The Secret Mark of the 15 Cent Banknote

Part 1: The Plate Wear Theory of Lester Brookman


 1.  Overview

When the Continental Bank Note Company (CBNC) took over the contract for printing the so-called “Banknote” stamps from the National Bank Note Company (NBNC) they made new plates from master dies that had been altered with “secret marks”.  However, new plates were not made for all denominations.  New plates, incorporating secret marks, were made for the lower denominations, at least through the 12¢ stamp, and while the master dies for the 24¢, 30¢ and 90¢ stamps were altered with secret marks Continental did not use these dies to make new plates.  These latter denominations were printed by CBNC using National’s old plates, thus none of these stamps displays a secret mark.

The secret mark for the 15¢ CBNC banknote has presented something of a mystery. A new plate was made by CNBC, plate 31, but it is not clear whether the master die was altered with a secret mark first.   According to some scholars, the secret mark is a line or lines that have been strengthened at the bottom of the triangular “coffer” at the upper left corner of the design (see left illustration below).  This mark, know as the “V”, was accepted by Scott Publishing as the 15¢ secret mark, and forms the basis of their catalog illustration to this day.  However, Lester Brookman in his The 19th Century Postage Stamps of the United States (1947) disputed that this “V” constitutes a secret mark.  He raises the possibility that people were led to believe it is a secret mark because of a lightening of the left bevel of the triangular “coffer” design element (below, at right) that frequently shows up on CBNC and American Bank Note Company (ABNC) printings, an anomaly which is never present on the earlier NBNC printings.

When this bevel is lighter it naturally makes the “V” more prominent, thus Brookman concluded people were led—falsely, in his opinion—to assert that the “V” constitutes the secret mark on the 15¢ banknote.  Brookman ascribed this lightened bevel to “plate wear” and quoted from Elliot Perry’s remarks that had been published in “Pat Paragraphs” in December 1936— 

“The fact is some lines on the die were cut less deeply than others . . . and as the plates wore the fine (shallower) lines tended to disappear.  Less color, therefore, is found wherever they wore away and this is why ‘white parts’ of the design ‘look whiter’ on some 15c orange stamps than on others.   Many such 15c Websters are undoubtedly from the Continental printing, but some are American prints . . .  As the finer lines wore away the stronger lines remaining in or near the ‘whiter’ areas tended to stand out by contrast.  This is noticeable in the areas of the so-called ‘secret mark’.  The two lines forming a sort of V . . . being sunk deeper on the plate, they became more prominent by contrast as the finer lines near them wore away.”

Brookman states that his opinions coincide “for the most part” with Perry’s, and goes on to assert that finer lines on the plate, as the plate wore, would show up lighter on the prints while darker lines (i.e. more deeply engraved) would show up darker. Unfortunately, as illustrated below, this belief does not stand up to scrutiny. 

2.  A Technical Examination of Plate Wear

Above (and below) are some examples of plate wear as seen on prints pulled from plates made by both Rembrandt van Rijn and Francisco Goya.  Neither artist was in the habit of canceling the etching plates from which they printed—canceling a plate involves destroying or defacing the surface in such a way that the plate cannot be used to create any further prints.  As a result these artists’ plates have been printed continuously by opportunists throughout the centuries following their deaths.  As could be expected, these printing plates began very early on to show evidence of wear, since the process of applying the ink then wiping it in preparation for printing is harsh, and abrades a little of the surface of the plate each time.

Comparing the two impressions of Rembrandt’s “The Three Trees” shows how all the features of the plate wear at the same rate.  The slanting rain lines at top left, and dark cloud lines at top, are deeply etched into the plate, yet they are considerably weaker in the later printing.  Lines that started out weaker are similarly compromised—in some cases at the far right they have almost disappeared altogether.  Even in the tree, the densest, most heavily drawn part of the image, the lines are not as strong as they were originally.

Not so subtle are the effects on the prints below, two examples from Francisco Goya, who relied heavily on the technique know as aquatint to produce the dramatic chiaroscuro (light vs. dark) effects on his prints.  The fact that plate wear has degraded these images, and the that this wear is consistent across the image, is beyond dispute.


3.  “Plate Wear” According to Perry/Brookman

Below left is an example, rendered in black and white in order to increase contrast, of what Lester Brookman illustrated as “plate wear”, on a card proof of Scott 163.  Beside it is the same area on a stamp which is unequivocally an American Bank Note Company 15¢ banknote, Scott 189, because of the thick, soft paper on which it is printed.  Both were printed from the same printing plate, known as plate 31.

