Difference between revisions of "Ambrotype"
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| − | * [http://en.wikipedia.org/wiki/Ambrotype Wikipedia: Ambrotype] | + | * [http://en.wikipedia.org/wiki/Ambrotype Wikipedia: Ambrotype] - apparently wrongly attributes the invention to Cutting, [http://www.google.com/patents?id=9wcdAAAAEBAJ&printsec=abstract&zoom=4&dq=ambrotype+1854 whose patent]] only mentions the varnish or balsam back coating. |
[[Category: Photographic processes]] | [[Category: Photographic processes]] | ||
Revision as of 01:27, 29 August 2008
Ambrotype is a photographic process resulting in positives on glass, originated by Frederick Scott Archer and Peter W Fry in 1851[1]. It was intended as a cheaper alternative to the Daguerreotype. It is based on the wet-collodion process. It was also known, in Britain, as "collodion positive", and in other places as "Melainotype".
Glass plates are prepared, and developed as in the wet-collodion process, but underexposed. This gives a less dark glass negative, which is mounted in a metal frame with a black background. The background makes the negative appear positive - as the black (silvered) areas reflect light, and the transparent areas show the black background. The back was sometimes varnished or coated with balsam to improve the image; James Ambrose Cutting of Boston was granted a US patent in 1854[2] on a method of doing this - which makes the image "greatly increased in strength and beauty by imparting additional brilliancy".
Ambrotypes were often hand-tinted to increase the contrast; without this, Ambrotypes are grayish-white and compare poorly to Daguerreotypes.
- ↑ Focal Encyclopedia of Photography, Focal Press, 1976 edition, p.40
- ↑ US Patent 11,267: Improvement in Photographic Pictures on Glass
- Wikipedia: Ambrotype - apparently wrongly attributes the invention to Cutting, whose patent] only mentions the varnish or balsam back coating.
