As a start, most collectors try to get one full sheet of each value or type. This is a fun but it is even more fun and challenging to specialize and collect ALL the different printing press sheets in a more limited area, such as the Rosette , large numeral, or OPD issues. Let's look at some basics for telling the different sheets apart, even if the stamp designs are the same.
The margins of the sheet contain a number of important identifying characteristics.
Top and Bottom field markings (above or below the stamp)
Advertising (right side)
HAN Numbers (bottom)
"form" numbers (usually bottom corners, usually)
Printer's marks (almost anyplace)
Perforated left or right side margins.
Two types of printing were used to print the sheets of the inflation period. The government printing offices had both flat plate and rotary printing presses available.
Flat Plate Printings:
The sheets printed in one operation have numbers across the top. These are the "row value numbers" (in German as "Reihenwertzahlen"). These, along with the numbers down the left side of the sheet ("Summierrungszahlen") aided the postal clerks in determining the remaining value of a partially sold sheet. On values that required two printings (rosettes, for one), horizontal strips of small vertical bars ("Strichleiste) or solid bars were sometimes placed across the top and bottom margins of the first printing. These reduced the printing pressure on the top and bottom stamp fields and reduced damage to the printing plates. The Row value numbers were added in the second press printing.
These protective bars give rise to three collecting varieties:
Type "A", no bar.
Type "B", horizontal bar of small vertical lines.
Type "C", horizontal, thin SOLID bar.
Fields 5 and 6 of the "B" margin often do not have the bars and appear to be type "A". Purists avoid collecting these fields since they can not be solidly identified as originating from a true "A" type sheet.
The plate plate printing press plates consist of 4 (2x2) counter sheets.
Rotary Press Printings:
The sheets from the rotary presses have vertical bars across the top and bottom of the sheet. Row value numbers are embedded in the line structure. There are usually 7 or 13 bars in both margins. Specialists even collect bar varieties. Sometimes the bars are short, sometimes extending down the margin around the row value number. A 13 bar margin with 3 bars extending down each side would be described as 3'7'3, one with 7 bars all short would be 0'7'0. Different bar structures can exist on the same sheet.
The modern rotary presses used, printed 8 (2x4) counter sheets at one time (8 sheets per rotation). Sheet counter numbers were printed in the center margins, between the counter sheets. After the press sheet was cut apart, a sheet counter number appears on the right side margin of the left printing sheet and on the left side of the right printing sheet. There are no other margin markings.
As the pressure increased to get stamps printed, the printers revived an old rotary press (actually the first one they had bought in 1908) and used it too. This old press only printed 2 sheets at a time so there is no "right" or " left printing sheet.
Flat on Rotary:
On two values of the Rosette issue (50 Million, 500,000 Million) the background was printed with the old rotary press and the value was printed with the flat plate press. These sheets have both rotary and plate plate margin markings. Special plates were used for the rotary background printing, there are 13 vertical lines in the margin. (The normal rotary printings had 7 lines) These examples are scarce, the OPD overprinted examples of these flat/rotary sheets are among the era's great rarities.
Some sheets do not have advertising, the margin is either blank or has a vertical row of small, horizontal bars (called "Strichelleiste"). Advertising first appeared in 1921 on the margins of the Small numeral, lozenges watermarked values. There are six different advertisement on the right hand margins.