On the left stamp, the 163 proof, the leftmost bevel of the triangle design is distinctly lighter than the top bevel.  By contrast, both bevels of the stamp at right are of nearly the same intensity. The left image shows what Lester Brookman described, and illustrated, as “plate wear”. Logically, then, it would follow that the left stamp would show plate wear all over it, while the right stamp would not.

But that is not the case. Examining both stamps at high magnification (below) reveals that the proof at left is a pristine impression, showing virtually no evidence of plate wear, while the stamp at right was printed well into the life of plate 31, when it was showing obvious signs of wear.


An examination of three areas in detail underscores the point.  First, the label with the word FIFTEEN.

Next, a comparison of the top of the head of the figure:

Last, the triangle design in the lower right corner:

It is not credible, based on the comparison above, that the lightened area of the triangle in the UL corner of the proof at left was due to any sort of plate wear.  If so, the entire proof would show a plate terribly worn down, which it clearly does not.  Also, Brookman’s assertion, that the lighter lines of an engraved design would become lighter as the plate wore while the darker lines would become darker, is simply not true.  Both Rembrandt’s “The Three Trees”, and the stamp at right immediately above, demonstrate beyond any doubt that darker lines suffer the same fate as lighter ones when plate wear sets in.  The entire image, and all individual aspects of it, become lighter as the surface of the plate is abraded through use.

 4.  Consistency in Examples of Perry/Brookman “Plate Wear”

The 15¢ banknote “plate wear” as defined and illustrated by Lester Brookman displays a certain rigid consistency, demonstrated below.


The white arrows show three generally distinct light areas in the left bevel of the triangle, while the black arrow shows a short full-strength line among the lightened ones.

It is remotely possible that a single relief on a printing plate can wear as unevenly as the example above, that is, so that the only worn spots appear in the left bevel of the triangle.  However all examples of Brookman’s “plate wear” show exactly this pattern.  Below are several examples, taken entirely at random from 15¢ banknotes that show the “plate wear” illustrated in Lester Brookman’s The 19th Century Postage Stamps of the United States. 

The three stamps in the top row are soft-paper 189s, on which the printing is somewhat fuzzier, while the bottom three examples are harder-paper 163s.  All six stamps show the three lightened areas and the one remaining dark line as noted above—a mathematical impossibility if all were from different reliefs on plate 31 and Brookman’s “plate wear” were a normal process of the lines breaking down across the plate.  Since the stamps above were chosen at random, the odds against all being by coincidence from the same position on plate 31 would be astronomical. (For further examples, Siegel’s online Powersearch, if used to find all examples of Scott 189 sold at their auctions, will show conclusively that the so-called plate wear described by Lester Brookman follows this distinct pattern to an extraordinary degree.)

5.  Conclusion

It is simply not possible that all positions on plate 31 that show the distinct “Brookman plate wear” were abraded in the exact same fashion all over the plate.  Such remarkable consistency can have had only one source: the “Brookman plate wear” must have been imparted to the plate by the transfer roll, which had been made from a master die that had been altered, either accidentally or deliberately, from its state when it was used to make the transfer roll for the National Bank Note Company’s 15¢ banknote plate. 

Furthermore, since there exist reliefs on plate 31 that without question do not show this “Brookman plate wear” it seems also inescapable that at least two different transfer rolls, made from two different states of the master die, were used to rock in the reliefs on the plate.

It is well established that Continental altered the master dies they received from National and either made new plates (1¢ through at least the 12¢ denominations) or continued to use the old National plates (24¢, 30¢ and 90¢ stamps).  Any theory that supposes they would alter all master dies except the 15¢ raises questions that are difficult to answer.  It is possible that the master die was altered for the production of plate 31 but the resulting secret mark proved too difficult to see, requiring further adjustment to the master die and the making of a new transfer roll; however that is a topic for another, separate inquiry.  It is enough, for the purpose of the current inquiry, to reiterate that the “plate wear” described and illustrated by Lester Brookman on pages 80-89 of the 1947 edition of his The 19th Century Postage Stamps of the United States has in fact nothing to do with how plate 31 wore during its long service printing 15¢ banknote stamps for both the Continental and American Bank Note Companies.