I was thinking about that movie Shanghai Noon(buying it, I like the movie), and when Jackie Chan and Owen Wilson were in the jail, Chan urinated on a shirt and said “wet shirt no break” and proceed to wrap it around the bars and twist/thereby squeezing the bars together. Owen Wilson replies, “you said wet shirt no break, not piss shirt bend bar”. Hilarity aside, also lets put aside the fact that doing that would not work.
I do know that wet fabric seemingly is stronger, does anyone have an explanation of why? The only answers I can find are from Yahoo! “Answers” and the people on there are clueless about everything.
On a similar note, why do towels get seemingly more wet as a they dry? is it the moisture distributing itself?
I just woke up An hour ago and still on my first cup, these are the pressing questions of the day!
I think the explanation to your first question is the same as for why it’s possible to build sand castles from wet sand: surface tension binds the individual fibers/grains together.
They’re obviously orders of magnitude less stable than solid rock, but also orders of magnitude more stable than a structure similar to this built from dry sand, which, if at all, could only exist in zero gravity.
I also note that both explanations linked by Omar Little are making the assumption that Chan’s shirt (it’s more like a robe, really, IIRC) is cotton. I would rather expect a Chinese palace guardsmans dress to be made from silk. (Not that it necessarily matters much: fibroin, as cellulose, contains a lot of hydrophilic groups.)
I have to use natural linen bow strings when competing in the primitive archery flight championships. We like to use the lightest string possible for more speed. Wetting our string or even higher humidity will greatly increase the strength. When testing samples guys will often complain about inconsistent results taken in different part of the country. It is because of the humidity.
Even so, surface tension isn’t going to contribute significantly to the tensile strength of cloth, because it’s a very feeble force - it’s enough to stick lightweight grains of sand weakly together, but you can separate them with a light finger touch.
Also, that image is photoshopped. I doubt such a structure could be built just using wet sand with no other binding agent.
It’s most likely polystyrene with sand glued to it to provide texture. Fun fact: Mount Vernon’s exterior walls are covered in wooden “bricks” which sand was glued to to make them appear to be stone.
Well, gravity is a feeble force, but given enough matter to work with, it can accomplish notable results. Same thing with surface tension: given enough surface (and I have no idea of the surface of all the internal films and strands of liquid in a twisted wet shirt, but my guess is that it could well be a significant portion of a square mile!) it could and would amount to something.
Mind you, I’m not suggesting that surface tension would do most of the pulling; merely that it could, at least in theory, make a difference by cross-linking individual fibers, thereby saving the fabric from tearing. But I know nothing; it’s just a guess.
Is it because when the liquid lubricates the fibres, it takes less force to pull the material to taut…
Your brain is used to guaging the strength of material by its stretchiness … but the stretchiness is reduced when wet… so it feels stronger… a poor, non-destructive, method of gauging strength…
Breaking strength isn’t altered, or its even reduced as the individual fibres are more easily pulled and broken one (or in lesser numbers ) at a time ?
Natural fibers not counting silk have very little stretch, the moisture can up to 30% strength. I think it has to do with pulling taught and equalizing more the strain between individual fibers, giving it the properties of something more homogenous.