These are the only known and certified blanks from the U.S. Mint for the 40% Silver Eisenhower Dollars that have an experimental rinse. These were discovered in a hoard of San Francisco Mint Errors. It has been almost 40 years since Ike Dollars were struck and no others have been found. These unique blanks each have specific notations by the Mint and are included on the NGC inserts. An experimental rinse was applied to the blanks to prevent spots and tarnish.
(3) Silver Ike $1 Planchets Experimental Rinse Blanks Have Notations By The Mint Discovery Group of 3 Blanks Certified by NGC From The San Francisco Hoard UNIQUE