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Frederick Scott Archer: Wet Collodion Photographic Process for glass negatives 1851
Scott-Archer’s genius was to amalgamate the best features of the two competing photographic
systems of his time - Fox Talbot’s Calotype and Daguerre’s Daguerreotype - and to speed up the
exposure time as well! His Wet Collodion Process dispensed with the foggy paper negatives espoused
by Talbot. He used glass as a negative substrate, and solved the problem that deterred Talbot and
others - the issue of getting photo-sensitive chemicals to adhere to glass. “For his experiments Archer
used collodion—a newly-discovered substance which was used as a medical dressing. A sticky
solution of gun cotton in ether, collodion dried quickly to produce a tough, transparent, waterproof
film. The process he discovered was to coat a glass plate with collodion mixed with potassium iodide
and then immerse the plate in a sensitising solution of silver nitrate. Exposed in the camera while still
wet, the plate was then developed and fixed immediately. Crisp, detailed negatives were produced by
exposures of only a few seconds.”( http://www.frederickscottarcher.com/Processes.aspx)
There was a downside however - the glass plate had to be prepared in advance for each session - and
importantly used while still ‘wet’ (ie before the collodion dried), which implied and enforced a different
methodology - an up to twenty-minutes of preparation time after the shot had been set-up, the camera
focussed, the sitter holding her or her pose...
The upside was an image as sharp as a Daguerreotype, it was a negative, and as reproducible as a
Calotype (Wet Collodion is a negative-positive process, but the plates themselves, angled to the light,
can be viewed as a positive).