The Daguerrotype process is a photographic process, which was the first practical
form of photography.
The process of the daguerrotype was made public in August of 1839, but as it
needed long exposure times, it was seldom able to produce portraits in its
earliest form. Around 1840, this obstacle was overcome by making the plates
more sensitive to light.
Daguerreotypes are often brown-toned, and have very shiny, mirrorlike
surfaces. They have exceptionally fragile surfaces and for this reason,
they were always kept behind glass in frames or small folding cases
A daguerreotype is made on a sheet of silver-plated copper. The silver
surface is polished to a mirror-like brilliance. The plate is then sensitized
over iodine vapor, exposed in the camera, and developed with mercury
vapor. By 1840, experimenters had succeeded at increasing the sensitivity
of the process by using chlorine or bromine fumes in addition to the iodine
vapor. The earliest daguerreotypes tend to have bluish or slate grey tones;
a brown-toning process called "gilding" came into widespread (but
not universal) use late in 1840.
Read more about Photographic Processes