Collodion wet plate negatives

Gelatin dry plate negatives

Albumen silver photographs

EARLY PHOTOGRAPHIC TECHNIQUES

Photography was not invented as such, but rather evolved from a series of developments in the study of optics, chemistry and the interaction of metals with light. By the 1830s scientific advances in these fields made it possible for an image to be captured and made permanent. In 1839 Louis-Jacques-Mandé Daguerre announced his daguerreotype process, which created an image directly onto a silver plated copper sheet. Soon afterwards, William Henry Fox Talbot patented another photographic process in 1841 - the calotype. The calotype was a paper negative which could then be used to create a number of photographic prints known as salted paper prints. Both processes remained popular until the 1850s. Daguerreotypes were particularly suited to studio portraiture and yielded a highly detailed image which was protected by a decorative case.

In 1851 the new ambrotype process was published and replaced the daguerreoptye in the late 1850s as a faster and cheaper alternative. Ambrotypes were also enclosed in a decorative case but the image was formed on glass, which does not have the highly reflective quality of the daguerreotype. The tintype, or ferrotype, was derived from the ambrotype process but created its image on a thin sheet of iron coated with black or brown lacquer. It was quite inexpensive and did not require the protective case needed for ambrotypes and daguerreotypes. For these reasons the tintype remained popular for portraiture from the 1850s until the end of the nineteenth century.

The greatest revolution in photographic processes came in 1850 and 1851 when glass plate negatives and albumen silver printing-out paper were introduced. Collodion wet plate negatives were first announced by F. Scott Archer in 1851. These negatives had several advantages over the earlier processes and soon superceded the calotype and daguerreotype. Wet plate negatives were highly detailed and required shorter exposure times than earlier methods - from a few seconds to a few minutes depending on the light. Most importantly, they could be used to produce unlimited numbers of albumen prints. The albumen print had been invented in 1850 by Louis-Desiré Blanquart-Evrard and became the most prevalent method for creating photographic prints from glass negatives. It yielded a much clearer picture than the earlier salted paper version and remained popular until the 1890s.

Captain Sweet worked with wet plate negatives and albumen silver paper for most of his career. In 1880 he introduced dry plate negatives to South Australia. Dry plates, which had been invented in 1871 by Richard Maddock, were glass plates coated with a gelatin emulsion of silver salts. They did away with all the messy chemicals of wet plate negatives, were far easier to use and much more sensitive, requiring shorter exposure times. Glass plates continued to be used into the early twentieth century, when nitrocellulose roll film became generally available.

The three processes that Captain Sweet used are explained in more detail via the links on the left of this page. Mrs Sweet continued to use dry plates and albumen silver printing-out paper until she closed the business in 1892.

© Karen Magee 2008 - 2009