User:Walkranrunning/Kodalith

Kodalith is the name given by Kodak Corporation to a high-contrast orthochromatic lithographic film that was discontinued in approximately 2006. It was widely used by the graphics arts and print industries, as well as occasionally for the distinctive photographic effects it could provide.

Kodalith was produced in 35mm, 4x5 and 8x10, and possibly other formats.

The high-contrast characteristic of Kodalith was almost magical to the new initiate. It conveyed virtually no shades of grey, its gamut of transmissivity abruptly switched from virtually transparent to a nearly opaque black, more so than was normally seen in black-and-white films. This high contrast also produced unusually pronounced contours in solarization.

Kodalith processing was relatively straightforward, being comprised of a basic three-bath process with developer, stop bath, and fixer. One unique aspect was the short life of the developer, which was supplied as a two-part system, with components A and B. The two parts were mixed together immediately before use, which had to occur within one hour  of mixing. Subsequent parts of the processing, the stop bath (acetic acid, dilute) and fixer were standard for black-and-white processing. Development was also characterized with D-11 chemistry, although this did not deliver the extreme contrast of which the film was capable.

Kodalith sensitivity was low relative to standard photographic films, ASA 8-12, but this was common for litho films, in which very high illumination levels were available. Kodalith's orthochromatic spectral sensitivity was also common in the industry. Because it was only sensitive to shorter wavelengths, this meant that it could be handled and processed in relatively bright red light; the Wratten 1A red safelight filter was the approved illumination during processing.

References:

Kodak Technical Reference: http://www.kpgraphics.com/service_support/downloads/support/online/ortho/ti/ti1105.pdf

See also: Fujilith, Ilford Ortho Plus

Kodalith photo examples: http://www.flickr.com/photos/ivanaguiar/sets/72157594557523178/