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In photogravure printing it is relatively easy to establish the direction of printing thanks to the fact that whilst the paper web/sheet moves away from the cylinders the ink particles flow in the opposite direction towards the cylinders. This direction towards the cylinders is called the direction of printing [imagine a fixed point on the paper where the print has started, the cylinders/press are moving away in that direction!]. The photogravure screen cells are usually full of ink and difficult to tell apart at the direction of printing side, often there is a drag of ink outside the image whereas at the opposite side the cells are well discernible and the image seems to fade. Occasionally little streams or waves can be seen in the larger printed areas. If they are horizontal the direction of printing will be either to the left or to the right, if vertical upwards or downwards. |
The four directions, always relative to a readible stamp, are denoted as follows:
The direction of printing in horizontal size commemoratives, and in the definitives is normally upwards [U], in vertical size commemoratives normally to the right [R]. |
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All photogravure stamps with watermarks have either direction of printing U or R according to their size. There is only one acception: The 1955 New Year 25pr has direction of printing L. Comparing this stamp with the 1956 New Year 30pr not only the direction of printing has turned 180 degrees: R, but also the absolute watermark position: f. instead of h. |
N.B. this effect had nothing to do with the way the web of paper had been fed into the printing press. The web of paper had been mounted as usual, only the printing cylinders had been mounted the other way around!!! |