What Is "New Knife" Vs "Old Knife" For N Envelope (U567)

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I started collecting stamps in Elementary school with my Father; he died this year and I inherited his collection.

My Father knew about things I never heard of but with some digging I usually can figure it out; for example, different printing methods. I am a bit baffled with this one, however.

I am looking through his envelopes and on a 10 cent liberty envelope, he has two packs, one he labeled "New Knife" and one he labeled "Old Knife".



I do not see any specific differences when I look at the back of the envelope, but I decided that before spending significant time staring at the envelope I would just ask. They look the same to me based on a quick peek so I am not really sure how I would see the difference.

I also did not see anything in the Scott catalog that contains envelopes but is more geared towards stamps (which has been my focus). I expected that if there were variations that I would see other Scott numbers; like a U567C or something. Then again, I see envelopes with obvious differences such as with and without an address window but still only one Scott number (confused face).

Note that in the picture, I wrote U567, my Father labeled these as New Knife and Old Knife.

Ohio Andy, look at the back of the envelope and especially the flap. Can you see a difference ?


Peter

The Scott listings are hugely simplified. If you really want to collect postal stationery, then you need to get the United Postal Staionery Society cataogs, which provide the differentiation. In the case of Scott U567, they list 23 varieties in the "Catalog of the 2th Century Stamped Envelopes and Wrappers of the United States", based on knife, watermark, etc (1990 edition, which I had most closely at hand)

The backs look MOSTLY the same, but I see a difference right here with an envelope my Father labeled as "Old Knife":



Notice that the pointy tip is on the right and the right section is a bit higher than the left. The "New Knife" version is the mirror opposite with the pointy tip on the left and the left side is a bit higher than the right.

For actual catalogs, from here:

https://www.upss.org/code/publications.php

I see one labeled as:

"U.S. 20th and 21st Century Stamped Envelopes and Wrappers (2017) Editor Dan Undersander"

On the other hand, space is at a real premium and I just got rid of a bunch of things that I really liked just because I do not have space for them.... So, I would strongly prefer to NOT have a printed catalog, which brings me to this page:

https://www.upss.org/code/epublications.php

I am guessing that this one might list the item of interest:

"United States 20th and 21st Century Envelope Catalog as a PDF (Ver 4.3 2020)"

The advantage is that it will not take shelf space, but then I cannot sit on my couch and sort through envelopes, which would be nice (I know, buy a laptop).

Thoughts?