Ars Technica: Scientists found these old photographs contain metallic nanoparticles

Ars Technica: Scientists found these old photographs contain metallic nanoparticles. “Daguerreotypes are one of the earliest forms of photography, producing images on silver plates that look subtly different, depending on viewing angle. For instance they can appear positive or negative, or the colors can shift from bluish to brownish-red tones. Now an interdisciplinary team of scientists has discovered that these unusual optical effects are due to the presence of metallic nanoparticles in the plates. They described their findings in a new paper in the Proceedings of the National Academy of Sciences.”

TechCrunch: New technique brings secrets out of old daguerreotypes

TechCrunch: New technique brings secrets out of old daguerreotypes . “Daguerreotypes – photos made with a process that used mercury vapors on an iodine-sensitized silvered plate – break down quite easily. The result is a fogged plate that, more often that not, is completely ruined by time and mistreatment. However, researchers at Western University have created a system that uses synchrotrons and ‘rapid-scanning micro-X-ray fluorescence imaging’ to scan the plates for eight hours. The system shot an X-ray 10×10 microns thick at ‘an energy most sensitive to mercury absorption.’ This, in turn, showed the researchers where the mercury is most prevalent, thereby bringing up the image that was lost to damage or decay.”