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:
“Experience has shown that the trade of the East is the key to national wealth and influence.”
—Chester A. Arthur (1829–1886)
“Our press is certainly bankrupt in the “thrill of awe”Motherwise reverence: reverence for nickel plate and brummagem. Let us sincerely hope that this fact will remain a fact forever; for to my mind a discriminating irreverence is the creator and protector of human liberty.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)