The collotype plate is made by coating a plate of glass or metal with a substrate composed of gelatin or other colloid and hardening it. Then it is coated with a thick coat of dichromated gelatine and dried carefully at a controlled temperature (a little over 50 degrees Celsius) so it 'reticulates' or breaks up into a finely grained pattern when washed later in approximately 16 °C water. The plate is then exposed in contact with the negative using an ultraviolet (UV) light source which changes the ability of the exposed gelatine to absorb water later. The plate is developed by carefully washing out the dichromate salt and dried without heat. The plate is left in a cool dry place to cure for 24 hours before using it to print.
To produce prints, the plate is dampened with a glycerine/water mixture which is slightly acidic , then blotted before inking with collotype ink using a leather or velvet roller. A hard finished paper such as Bristol, is then put on top of the plate and covered with a tympan before being printed typically using a hand proof press. Collotypes are printed using less pressure than is used in printing intaglio, or stone lithography. While it is possible to print by hand using a roller or brayer, an acceptable consistency of pressure and even distribution of ink is most effectively achieved using a press.
Because of its ability to print fine detail, it was also used for business cards and invitations with fine script lettering.
High-End Specialist Polishes its Reputation: Founded in 1947 to exploit a 19th century imaging process, Black Box Collotype of Chicago is moving into its next era of operation.
Nov 01, 2001; Black Box collotype is a 54year-old printing company that reproduces fine art for nearly all of Chicago's museums and many...
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Apr 06, 2012; THINK of Henry Moore and the chances are you'll picture one of two things - an enigmatic reclining figure or pages from his...