WARNING....That green stamp is fragile and will disappear with even a little bleach and or heavy scrubbing.
I soaked 2 over night that were almost black and 1 had the same stamp. The whitest strops I ever cleaned. Including where the print was.
Lost some on another scrubbing.
And Phrank you need to find some of this
Attachment 187383Attachment 187384
I have yet to try Richards hanging method but it is a proven success. I lay mine out on hot concrete and press them flat. Advantage of living in a desert. Some days it will dry in an hour or 2 :<0)