Intaglio Printing Used In Off-Center Stamps
Earlier this week, Linn's Stamp News reported that it had spoken with a representative from the U.S. Postal Service (USPS) about a commemorative reprisal of classic-era U.S. stamps that were released last summer. According to Linn's, the 19th-century stamps were targeted for stamp collectors and were only available from the Stamp Fulfillment Services mail-order center in Kansas CIty, Mo. However, it wasn't the classic design of the stamps that made them stand out; it was the fact that they were off-center, noticeably off-center. When printing processes are as advanced as they are, off-center stamps of this magnitude would be highly unusual.
Linn's contacted Roy Betts, a spokesman in the Postal Service's corporate communications department, to understand better how this could have happened. It turns out that it was intentional. Intaglio printing — a traditional printing process that is still used to create some government items, such as banknotes and passports, but is rarely employed when printing stamps — was used for the commemorative stamps to mimic the less precise nature of stamps of that era.
Linn's received this quote from Betts:
“The intaglio process introduces extreme pressure during the printing process that can cause distortion of the sheet during print production. This distortion can vary through the production run.
“The equipment used to diecut this stamp issue is the same equipment that is used to process billions of stamps annually. The variation in the movement of the diecut is insignificant, thus producing stamps that are well-centered.
“However, 99% of stamps produced are printed in offset, which does not introduce distortion in the sheet, therefore allowing for well-centered, diecut stamps.
“The distortion that the intaglio process introduces appears to cause the diecut centering to be off but, in reality, it is the distortion of the stamps themselves that are causing the variation.
“The engravings for the Classics [Forever] stamps were created from actual stamp specimens curated from the [National] Postal Museum. The stamps themselves were different sizes, which also affects the appearance of the centering.”
Linn's received an even more detailed explanation to determine if the distortion was taken into account because of the pressure corresponding with the intaglio printing process. Apparently, the process necessitates planning for the distortion and, in turn, diecutting tools are ordered accordingly. USPS went on to inform Linn's that although the diecutting tools were ordered after the stamp production was underway to ensure accuracy, various elements, such as changes in the moisture content of the raw materials, can cause distortion.
Although some stamp errors are collector's items due to their rarity, Linn's reports that collectors should try finding sets that are centered.