The National Bank Note Co. 1870 portrait series was a direct consequence of changing presidential administrations and the unpopularity of the 1869 Pictorial stamps. The 1869’s were contracted during the Johnson administration by PMG Alexander W. Randall, but the stamps were not issued until after Grant took office on March 4, 1869. Perhaps in an effort to distance the new administration from blame for the 1869’s, Grant’s postmaster general, Jonathan A. J. Creswell, arranged for National to issue new stamps in the traditional portrait style.
In his 1870 report PMG Creswell states that "The adhesive stamp adopted by my predecessor in 1869, having failed to give satisfaction to the public, on account of their small size, their unshapely form [required the P.O. Dept.] to issue new stamps of larger size, superior quality of gum and new sizes...and to adopt for designs the heads, in profile, of distinguished deceased Americans..."
National’s contract ran until February 1873. Despite protests from other security printers, the contract for the 1870 stamps was not re-opened to competition. In common with the preceding two issues, the new stamps were grilled to prevent re-use, and this may have helped National to keep the contract. The G Grill used on the 1869’s was discarded. The 1870 Grills are identified by philatelists as H and I Grills. The H Grill is found on all values, and it is typically faintly or partly impressed. The I Grill has been recorded on the 1c, 2c, 3c, 6c, 7c and 15c stamps and is generally a stronger grill.
Many 1870 grilled stamps have extremely faint grills. The weak impressions could have been the result of faulty equipment, such as a worn and ineffective griller. There is also the possibility that National met its contract requirements by grilling every sheet delivered, but multiple sheets were fed through the grilling machine at once, causing weaker impressions in the sheets further away from the grill points.
It is likely that the practice of grilling stamps was abandoned during production of the 1870 Issue, possibly with the winking consent of a postal official. The ungrilled 1870 National stamps (Scott 145-155) are regarded by philatelists as a separate issue, but in fact they were produced under the same contract. Calvet M. Hahn analyzed the 1870 National Issue in an informative article in the Collector’s Club Philatelist (Sept.-Oct. 1989, pp. 297-333) and offered his hypothesis that all 1870 National stamps are grilled, and the absence of a grill is simply a factor of quality control. Other experts disagree with this concept and firmly believe that the majority of stamps issued by National between 1870 and 1873 were never fed through the grilling machine.
In 1873 the Continental Bank Note Co. was awarded the contract to print United States stamps. The National contract was extended until May 31, 1873, probably to allow time for Continental to find fireproof quarters for printing the stamps. A suitable premises was found on the top floor of The Equitable Life Insurance Company building in New York, on Broadway and Cedar Streets.
The National plates, dies and transfer rolls were turned over to Continental, who made new plates of the lower denominations. With the new contract Charles F. Steel moved to Continental on retainer. A small number of Continental stamps exist with the JGrill, but they are believed to have been made experimentally in 1876 after a stamp-cleaning court trial renewed fears of stamp reuse. The Worthington collection, which contained some grill essay material, was the primary source of the Continental JGrill stamps.
The Continental 1873 Issue was printed in nearly identical shades on the same paper used for the 1870 National printing. The presence of minute marks in the designs of most values enable collectors to distinguish the Continental stamps from their National counterparts. These tiny modifications are known as secret marks. It is likely that the secret marks were added to the transfer rolls or dies by Continental before laying out the new plates, to distinguish their work from National printings. A large die proof of the 1c was offered in the Caspary sale (Nov. 21, 1956, lot 557) with the notation "Secret marks put on by Chas. Skinner." Charles Skinner was never an employee of National.
Secret marks have been identified on the 1c through 15c stamps. The higher-value dies were marked, but the original National plates were used for printing. In the past few years a secret mark was discovered in the 30c stamp, and there is a possibility that the 24c and 90c Continentals have secret marks that have so far eluded detection.
Identification of Continental stamps is difficult on certain values, such as the 90c, which is distinguished from the National printing only by the slightly brighter, rosier shade. It is impossible to separate 24c stamps by printer, because there is no identifiable secret mark or consistent shade that distinguishes the 24c Continental from National. One 24c stamp is known on ribbed paper, which was used only by Continental, and the Scott 164 listing was reinstated on the basis of this stamp. However, Scott 164 is the only listing in the Scott Catalogue that is identical to another listing, Scott 153. In other words, any 24c stamp meets the characteristics assigned to both Scott 153 and 164, and there is no means to disqualify a 24c stamp offered as Scott 164. For this reason, the Zoellner collection excludes Scott 164 as a redundant listing, although the 24c ribbed paper stamp is indeed an interesting variety.