Philatelic Terms Explained: Line Engraving
Britain's line engraved stamps are among the most popular in British philately and the very nature of the printing process means a huge number of subtle varieties and plate characteristics have been researched and catalogued over the years. As a result experienced stamp collectors can now trace individual stamps back to the exact printing plate used in it's manufacture and many collectors set themseleves the challenge of finding the stamps to reconstruct an entire printing plate.
Line engraving is a the process of engraving recessed lines in steel or copper to create the plates needed for so called recess printing. It is one of the oldest techniques associated with printing and was used in the production of banknotes as far back as the early 18th Century.
In the philatelic world the line engraving process was adapted for postage stamps by Perkins, Bacon and Petch who produced the world's first postage stamps in 1840 (The Penny Black). The design of these early british stamps was engraved in to a soft steel master die in recess (and reverse). Once complete the die was hardened using a chemical process and the resulting image transferred to a soft steel cylinder called, appropriately, the transfer roller. The roller was then hardened allowing the image to then be trasferred on to printing plates. Images on the final printing plates appear in reverse meaning the impressions made on paper appear correct.
In early line engraved printing the paper was often dampened to help force it in to the plate recesses for ink to be applied. This regularly caused problems when perforations were later introduced for stamps in the 1850s due to shrinkage as the paper dried. This explains the often poor centering of stamps from that period.
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