Daguerreotype Process
French · Daguerreotype 1839–1860
A polished silver mirror holding an image that appears and disappears as you tilt it. The daguerreotype is not a print on paper — it is a unique object, with no negative, and it cannot be copied.
Origin
Louis Daguerre, working from Nicéphore Niépce's earlier heliography, announced the process in 1839, and the French government bought it and released it free to the world — except in Britain, where Daguerre had patented it separately. It spread with astonishing speed: within two years there were commercial portrait studios in most major cities, and the exposure time fell from minutes to seconds as lenses and chemistry improved.
Technique
A copper plate is silver-plated, polished to a flawless mirror, and sensitised over iodine vapour to form light-sensitive silver iodide. After exposure the latent image is developed over heated mercury vapour, which condenses on the exposed areas to form a whitish amalgam, then fixed with salt or hypo and often gilded with gold chloride to strengthen and protect it. The mercury is the dangerous part, and it was inhaled routinely in unventilated studios. The plate is then sealed under glass, because the surface is so delicate that a fingertip destroys it.
The palette
Not colour but a physical optical effect. The image is formed by the difference between mirror-polished silver, which reads as black when it reflects a dark surround, and the scattering amalgam, which reads as white. Tilt the plate and it flips to a negative. The tonal range is exceptional — finer than almost anything since — and the surface has a faint blue-grey or warm cast depending on gilding. Many were hand-coloured with dry pigment on the cheeks and gold on jewellery.
Legacy
It made the portrait available outside the wealthy class for the first time, and the surviving plates are the earliest photographic record of human faces. Its fatal commercial limitation was uniqueness: you could not make copies. The negative-positive systems that followed were technically inferior in resolution and won anyway, which is a pattern that recurs throughout this domain.
Palette
The colours reconstructed for this artist, with the reasoning behind each.
Pigments used: Silver