Admirals - Wet And Dry Identification

from BNAPS.ORG site
https://bnaps.org/ore/VanSomeren-Ad...ps-Intro.htm

1. Wet Printing
Between December 1911 and December 1922, all the Admiral stamps were printed by the wet printing method. The sheet of paper was dampened with water before the stamps were printed. When the paper was dampened, it absorbed water and expanded primarily in one direction, across the grain of the paper. After printing, the dampened paper was allowed to dry. As it did so, the paper shrank back to its original size. As a result, the stamps on the sheet shrank about a half millimeter in size across the grain.

After the sheet was dry, it was gummed, guillotined into panes, and perforated.

2. Dry Printing
Technological advances made it possible to print stamps on dry pre-gummed paper by using greater pressure. Eventually all denominations current as of December 1922 and later were printed by this method.

So putting pressure on the paper would "emboss" the image and you could see it from the reversed. Think of the Lawyers that would sometimes "Emboss" their seal on legal documents. Same idea.

Trodent

Thanks Trodent. Great explanation - more clear to me now.