80 Years Ago in STAMPS: Patented Means to Prevent Re-Use of Stamps.

The article explores different patented methods developed during the Civil War era to prevent the re-use of stamps. These methods included breaking the paper, gumming transparent paper, tearing off a portion of the stamp, printing in alkali ink on acid ink-sensitized paper, applying pulverized starch or water color pigment, incorporating ingredients that would produce a stain under moisture, and using fugitive ink that would wash off when wet. However, these methods were experimental and not widely used for postal purposes. The article also discusses patents for punch cancellations, prick cancellations, invisible cancellations, and eight-hole stamps, as well as the National Bank Note Company's idea of printing stamps in different colors for better visibility. The text includes specific patents and images of stamps, and also promotes various publications and offers for stamp collectors. [Extracted from the article]