Half a croissant, on a plate, with a sign in front of it saying '50c'
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Shedding material

Loses 1 atom thickness of material every so often
(+3, -3)
  [vote for,

The material would have to react to something in the air (oxygen, water, pollutants, etc) such that it'd cause the material to slowly shed an imperceptibly thin layer constantly into harmless dust or gas. (No, I don't know how)


Dishes that clean themselves if left on the counter long enough.

Cars that keep themselves clean (and could gradually change color over their lifetime)

Paintings that look different every day.

Always-clean bathtubs, showers and toilets.

Graffiti-defeating wall coating.


seal, Jan 07 2002

Teflon is noncorrosive & therefore the opposite of shedding material http://www.teflon.c...ndustrial_home.html

How Teflon works http://www.cp-hotli...au/html/teflon.html [seal, Jan 08 2002, last modified Oct 21 2004]

How Teflon works http://www.cp-hotli...au/html/teflon.html
[angel, Jan 08 2002, last modified Oct 04 2004]

...and how it sticks to the pan. http://discovery.co...970606/skinny1.html
[angel, Jan 08 2002, last modified Oct 21 2004]

Self-cleaning glass http://www.ppg.com/gls_sunclean/
[reensure, Jan 10 2002]

Edible shed Edible_20Shed
[stilgar, Dec 28 2005]


       I was thinking along the same lines recently - was thinking about a carpet that grows a new "skin" under the old one, then you just peel the old one off for a "new" carpet. Flaking off would be a mess for some things.

I vaguely recall that there is/was a line of acrylic house paint, for the exterior, that was designed to shed small particles over its lifetime. It didn't crack or peel, but it would develop this very light dust on the surface. If you washed that off, then it would develop a new dust coat in a couple of months. Excellent color retention. I don't think this was a flaw, or that I had a bad batch. It was supposed to do this.
quarterbaker, Jan 07 2002

       our skin is doing this all the time, does it count.
po, Jan 07 2002

       Does oxidation count?
bristolz, Jan 07 2002

       (Imagines a thin layer of dust over everything)

       Hey! Your wall paint just shed on the dish on the counter which was shedding lunch... Where were we again?
phoenix, Jan 07 2002

       [peter] that's not how teflon works. In fact, teflon is extremely resistant to any type of corrosion & chemical reaction and is therefore the opposite of shedding material.   

       The molecular structure of PTFE is based on a chain of carbon atoms, the same as all polymers. Unlike some other fluoropolymers, in PTFE this chain is completely surrounded by fluorine atoms. The bond between carbon and fluorine is very strong, and the fluorine atoms shield the vulnerable carbon chain. This unusual structure gives PTFE its unique properties. In addition to its extreme slipperiness, it is inert to almost every known chemical.
seal, Jan 08 2002

       I don't understand how this would help with dishes and cars. They might lose a thin layer of material, but it would be their own material, not whatever would otherwise need to be cleaned off them. You'd finish up with an extremely thin plate with a thick coating of dried-on spaghetti sauce (or whatever).
angel, Jan 08 2002

       angel - no, because when it sheds, it sheds off whatever is on it. Like a snake (though that's one piece). Imagine the surface of the plate as being covered with all these microscopic doilies, and when they get peeled off, they take whatever is on top of them with.
quarterbaker, Jan 08 2002

       Graphite has a structure consisting of planes with a very weak bond between the planes, hence it slips apart easily and can be used for pencil leads and lubrication.
pottedstu, Jan 08 2002

       [peter] Try letting jam or ketchup or whatever dry on a solid graphite plate. After it dries, invert the plate and see how long it takes before the dried jam sheds off. (It won't)   

       Therefore, it's not baked. Even if it was a shedding material, pencil lead would mark everything up. However, you could argue that's how skin works. I'd just like to see the same properties incorporated into a solid material.   

       **Iron or steel flakes off as it corrodes (rusts), but the flakes are way too thick, big, ugly, messy, and it takes too long.***
seal, Jan 08 2002

       [angel] Doing a really rough calculation, if the atoms of this material were about the same size as carbon atoms, a plate one inch thick, losing an atom's thickness from both sides of the plate every hour would take 14400 years to dissolve into nothingness.   

       (Of course, this material's atoms might be 3, 4, 10 times as thick as the atoms of carbon.)
seal, Jan 08 2002

       This sounds very familiar ... it's a bit like the "exploding countertop" idea, in which countertops would be made of alternating layers of explosive and inert material, and to clean, you'd just detonate the topmost explosive layer, blowing all the crud off and leaving a nice fresh surface. Could presumably be extended to plates, shower stalls, etc.   

