High Denomination Banknote Questions

My understanding is that when Continental took over from National they did in fact make master dies with secret marks for the high denomination banknotes – 24c, 30c and 90c, but they did not use these to make new plates.

I can reference this link concerning the 15 cent 'betwixt-and-between' 15c: http://www.jamesdire.net/sm15bn.html. Bill Weiss also wrote a monograph on this stamp.

My questions, please: Is this information correct? If so, what is the primary source for the above article? Also, if so, were die proofs made – showing the secret marks – of the 24c, 30c and 90c?

I understand the only known Continental 24c is a ribbed paper. Has it sold since the Siegel 2004? https://siegelauctions.com/lots.php...8&page_no=11 also details history and recent findings.

Thank You

In the future it may be possible to better distinguish extant Continental 24 cent printings from National printings. For starters, there may be two populations of the stamp with different response characteristics to UV light. Some research using an XRF and other advanced equipment is underway. Also, a few examples exist with numerous small fibers (referred to as silk paper) similar to Continental silk paper. The problem is that Continental Silk paper is believed to have appeared after the 24 cent rate ended. However, no other National Bank Note stamps have this type of paper leaving the 24 cent silk paper stamps in limbo.

The problem with the 15 cent stamp does not have a "secret mark" as reported in the Scott catalog. Although the National printing is a paler orange, the color has more intensity compared to the somewhat deeper orange of the Continental printings. National printings show fine lines in the triangles while Continental printings have missing fine lines. But, the Continental ribbed paper printing shows the fine lines normally missing from other Continental printings. Finally, while the Continental Bank Note Company produced a new 15 cent plate, the National Bank Note Company plate was used initially. All of this suggests that the Continental Bank Note Company used a different ink formulation where the due components were not as finely ground.