Identification by printer code
For their own records printers imprinted a job/card number. This could be a plain 3 to 6-digit number, a combination of numbers and letters and sometimes really unusual like in the case of E. Pinkau & Co, Leipzig and their “Capital Letter” and especially the “Dot & Dash” code (researched by George Webber). These codes are found usually on the address side, with few exceptions. Sometimes arranged inside stamp box and when postally used hidden below postage stamp. The illustration at top shows a “double-code” not often used back then. The 6-digit number is the card number of the printer C.G. Roeder, Leipzig. The number below belongs to the agency/jobber Otto Leder, Meissen, Saxony. The “07” stands for the year 1907, when the photograph/card was first published. Otto Leder, sometimes his initials O.L.M. also also found with code, arranged a number of cards for US and Canadian publishers as well as for other countries. Many printed by Roeder – but not always.
Numbers: Often not very exciting for research unless you have plenty of cards at hand (best from various countries) to compare and find enough identical arranged cards (size of number, font used, printing colours/styles) of which one might bear the printers name. Some printers used the same job/card number for reprints, others used a consecutive numbering and reprints always received a new number. (like C.G. Roeder, Leipzig, a big contract printer and widely researched in TPA by George Webber and others).
Some number codes reveal additional information and state the year the card was printed. Dr. Trenkler & Co., as well as collotype printers Glass & Tuscher, both from Leipzig, used year date codes for a longer period. Good for dating not postally used cards.
Sometimes card numbers show a a single letter prefix. This is often a production code for the quality / process or make. Generally found only on cards ordered by big customers who ordered different printing qualities from the same printer for a longer period. For a better internal organisation. Could be the other way too, that the printer used an prefix for specific customers or more likely a printing process, extra finish, hand-colouring or whatever.
General problems: Is the number found on a card a printer or a publisher card number? Was printer and publisher the same firm? What when there are two numbers around? There have been cases in the past when cards from the same printing source show numbers or codes, but others not. “Without” was usually done on customers demand who probably wanted his own codes to be listed only. As said before a number alone is rarely good for clear identification. Other layout elements as well as the printing style/quality or anything characteristic must be considered, too.