What is silver plate photography?

Silverplate photography is a method of developing the exposed silver salt coating with mercury vapor, which was invented by Daguerre, the chief landscape painter of a famous Paris opera house, on 1839. The exposure time of this photography is about 30 minutes, which is much shorter than that of Nieps solar hardening photography. The photos taken by this method have the characteristics of thin shadow line, uniform tone, good fastness, unrepeatable and opposite images. This method of photography is named after the silver plate photography, so it is also called the silver plate photography. The specific steps of silver plating method are: preparing a copper plate plated with thin silver; Cleaning and polishing; In a small box filled with iodine solution or iodine crystal, iodine vapor reacts with silver to generate silver iodide. The time is 30 minutes. Transfer to a film box; The tapes are put into the black box for shooting, and the time is 15 ~ 30 minutes. Under the action of light, silver iodide is reduced to metallic silver with different densities according to the intensity of light, forming a "latent image", which is first developed with mercury vapor and then put into concentrated hot salt solution, and then "fixed" by the action of sodium chloride. Was with water and dry. In this way, an image formed of cream-white amalgam is obtained. The shaded part is transparent, and the dark silver-plated copper plate surface can be seen. It becomes a positive photo.