***Auction Highlight*** 1935A **Rare Experimental Red S Overprint** $1 Blue Seal Silver Certificate Grades vf++. Rarely seen "S" Experimental Blue Seal US Silver Certificate. It was rumored that in testing these notes, a red R was overprinted on the regular paper and a red S was overprinted on the special paper. However, recently sources have confirmed that the "R" actually stands for Rayon and these are the experimental notes, while "S" means Silk. During WWII a lot of silk was needed to make parachutes. So it was likely this was a wartime experiment to replace the silk threads used in US currency. Both R & S notes were delivered June 20th 1944 and issued into circulation to test their respective durability. No conclusive results were determined from the experimental issue. Still a very interesting artifact of numismatic history! A Key Date's Pick