Thanks for the info Glenn.
I also found out a bit about dry offset
From the Encyclopaedia Britannica
Dry offset, also called Letterset, or Indirect Relief Printing, offset printing process combining the characteristics of letterpress and offset.
A special plate prints directly onto the blanket of an offset press, and the blanket then offsets the image onto the paper.
The process is called dry offset because the plate is not dampened as it would be in the offset lithography process.
The process was developed by the U.S. Bureau of Engraving and Printing to produce long runs of tax stamps and savings bonds.
Which jives basically with Michel's introduction
regarding printing methods.
The German castles definitives where originally printed letterpress
(typography) but some values were
printed/reprinted in the late 1980s via letterset
Here is a link for pics of a Heidelberg Rotary Letterset or Dry Offset Press, Model KRZ - Germanyhttp://www.howardironworks.org/coll...rz-1964.html