Daguerreotype of a woman, c 1845.
© National Media Museum / Science & Society Picture Library
A hand-coloured daguerreotype portrait of a woman, taken by an unknown photographer in about 1845. The colour has been rather liberally applied to her cheeks, making her look as if she is blushing. In 1839, the Daguerreotype, invented by Louis Jacques Mande Daguerre [1787-1851], became the first photographic process to be announced to the public. Daguerreotypes are unique images which may appear positive or negative, depending on how light hits the surface. A highly-polished silver surface on a copper plate was sensitised to light by exposing it to iodine fumes. After exposing the plate in a camera it was developed with mercury vapour.