In printing, a key plate is the plate which prints the detail in an image.
When printing color images by combining multiple colors of inks, the colored inks usually do not contain much image detail. The key plate, which is usually impressed using black ink, provides the lines and/or contrast of the image.
However, in two-color images where neither color was black, the key plate might have been printed in the darker of the two colors.
Key plate is synonymous with keystone in the same context.
Famous quotes containing the words key and/or plate:
“Woe to you lawyers! For you have taken away the key of knowledge; you did not enter yourselves, and you hindered those who were entering.”
—Bible: New Testament, Luke 11:52.
“I sometimes have the sense that I live my life as a writer with my nose pressed against the wide, shiny plate glass window of the “mainstream” culture. The world seems full of straight, large-circulation, slick periodicals which wouldn’t think of reviewing my book and bookstores which will never order it.”
—Jan Clausen (b. 1943)