So I have this pepper shaker made of glass with a print on it:
One fine dinner, it ran out of pepper, so I opened the lid to fill it up and noticed a peculiar thing – small particles of pepper dust were stuck to the inside glass walls but only in places where the print wasn’t present on the other side. Everywhere directly behind the print, the pepper particles almost didn’t stick to the glass.
(These photos also show vertical traces from a spoon, which are not relevant, I hope you’ll see the phenomenon anyway.)
I’ve been wondering about this for a while now and been thinking whether it’s got to do with light, or light and humidity, or different heat transfer, or electric charge… But as for now, I don’t have the final answer, and I'm looking for possible explanations of this phenomenon in the world of physics. This item is standing in an open space, so it is exposed to daylight, at times even a significant amount. Most of the time it is placed on a shelf above a gas kitchen stove, so it might be also getting some increased amount of humidity and heat.
Perhaps you know ways in which it could be explained, or you know a paper that studied similar effect experimentally? I would love to gather some clues to solve this mystery.