Mint Blocks With Perfins?

Hello,

I was curious if anyone knew why these blocks have perfins but are unused? Is this something that is more desirable since they aren't used?

To perfin collectors, used versus not used is immaterial. They are uncancelled for any number of reasons... most probably, based on the state of the gum, they were on parcels and somehow avoided the canceller; other cause - they were pilfered from American Radiator back in the day and the perp was afraid to use them.

Chasa: You referenced "American Radiator" as the identified owner of the "AR" perfin, but based on the example below, it seems they did not use serifs at the top of the letters "A" and "R" and the shape of the letters is different (most notably two lower perfins after the center perfin in the "A" rather than one). Are these other varieties of the same perfin or could they be attributed to another user?

Those extra holes are not serfis, they are 'control holes' - used to identify what city/branch they were used - AR had a big operation in many cities.