       I can't find the old idea. Maybe it was deleted. (Was it waugsqueke's?)
wiml, Jan 09 2002

waugsqueke, Jan 10 2002

       You could electro-plate your plate with something with a very short half-life. After a few half-lives, the top layer will have decayed to something else (ideally something non-lethal), and may even evaporate.
angel, Jan 10 2002

       Could you make sheds out of this material?
hippo, Jan 10 2002

       Oh no, the living room's shedding again. Would you go and clean it up?
st3f, Jan 10 2002

       st3f: Considering what an insignificant amount of matter is "shed" per hour, I doubt you'd be able to detect the shed material itself. (see time to dissolve 1 inch thick plate estimation above)   

       On the other hand, you would have dried dirt/grime/grafitti/foodstuffs dropping occasionally.
seal, Jan 10 2002

       Even if you could engineer the rate of decay of the surface material to an appropriate rate, you can't turn it on and off when necessary. Bits of your plate will be flaking off into your food as you eat.
waugsqueke, Jan 10 2002

       You say that like it's a bad thing.
angel, Jan 10 2002

       waugs, remember the premise of this shedding material is that *harmless* atoms or molecules would be shed.   

       Heck, eating a few atoms of darn near anything wouldn't hurt ya anyway.
seal, Jan 10 2002

       As has been pointed out, if you're talking in terms of a few molecules coming off during the time it takes to eat dinner, it will take months before enough surface material is released to clean the plate.   

       In order to flake off quickly enough to be viable, it's going to have to happen fast enough to get into my food in appreciable quantities. As well, dishes will rapidly get smaller until they snap in half.
waugsqueke, Jan 10 2002

       waugs, explain to me why the layer that sheds off *needs* to be thick.   

       (As long as it's uniform over the whole surface, that should do, right?)
seal, Jan 10 2002

       It's going to take more than couple of atoms flaking off to take food along with it.
waugsqueke, Jan 10 2002

       waugs: but -w h y-. Explain it to me like I'm 4 years old.   

       ...as long the entire surface has parted, who cares how thin it is?
seal, Jan 10 2002

       Seal - I think that waugs is thinking of scale (orders-of-magnitude scale) and its impact on what constitutes "surface." A smooth plate, viewed at sufficiently fine scale, will look like a very rough surface. The food stuffs will stick to both the high and low parts. The difference between the high and the low is almost guaranteed to be greater than one molecule (even the "smoothest" surface to human touch, of a material made from even really large molecules, will have a high/low difference of greater than 10 molecules). When you say "shed a layer," do you mean the outermost particles, or do you mean the particles at the object/air boundary? And really, that's what a surface is - it is a boundary region between dissimilar materials.

Perhaps it would do to use a couple of models here.

One model is a piece of wood, say a table. Say a bit of paint landed on the varnished surface. You want to sand it off. You'll have to sand away quite a bit of wood in order to get all of the paint off, since the paint goes to the lowest of low spots, and the sanding only takes of the high spots.

The other model is a snake. When it sheds skin, the entire boundary layer between snake and world comes off. The snake doesn't just rub off the outermost bits, even the deepest recesses between scales come off.

Seal is following the snake model. Waugs seems to be following the wood model.

So which model best fits?
quarterbaker, Jan 10 2002

       Thanks qb, for your insights. Since the molecules/atoms of this theoretical shedding material shed due to reaction with stuff all around it in the air, I tend to think of it as snake shedding skin (with the skin completely dissolving into microdust.   

       Of course, this would have to be strictly a non-porous material to work correctly.
seal, Jan 10 2002

       This blows. Even if a suitable substance existed it wouldn't work. The layer of stuff that was shed would remain where it was prior to shedding but without attachment to the plate (or whatever). It would still need to be washed off. A better name for this idea would be 'Self Dirtying Plates'.
stilgar, Dec 26 2005

       i refrained from reading this idea straight away, saved it as treat, because i genuinely thought it was going to be about sheds (how to stop then leaking or something), a subject close to my heart. forget sometimes that the universe doesn't revolve around my shed.
rainbow, Dec 27 2005

       [Rainbow] post an idea about your shed. Even if it's just
"Build a shed. From Wood"
It'd be better than this one.
stilgar, Dec 27 2005

       a shedding shed? no...wait a minute...i'm hungry...something is coming to me...   

       blame [stilgar]
rainbow, Dec 27 2005

       Eh? (thoroughly perplexed)
stilgar, Dec 28 2005

       Ah. No longer perplexed. (link)
stilgar, Dec 28 2005


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