If you check the Scott catalog, youíll find listings for Wet and Dry printings for certain stamps issued during the 1950s. What are they and how are they different?
Intaglio printing involves picking up ink from recessed areas of a printing plate. Up until the 1950s, The Bureau of Engraving and Printing used paper that had between 15% to 35% moisture content. The paper was more damp (wet) so that it would do a better job picking up the ink from the recesses of the printing plate. One problem with wet printed stamps is that as the paper dried, it would shrink unevenly. The outer edges of the paper would shrink more than the inner portions of the paper. This uneven shrinkage caused problems when the stamps were perforated. Thatís why full panes of stamps on early US stamps usually exhibit a wide range of centering throughout the sheet. Some stamps may be VF while others would barely make an AVE grade. It all depended on how the paper shrank. And the BEP would sometimes have a high amount of scrap and would have to destroy large quantities of stamps.
Starting in 1953, the BEP moved to paper stock that contained about 5% to 10% moisture content. However, to get a quality printing job, the paper was thicker, the inks had to dry faster, and the printing presses had to operate with more pressure to force the paper into the recesses of the printing plate to pick up the ink. The result was that the paper didnít shrink as much, the perforations were applied much more uniformly, and there was less spoilage. It was a way for the BEP to increase efficiency and reduce costs.
How do you tell the difference between wet and dry printed stamps? Here are some general tips.
Wet printed stamps are on thinner paper. If youíre able to compare wet and dry printed stamps together, you can feel the thickness of a dry printed stamp compared to a wet printed stamp.
The other major difference is in the details of the stamp. With wet printed stamps, fine details (like the small dots used for backgrounds) are a little more blurry. Wet printed stamps often appear darker in color. Sometimes the paper appears to be lightly toned in the same color of ink as used to print the stamps. The fine details on dry printed stamps are more crisp and clear. The paper on dry printed stamps appears whiter in color.