I have my late grandpa's silver spoon attached to my fridge with a neodymium magnet. What kind of chemical reaction causes that discolouration?
this post was submitted on 15 Feb 2026
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I recall reading something about titanium and its color. The thickness of the surface layer determines the color. It’s just nanometers thick, but that means light begins to do weird stuff at that scale. I suspect the same applies to the silver oxide/sulfide/whatever layer on the spoon. If that’s the case, you’re not actually seeing the color of the surface layer. The layer is exactly the right thickness that specific wavelengths of light get reflected back while others don’t.
Proper physicists can add more details.
Thin film interference
Thanks!
Based on the phase interaction part of the article, there’s constructive and reconstructive phase interaction going on. That chapter has some nice diagrams about it.
That’s what produces the different colors. The thickness of the layer determines which wavelengths are lucky enough to reflect this way.
Also, here’s what happens with iron oxide.