There is considerable debate these days as to what is and what isn't a test stamp. Generally they are issued by one of the firms who print stamps or stamp affixing machines.

   In the old days that included vendors who made vending machines that dispensed stamps. Since the Post Office wouldn't just pony up a few hundred rolls of 1 cent stamps to test those machines a whole additional world of collecting started for US and foreign stamp collectors - but bring your walletts. Most of the stamps are priced $20 to $3100 prior to 1927.

        If you want to get an overview of most of the recognized test stamps please refer to the Scotts Specialized Catalog of United States Stamps & Covers 2008 edition pages 763 thru 775. There you will find 138 photos or illustration of test coils and booklets. Sincere congratulations to editor James Kloetzel for expanding this catagory several years ago. This used to just be an annoying speed bump on the stamp collection highway.

    Since 1927 you will find over 40 test coils and 4 test booklet panes priced by Scotts at $20 or under. The modern test coils are printed by a wide variety of firms. They include: Bureau of Printing/Engraving, Multipost mailMaster, Avery-Dennison, SSP-Sennett Security Products, Ashton-Potter, Rena Systems, Banknote Corp of America, Martin Marietta, American Bank Note Co, Stampmasters Inc, Pitney Bowes, NCR and 3M

   Another fun aspect of the Test Coil series are the defacement lines which were issued in the  1960s to test various precancelling and taggent affixing machines. Those defacement lines were found in every color under the rainbow and in format from tiny uniform bars to chalky crayon-like lines. Fakes of these (I think they were silver) have been found at least once on ebay.

  The latest area of test-dummy stamps are the ATM test sheetlets, which have been used to test the chartridges they load with $20 bills and have been starting to offer sheetlets of 29/32/33/34/39/42 cent stamps at your nearest ATM. Du to the thinness of our money it poses a real challenge to get a sheetlet of stamps printed so they are the same consitency of paper money, yet do their job as a sheet of stamps. Avery-Dennison has been doing most of the reasearch in this area.

 Ebay is a great place to buy or sell Test-dummy stamps. It is a great alternative when you have collected 20th century stamps, back of the book, possessions or plate number coils. Welcome aboard - the water is great...but bring your wallet.

Note (Oct.2008) I have just heard that the new 2009 US Specialized Scott's catalog has been released with several major price changes. Some previously unpriced test booklet panes like TDB89A the George Clinton pane is now priced at $35.00. These changes may push some new items onto the market which should make the next few months interesting.