Observations on the newly discovered miraculous Asian shirt-folding technique

[mmcirvin]

To add to my comments in pentomino's post on the subject:

There is an equally efficient technique based on the same principle that is less theatrical, and thinking about it reveals much about how the magic-looking method works.


Start with the shirt front side down with the collar end pointing to your right (this is the one part that is possibly less efficient, since it makes it harder to button the shirt if it has buttons). Then, you basically do the original steps 2 and 1 in reverse order. Bring your left hand across to the right, and grab the shoulder furthest from you at the position where you want the longitudinal fold that will define one edge of the folded shirt. Bring it across to the other end of your planned fold at the bottom of the shirt, and pinch it together with the shirt-bottom there.

Then, with your right hand, grab the corresponding point on that fold at what would be the middle of the shirt's length (the same point on the shirt that the original technique had you pinch in step 1).

Now you've defined both endpoints and the center of the first longitudinal fold by the spots where you're grabbing the shirt. Your right hand also defines one point on the central transverse fold, but you only need one point, because gravity and geometry will do the rest for you when you lift up the shirt with some tension between your two hands.

This version is elegant and simple, but not particularly astounding to the viewer. Now, the mind-boggling version is exactly the same in principle, except that you're also taking advantage of the non-rigidity of the shirt and grabbing the important tension points when it's in a configuration whose transverse fold is inside-out from the final one. But since your hands are grabbing the shirt in exactly the same spots as in my demystified technique, the fold will come out the same as well.

I apologize for removing the mystery and wonder from the world. Be sure not to tell your marks at the laundromat what's going on.

Update: As I said in the comments, the technique as described above actually puts the initial folds in mirror-reversed positions from the other version, because the shirt starts out face down. Also, further experiment reveals that while the folds end up in the same places with the two techniques, the stacking order of the folded cloth comes out different. The fancy technique ends up logically equivalent to doing the first longitudinal fold first, then the transverse, then the second longitudinal as you lay down the shirt, which is kind of unusual, whereas mine gives the transverse fold priority.

Comments

[mmcirvin.livejournal.com]

...Actually, I suppose that, in my technique as I described it, you aren't grabbing the shirt at the same points but at their mirror images. To get it exactly the same, you'd have to start with the longitudinal fold on the side nearest you. Still, the principle is identical.

[mmcirvin.livejournal.com]

Man, I wish Martin Gardner were still writing "Mathematical Games" for Scientific American. This would be prime material.