An unscreened photo-mechanical printing block, normally of zinc (zinco), which is used as a 'master' for the requisite number of 'electros' or 'stereos' from which stamps are printed by the letterpress, typographic, or surface method.  For short runs, the original zinco may be used, and both the original block, and the copies may be steel, chromium, or nickel faced to resist wear.  It is also used (in the U.S.A. especially) to describe a block of stamps with either a vertical or horizontal line gap running between rows of stamps or an inserted guide line for colour registration, perforating, or slitting.

Half-tone

Photo-mechanical printing process in which the tones of the original are represented by raised dots.  Rarely used for stamp printing but instances are: Uruguay 1908 Declaration of Independence set (centres only), and Kishengarh, India, 1913.
 
 

- R. J. Sutton 6th edition revised by K. W. Anthony
The Stamp Collector's Encyclopaedia

Published 1966

Posted February 21, 2000