Cup mark confusion

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"Cup marks" are the elliptical creases seen on Journey series notes where the security threads (i.e. the thin metallic-looking strips running down the left side of the note on the back) meet the edge of the note.  It is believed that cutting of Journey series sheets into bricks causes the cup marks.  This is what I have been told.

I have three consecutively-numbered $50 AHD notes in front of me.  I am not keeping them as they have cup marks along the bottom edge.  There are no cup marks on the top edge.  Notes with no cup marks along the top or bottom edges are inherently more desirable.  Why wouldn't notes that have cup marks have them at both the top and bottom?  I've never seen notes with matching sets of cup marks  

Can someone with knowledge of how these notes are made explain why this happens?

Guess I'm just clued out. Do you have a scan of what you're talking about?

here is a scan that shows it.

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and the other side

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If I recall Sudzee's explanation the security thread is tougher to cut than paper, and as the knife is bearing down with great pressure on a stack of notes the paper bends in this arcuate shape before the thread gives way to the knife.  Why do some not have them?  Perhaps the knife was sharper.  :-?

Here is a better pic of the cutting cup from a BABN ten.

The cutting cups appear on the bottom of BABN notes and the top of CBN notes.

These marks show up on approx. 75% of notes of all denominations that have the security thread. I have never noticed a note which has a cup at top and bottom. If you look at a bundle of BABN tens, cut from 100 sheets at a time, a cutting cup of varying size can be seen on notes 99 thru to about 25 but sometimes as low as 15. I believe the lower notes distort less since they are closer to the cutting table.

  

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One side of the blade is flat while the other is bevelled. Not sure which side creates the problem.  

Gary

Very Interesting....  

You learn something every day!  8-)

So I assume we can anticipate this problem with the new $5 notes?

Wouldn't it make sense that for every cutting cup that is on the top of the note, there is a corresponding cutting cup on the bottom of another note (situated directly above it in the sheet layout)?

I am not certian on when these cutting cups make it onto the note.  Is it actually from Cutting, OR is it from handling and picking upbricks by amachine perhaps (making them not really "cutting" cups)

Anyway, I have seen lots of CC's on the bottom.  But  like I said, I need to more about how they get there to begin with...


Now, to address rachels original question:
If you had to hold a square piece of lumber down with clamps to rip it into two even pieces in rectangle shapes, your resulting rectangles would only have the clamp marks on the one side of each, since the middle, (which was just cut) needs no clamps-because you are cutting it through there.  
This is what seems logical to me.
Huds

On the note of cutting, does anyone here who has seen a brick notice that when on its side, it looks like it was cut with a circular cutting tool? Not just a side to side blade?
Huds

I already noticed the pattern of cutting and it's caused by a blade cutting through the entire stack.  Sometimes, the blade has a small dent, so it leaves a mark on the side of a brick.  The mark is always oriented sideways.  The blade never cuts vertically through a stack of paper.  It has a sideways motion to ease the cutting action (otherwise, it would take too much pressure to cut and it would cause some damage to the paper).  And a pressure plate holds the remainder of the stack to avoid any displacement.

 8-)

Sweet!

These "cup marks" are by no means unique to Canadian notes. I have been seeing them for 5 to 10 years on many if not most world notes that have a security thread.  I have in front of me several crisp Unc Malaysian notes (over 5 years old) printed by Thomas de la Rue (the UK Printer) and they all display that annoying cup mark.

I speculate that the cup marks are caused because the security threads in the sheets would tend to elongate a bit during the first few milliseconds after the cutting guillotine first hits a brick of sheets. This expansion is due to the incredibly high pressure which would be transmitted almost instantaneously like a shock wave to the bottom of the brick. After the cutting process the security thread would tend to retract a bit and drag the edge of the paper with it thereby causing a crimp or "cup mark" at the edge. This may be an oversimplification but I'm pretty sure that the cup marks are related to this mechanical phenomenon.

It seems to me that the notes at the top of the brick would show less crimping/cupping than the notes at the bottom (although it could be the other way round!.) In fact, the very top sheet might not show any cupping at all(?)

NOTE: We now live in a World of Certified Grading (MS-60/MS-70) and we are going to have to accept that reality whether we like it or whether we hate it. It therefore makes sense to me that 100% Unc notes that display absolutely NO crimping/cupping are going to be worth more (and perhaps a lot more) than notes that do display crimping/cupping.

Maybe these indents are caused by the printing process, when the front or back of the note is printed, the wet ink, shrinks the paper, and shrinks at a different rate where the plastic/nylon thread is inside the paper compared to the rest of the note. After the ink dries, the paper is slightly wrinkled near the thread. Notice how the thread always protrudes outward, i.e. pushes up through the paper, so if you hold the note at an angle, you can clearly see the defining edges where the thread is. These crimps could be on the sheets even before they are cut. The only way to know is the see some uncut sheets.