One of my side collections is US $1 small size currency. Right now I'm working on varieties. Here's two. US $1 1928A Experimental ZB Block Paper Test US $1 1935A Experimental "R" Overprint Paper Test
I'll see if I can keep this short. In 1933 for the 1928A and 1928B series the BEP was investigating the effects of relative amounts of linen and cotton (rag) content in the paper. The experiment using a portion of the XB and YB blocks which had different relative amounts while the ZB block was the control using the then current mix. I see nothing about the results. In 1944 a durability test was done with the SC block of the 1935A issue. The "R" overprint indicated regular paper. The "S" overprint indicated special paper. Again no conclusive results.
Super rough ! would say F-15 on a good day ! but still there really cool notes and not on every street corner !
I sold my R & S silver certificates long ago about 25 years ago, wish I had them now. They were about vf or so, picked them up for a song.
Do not want to step on anybody,s parade here but this note appears to be over graded to me, dont shoot me..LOL, but CGA had problems for years, even going back to the days with there involvement with "Arcade Currency" notes That have been graded after a change in mgmt/ownership they started putting Stars on the front of the notes to distinguish the old from the new. That,s stiil an awesome note though !! congrats