We’ve all (at least, all of us who are Americans) seen American flags that are a little too long in the tooth, and are getting tattered at the ends. And invariably, when this happens, the tears are always right along the boundary between a red stripe and a white stripe. Now, for the high-quality flags where each stripe is a different piece of cloth sewn together, this would make sense: It just means that the seams are coming undone. But you also see it on cheap one-piece flags that have the entire pattern printed on.
OK, I might try to explain that by saying that the dye weakens the fabric somehow, but if that were it, one would expect to see tears anywhere within a (dyed) red stripe, not always right at the edge.
Have you examined such a flag closely enough to determine the tears are actually along the edges of the stripes, or does it maybe just appear that way when you’re looking at one flapping around in the wind at a distance due to the light/dark contrast, etc?
As others have said, I’d first need to see evidence that it happens at all.
But IF it happens, my guess would be that regular folding and unfolding according to a particular ritual might put stress upon particular spots. And it would be the same place in all flags.
Do a google image search for tattered flag. If you ignore the artistic results, almost all of the real flags depicted have torn exactly along the stripes boundaries.
For a sewn flag, if the seams were not coming undone, it could be the reverse - that the seams are still strong but the fabric they attach to has weakened.
As the OP says, there are “high-quality flags where each stripe is a different piece of cloth sewn together”. Nobody is disputing that they exist, and can separate at the stripes when they fray.
The OP claims that there are “cheap one-piece flags that have the entire pattern printed on” and that these also separate at the stripes. Where is the evidence for that?
Show me in Google half a dozen examples. Restrict your examples to the “cheap one-piece flags that have the entire pattern printed on.” It should be easy since according to you “almost all” of the images show this.
Maybe it’s just something like confirmation bias - maybe it seems that all tattered flags separate at the stripes because all tattered flags are sewn. (Maybe printed flags mostly fade before tattering and are mostly removed from view by the time the fabric would disintegrate.)
you can see that the tears are simply down between the warps.. the strong thread.. Some of the tears are close to the stripe junction, some are down the middle of a stripe.
The material is weaker when torn one way (torn horizontally) compared to the other (torn vertically).
It lasts longer if the warp is horizontal. If the warp was vertical, it would tear off at the mast end much sooner.
I’ll see if I can find some actual examples to get pictures of. There were a couple I saw recently that reminded me of the question; maybe I can remember where they were.
From your video (at 56 sec), the one rip the spans the length is thru the middle of the white stripe.
My guess is that horizontal rips on a horizontal pattern that’s not very close to the viewer, & moving, create an optical illusion that it’s exactly on the stripe edge.
We just got a new flag, took a while to find one made in the USA. It’s stitched so I looked at the old one and to my surprise it was printed. But it’s not tattered, just faded. I don’t know how a flag gets printed, I suppose there a could be a multi-pass process that weakens the fabric between the stripes but seems unlikely as an inexpensive manufacturing method. Isilder’s explanation sounds pretty good though. Seems unlikely that the fabric would tear rght in the middle of a stripe making it apparent that the tears were randomly located so at a glance a flag would seem to be ripping between the stripes.
Can you calculate pi based on the random location of rips in stripes?
That, at least, I can answer. You’re thinking of Buffon’s needle. But that’s a different problem, because the probability of the needle crossing a line depends on the orientation of the needle, which is uniformly distributed among all possible angles. Given a uniform distribution of angles, it’s easy to come up with a circle, and hence pi. Here, though, the (presumed) uniform distribution is in position, not angle, so it doesn’t help.
Thank you. I didn’t expect you could calculate pi from a tattered flag but that is still an simple and concise explanation of why you can calculate pi by dropping needles across parallel lines. Not necessarily easy for anyone to follow that through, but using the random distribution of angles to related to a circle makes sense.
Not flags but painted signs on what was cheap canvas or even old bed-sheets - when they had been outside some time linear tearing would be close to the painted letter edge but always on the unpainted fabric.
My assumption was that the paint was enough to strengthen the fabric so, as one of the earlier posts suggested it created differential stress when flapping about. Another consequence of painting or dying would be that those threads were less absorbent, and so would take up far less water in the rain and suffer wetting-drying stress or any of the other seven painted signs of ageing. The unpainted fabric became, pun intended, threadbare.
