What makes ribbon curl when you do that?

Factual Questions
1

You know, the ribbon at parties that you hang up all over the place. When you take the scissors and run the ribbon across the blade, and mysteriously curls. That a question I thought up in English today.

2

I believe one surface of the ribbon gets stretched more than the other, needs room to expand and therefore forces the ribbon to curl.

Cheers,
Oliver

3

You’re breaking the fibers (albeit very slightly), just as you do when you fold a crease into something like a piece of paper. In the case of the ribbon, you’re folding one long, continuous crease into the material, slightly breaking fibers all along the way.

WAG quotient of this answer: 54%

Hope this helps.

4

i’ve been wondering also. my guess is that kneadtoknow is closer to truth than waldenfont.

my reason is that the curl is towards the side touched by the scissors. stretching would make is curl away. similarly, breaking the fibers collapses that scissors side, making it curl in that direction.

WAG quotient of this answer: 55%. anyone out there have any facts?

5

Dig me setting trends! :smiley:

6

No facts, but I just did a little experiment. I tore a 1" thick strip of paper (sorry, no ribbon available), and managed to curl it in both directions 6 times (i.e. 12 times total). It seems to me that if you were breaking fiber, you wouldn’t be able to do this more than a couple of times, or at least the curls would be less, well, curly. That does not appear to be the case - the paper curled as readily the 12th time as it did the first.

7

The ribbon that curls best is the kind that has a series of folds along its length, perpendicular to the ribbon. A length-wise cross-section would show a soft zigzag: ///\ etc.

When you run a scissors blade (or whatever) along the ribbon, you tend to flatten out the zigs more than the zags (or vice versa, depending on whether you’re left handed or have a lazy eye). Thus you get a ZIG [sub]zag[/sub] ZIG [sub]zag[/sub] ZIG [sub]zag[/sub], rather than even zigzags of the unaltered ribbon.

WAG quotient: 0%

8

[Steve Martin]
Slightly is the key word here.
[/Steve Martin]

While I’m not about to go to any lengths to defend a theory I stated up front was 54% WAG, Running with Scissors, I don’t know that 12 repeats would really be enough to disprove the notion. After all, you can crease a piece of paper back and forth 12 times before it simply falls apart in your hands, and in doing that you are doing much more severe damage to the fibers than I suggested curling ribbon would cause.

Still, it’s grand to see that empirical science is still alive and well. Nice work! :smiley: