The Kodak verifax is a photo copying approach that uses a wet colloidal diffusion transfer technique patented by Yutzy, H.C. and Yackel, E.C. (1947)
The light source is projected to the top crossing the negative being reflected -more or less, according to the color- against the original to be copied exposing the negative. Has a base that contains the recipient with the
liquid developer and the exposure
timer
A timer is a specialized type of clock used for measuring specific time intervals.
Timers can be categorized into two main types.
The word "timer" is usually reserved for devices that counts down from a specified time interval, while devices th ...
.
Due to its extreme simplicity, the method was commonplace until the late 1960s, when it was surpassed by the popularity of the
xerocopies using plain paper. Copies had some chemical smell and lost contrast over time.
Diffusion transfer
The DT (Diffusion transfer) was widespread in several countries since 1960:
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* CopyRapid Agfa;
* Gevacopy of Gevaert (1950);
* Verifax Kodak (1952-1976);Polaroid
Polaroid may refer to:
* Polaroid Corporation, an American company known for its instant film and cameras
* Polaroid camera, a brand of instant camera formerly produced by Polaroid Corporation
* Polaroid film, instant film, and photographs
* Polar ...
, sepia (1948), id, White Black (1950), id, color (1963)...
Process
*The original sheet to be copied is placed face-down against the shiny side of a sheet of translucent
In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions a ...
sensitized "negative matrix" paper, then placed with the matte side of the matrix paper against the glass.
*The papers are exposed to light
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...
(not infrared) for about 15 seconds, where shorter exposure darkens the copy, and longer exposure lightens it.
*The original sheet is removed, and the matrix paper is immersed into the developing solution for 30 seconds, then extracted by pulling it out through pressure rollers, finishing the negative.
*This wet negative is pressed against a sheet of sensitized copy paper, and fed back through the rollers, giving gentle pressure.
*Finally, the two sheets are peeled apart, obtaining a slightly damp copy of the original, that has to lay on some surface while waiting to dry-out.
See also
* Light table
* Photo mask
* Diazo copier
* Photolith
A photolith film is a transparent film, made with some sort of transparent plastic (formerly made of acetate). Nowadays, with the use of laser printers and computers, the photolith film can be based on polyester, vegetable paper or laser film pa ...
* Thermal Copier A thermal copier or thermocopier (used as a Tattoo transfer copier) is a kind of photocopi er based on the effect of heat. The original sheet feeds in conjunction with the "thermo-sensitive" paper, generating a copy on its specially treated surfa ...
References
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Printing
Photographic processes