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Thread: Prince Rupertís Drops

  1. #1
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    Default Prince Rupertís Drops

    Pretty cool.

    from wiki:

    Prince Rupert's drops (also known as Dutch or Batavian tears)[1][2]are toughened glass beads created by dripping molten glass into cold water, which causes it to solidify into a tadpole-shaped droplet with a long, thin tail. These droplets are characterized internally by very high residual stresses, which give rise to counter-intuitive properties, such as the ability to withstand a blow from a hammer or a bullet on the bulbous end without breaking, while exhibiting explosive disintegration if the tail end is even slightly damaged. In nature, similar structures are produced under certain conditions in volcanic lava, and are known as Pele's tears.

    https://www.youtube.com/watch?v=xe-f4gokRBs


  2. #2
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    Default Re: Prince Rupertís Drops

    that's my buddy's youtube channel. he has lots of cool stuff on there if you like science.

  3. #3
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    Default Re: Prince Rupertís Drops

    he has a newer video of the price rupert drops blowing up in epoxy trying to catch it just right.

  4. #4
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    Default Re: Prince Rupertís Drops

    Found it. He’s a good science guy but sure could use some help with his epoxy technique. Near the end he gets a face full.

    https://www.youtube.com/watch?v=X3o71W4uNHc


  5. #5
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    Default Re: Prince Rupertís Drops

    Wait. Admittedly haven’t watched the whole thing yet, but right off the get go he says he’s going to recreate an experiment by Robert Hooke who made one of these in epoxy. Robert Hooke died in 1706. But he was experimenting with epoxy? I’ll watch the rest because I must be missing something.

  6. #6
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    Default Re: Prince Rupertís Drops

    I mentioned on another thread my glassblowing friend Susan. One thing that I did learn from Susan was that blown glass pieces go into a hot annealing oven overnight or so (I don't remember just how long or at what temperature) to give the glass a chance to dissipate the internal stress forces. That would likely also work for those drops.

  7. #7
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    Default Re: Prince Rupertís Drops

    So how is the physics of this any different than how Gorilla Glass - the stuff of screen protectors - or the decades old Pyrex cookware?

    As for annealing Tears, wouldn’t that negate much of their ‘indestructible’ globe ends’ toughness? Or is there some balance to be struck (no pun intended?).

  8. #8
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    Default Re: Prince Rupertís Drops

    Quote Originally Posted by sp_clark View Post
    So how is the physics of this any different than how Gorilla Glass - the stuff of screen protectors - or the decades old Pyrex cookware?

    As for annealing Tears, wouldn’t that negate much of their ‘indestructible’ globe ends’ toughness? Or is there some balance to be struck (no pun intended?).
    I think that the difference lies in the amount of internal stresses, and the way that breaking the tail triggers an almost explosive release of stress that reduces the entire teardrop to dust.
    You can make the teardrops from bog-standard glass, Pyrex has borosilicate added to the melt. Intended to resist thermal shock.
    It really is quite difficult to build an ugly wooden boat.

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  9. #9
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    Default Re: Prince Rupertís Drops

    Wow. Exploding sperm, with crystalline shrapnel that could put your eye out.
    If I use the word "God," I sure don't mean an old man in the sky who just loves the occasional goat sacrifice. - Anne Lamott

  10. #10
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    Default Re: Prince Rupertís Drops

    Don't want to brag Tom, but

  11. #11
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    Default Re: Prince Rupertís Drops

    Pyrex is actually formulated to minimize the thermal expansion coefficient. Pure silica glass has an even smaller thermal expansion coefficient than pyrex. You can take a piece of silica glass, heat it to 1,600C and put it into liquid nitrogen and it will not break, nor will it be significantly stressed, because the volume change during cooling is very, very small.

  12. #12
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    Default Re: Prince Rupertís Drops

    My mother bought an expensive pyrex casserole dish when I was kid. Used it once. Called us to the table, took the dish out of the oven and the bottom fell off it. We ate something else for dinner. JayInOz

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