What Are These Marks Caused From? US Scott273

I was listening to a podcast the other day and they were talking about gum gutters I believe the term was.... Anyhow, I then remembered seeing these perf marks on the back of this Sc273. Is this what they may have been referring to - if I have the term correct? What are these marks from?? There also seems to be some other type of indentation in the upper left corner. Apologies in advance for the poor image - it's the only way I could get the marks to show - scanning wouldn't do it.

Not gum gutters. Did you mean gum breakers?

It looks like perforation hole patterns from a sheet laid on top or below for an extended period of time.

I agree with Partime.

partime is correct
they are common for this time period

Ahhh, that's it. Yes. Knew it was something like that. Tks. Had never heard of the term before.

Impression from other sheet it is then. The little square indentation had me going ! I'd never seen this before. I wonder why none of the ink was transferred? Just think if there was enough weight to make an impression, maybe some of the ink from the next sheet may have been left behind when separated. Kind of odd that I can't see any marks on the front of the stamp.

Those are always good to see, since they only occur on original gum stamps.

Stamps4Life, I think you have the same magnifier I use-- Carson?
Love both of mine-- one on my desk, and one in my backpack.

Actually, you apologized for your pic, but you did a really nice job of it!
Ray

Thanks ray. Yep on the magnifier…. I have 2 , the one you see and a back up in the drawer. Skeptical at 1st , thought cheapo, but it works well and I use it all the time. As a matter of fact, I have more of a problem with poor batteries & not the magnifier.

Thanks everyone for the replies and feedback. Learned something new again!

Wm.

wait, there's more! you mention lack of ink set-off. How do you know that was the 'face' of the other block of stamps??

(collectors, perhaps youthful, could stack a few too many stamps together inside a glassine envelope at any time...) When I foolishly stashed pile of plateblocks into glassines that I had too few of decades ago, I would at least alternate their facing, so "ink-side to ink-side" and 'gum side to gum side', to reduce likelihood of gum sticking onto front of next stamp. Capeesh? (or "Kapish"?)

Setoff is not gum sticking to dried ink and then pulling some off when separated, it is gum that came into contact with ink that had not fully dried.

No. The ink set-off of these early flat plate printings is on the paper, under the gum, which was applied later.
In contrast to poorly stored stamps which stuck together after sale and the ink is on top of the gum.

sorry, you are right about setoff for these being under the gum
my point was wet ink versus gum pulling off dry ink

These were common on the Pan American set. There was a thread around about them but I couldn't find it.