fix is replacing the glass. For buyers, this means specifying pitting-resistant glass for any product exposed to sweat, sunscreen, or harsh cleaners. Fitness trackers, automotive displays, marine electronics, and outdoor kiosks all qualify.
