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Errors Caused in Printing
In plate errors, it needs to be considered that printing plates, cylinders and clichés have to withstand high pressure and wear. When the material is worn, tears or bubbles may appear or a piece actually break away. Every such change will be immediately reflected in one or more stamps. Much depends on how quickly the error is detected and remedied.
When printing plates were originally grouped from individual clichés, and some fault occurred in one of the clichés, it was sufficient to replace the damaged cliché. As long as the cliché was produced from the original die everything was in order. Sometimes, a cliché was inserted upside down and a tete-beche reproduction resulted. There were also cases when a cliché was replaced by mistake, with a cliché of another stamp similar in appearance or of another value. This resulted in most interesting errors of colour and se-tenant stamps of different value.
With retouching, printing plates which are in one piece and in printing cylinders, it is impossible to change the damaged cliché. If a fault appears, the printers aim to correct it through retouching. With the help of a scorper, they re-engrave the blocked spots in order to try to remove the damaged areas. Even the smallest intervention of this nature changes, to some extent, the design of that particular stamp. In 1920, Czechoslovakia issued a set of definitives in two designs: the first was a dove carrying a letter in her beak and the second was an allegorical figure of a woman breaking her chains. The fifty heller stamp with the image of the chain-breaker was printed in red up to 1923, but from January 1922 to the end of 1925, it was also printed in green and the same printing plates as were used for the red stamps were used for the green. The thirty-ninth stamp in every sheet had a typical plate error – a white spot dubbed by philatelists as ‘The Egg in the Waist’. This error can be found on both coloured stamps.
Double impressions occur if a worker handling a printing press mistakenly puts a sheet through the press twice; each stamp shows two impressions quite distinctly. This error is seldom seen as faulty sheets are usually discovered by checkers and then eliminated and destroyed.
Inverted printing. When stamps are printed in two or more colours, another printing error sometimes occurs: the worker, when putting a sheet of stamps into the press for a second time to print another colour, turns it by 180 degrees, and the second colour becomes inverted. In 1918, the first air-mail stamps of the United States were printed. The highest value of the set, twenty-four cents, had a deep carmine frame and a blue centre. One sheet of this stamp was printed with an inverted centre so that the aeroplane was flying upside down. Only one hundred copies of this error exist and they are highly prized by philatelists.
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