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Wednesday, September 29, 2021
CONTINUITY: From 1959—“The Art of Gold Beating”: Making Gold Leaf
The thickness of gold leaf is around 100 nanometres, which is the wavelength of near infrared light and only around 2000 gold atoms thick. If you hold a sheet of gold leaf up to a bright light, you'll see light transmitted through it, with a shade of green-blue. I used to think this was an interference effect due to the thickness of the leaf, but it's simply a result of gold reflecting predominately red and green light, giving it its characteristic mellow glow (thanks to special relativity), with the unabsorbed blue and green wavelengths passing through the thin sheet.
Posted at September 29, 2021 11:56