Does sweat corrode glass touchscreens on phones, or other glass surfaces, over time?
What about plastic?
Sweat is a pretty dilute solution of some fairly harmless chemicals, so I think we can fairly say that it is not going to have any significant corrosive effects on glass. I put much larger amounts of stronger solutions of much more corrosive chemicals in my drinking glasses every day, and then scrub them with relatively harsh cleaning compounds, and none of them seem to have suffered any ill effects from it.
For the most part, the same will go for plastics, though it might depend to some degree on what type of plastic.
Glass is also highly corrosion resistant - that’s why many strong acids are stored in glass containers. If you’re sweating hydrofluoric acid, you probably have bigger problems than the state of your touchscreen.
Under the right circumstances, which yo aren’t likely to encounter in everyday life.
When I first started growing laser crystals in grad school, I used a high-temperature glass for my crucibles. After one crystal growth, I was astonished to find my fingerprints etched into the surface. The very high temperature of my crystal oven (700 to 900 C) wasn’t high enough to melt the crucible, but was hot enough to allow the stuff in my sweat to interact with the glass. And my hands weren’t noticeably sweaty – it was simply the normal amount found on unstressed hands in a comfortable climate.
That’s when I learned that real crystal-pullers used alumina crucibles, which don’t etch (Al[sub]2[/sub]O[sub]3[/sub] )
This is also why you are not supposed to touch quartz=halogen lamps.
that’s BOB (baked on biomatter)
If this was the case then seaglass could not exist. Sweat is mostly water and salt. I have found intact glass bottles at the beach that were over 100 years old! So no, sweat does not harm glass.
No, in my case the material was not baked on. It was clearly etched into the glass. I believe that’s the case with quartz halogen bulbs, too.