How daguerreotypes were made
Unlike conventional photographs, daguerreotypes are metallic objects: copper plates coated with a thin layer of highly polished silver that can be viewed either as negatives or positives. The image consists of particles of a silver-mercury amalgam upon this reflective surface. Their submicron size ensures a very high optical resolution. The daguerreotype process directly creates a positive image, so these unique objects cannot be directly reproduced other than by photographing them.
As we has announced in the past news A Video on a Daguerreotypist Set, the Daguerreobase Project and the Museo FirST - Firenze Scienza e Tecnica produced a video. It shows an original daguerreotype camera with a lens manufactured by the Parisian optical firm Lerebours et Secretan around 1850. This equipment belongs to the collection of the Physics Cabinet of the museum of the Fondazione Scienza e Tecnica in Florence. It is accompanied by a typical daguerreotype kit including a tripod, a box for treatment with mercury vapor, boxes for fuming with iodine and bromine, a soft buckskin pad for buffing the plates and a box of unexposed silvered copper plates ready for use.
The silver layer of daguerreotypes is particularly prone to tarnishing due to oxidization and air pollutants, which can completely darken the image, and is easily damaged by wear and tear, although a gold-toning process protects it from abrasion and corrosion. In his manual Daguerre himself advised sealing daguerreotypes under glass to preserve their delicate surface, and a protective mounting was essential to ensure their long term preservation. They were therefore kept inside cases, coverings and frames that were commercially available in a wide variety ofmaterials, often with refined aesthetic qualities, inspired by the traditional mountings of miniature paintings, with some stylistic variations between Continental Europe, Britain and America.