Albumin plate
Albumin plates are a technique that was used in early photography from around 1847. The albumin paper developed from this technique .
Albumin plates use glass as a substrate for light-sensitive silver salts. Paper was unsuitable for this in the middle of the 19th century, as it had an irregular fiber structure. The development of the albumin plate can be traced back to Abel Niépce de Saint-Victor . He covered glass plates with fresh egg white, which was whipped into foam and then liquefied again by standing for a long time. After adding potassium iodide, the plate was bathed in a silver nitrate solution so that the plate became photosensitive.
Albumin plates made it possible to produce negatives that came close to the brilliance of daguerreotypes . However, albumin plates showed only a low sensitivity to light. When using a lens with a long focal length and a speed of f / 72, for example, the British-Venetian photographer Felice Beato , who photographed the great uprising in India on albumin plates in the 1850s , still needed up to three hours of exposure time . However, Beato succeeded in reducing this time to four seconds by developing the plate in a saturated gallic acid solution for several hours . Beato did not publish this technique until 1886, when photography with albumin plates was already obsolete.