Question Regarding The Effects Of Stamp Affixing Machines On Stamps

My guess is that the stamps were folded over before separation (often done to ease separating) and what you are seeing is a "fold over crease".
Don

Thank you! That makes sense... again, one of those marks that you see from time to time but not intuitive what it is

I'm posting a follow-up question to this thread because the content related to the appearance to stamp separations and perforations. Here I have a few more that exhibit appearances that don't look (to me) like ordinary separations. Can anyone tell how these might have been detatched?

Here the tooth tips don't have fibers, and from a distance the vertical axis looks mostly straight. The teeth are not all the same height but they don't look detatched from tearing -?



Here the focus is on he vertical side but also from the visible portion of the horizontal axis the teeth appear cut/sliced albeit not to the same heights:



In an earlier post I was told these kinds of teeth tips are the result of folding along the axis, and indeed that's what this looks like (teeth folded inwards) - but why aren't there any fibers at the tips? Was the stamp cut/sliced?



Unfortunately for the images to be sufficiently small to be accepted for posting the image here isn't 100% clear: the tooth tips show a decline near the tips down to their edge, like something mashed the paper at the tips. Any ideas what that might be?



The top horizontal perforation teeth are unusually tall and from a distance they look cropped, but looked at more closely the tips are not all straight, a few have some fibers and a couple have tips that lean to the left... what is this? Along the other perimeters the teeth heights all vary and bear no consistency.

Opinion.
There are fibres at the tips, you just cannot see them under this magnification.
Consider paper, modern harder calendered stamp paper, show reduced evidence of fibres.
Softer paper, 20th century issues do, some markedly.

Some used stamps, when they have been stored badly, in shoe boxes or plastic containers, can show rounded perf tips that basically are just damaged.

To me the perf tips in this thread look pretty normal.