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Prince Rupert's drop (wikipedia.org)
117 points by limbicsystem on May 30, 2023 | hide | past | favorite | 35 comments



Shout out to Destin from SmarterEveryDay for his love of PRDs.

Learn about and see how it’s made – https://youtu.be/xe-f4gokRBs

Encasing a shattering drop in glass –https://youtu.be/C1KT8PS6Zs4

The process the team uses in the second video to freeze the break in glass is pretty awesome! (If you’re into that kind of thing)


Last time this was discussed on HN, someone raised the artist's approach to failure as a rich space for discovery, which was nicely put by him at this point in the video: https://www.youtube.com/watch?v=C1KT8PS6Zs4&t=1619s


Yeah, I love it. Learn about the entire process and keep going rather than cutting short after a perceived failure.


I think it is contextual, but it's a useful approach in many cases: it's effectively a sunk cost vs value of information analysis: if you've already sunk most of the cost into something and there's a problem which means it isn't going to work, then the potentially valuable information from learning about the next steps is probably pretty cheap, and reduces the risk that the investment in the next attempt isn't wasted. On the other hand, if you know it's not going to work and the next steps involve a lot of extra time/material investment but aren't going to tell you much, then it's probably a good idea to throw the current attempt away and try again.


There's also this one. https://www.youtube.com/watch?v=F3FkAUbetWU

He shoots the Prince Rupert's drop with a bullet. The bullet wins. In high speed, you can see the bullet splat against the glass and break into shards, long before the glass breaks. Really neat.


Related:

Prince Rupert's Drop vs Molten Glass [video] - https://news.ycombinator.com/item?id=35591019 - April 2023 (60 comments)

Prince Rupert’s Drop - https://news.ycombinator.com/item?id=31781678 - June 2022 (1 comment)

Mystery of Prince Rupert's Drop at 130,000 fps - https://news.ycombinator.com/item?id=5606228 - April 2013 (2 comments)

Prince Rupert's Drop - https://news.ycombinator.com/item?id=5550646 - April 2013 (13 comments)

The Curious Properties of a Molten Glass Blob Dropped in Cold Water - https://news.ycombinator.com/item?id=5440179 - March 2013 (5 comments)

Prince Rupert's Drop - https://news.ycombinator.com/item?id=486103 - Feb 2009 (2 comments)


Unfortunately the link on the third post now seems to go to an SEO spam site, but the Web Archive seems to have the original - https://web.archive.org/web/20170303072943/http://richannel.... which was a blog post featuring this YouTube video - https://m.youtube.com/watch?v=xe-f4gokRBs


Thanks! I added that info to the top of that thread.


The name alone, but even the description sounds like a special item in an RPG.

> 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.


It's funny because you don't need the drop shape to demonstrate this at all. Any random piece of tempered glass demonstrates the same thing if you know where the stress is.

You can hit a shovel against the flat side of a piece of tempered glass and not break it because the shovel is too large & flat. But you chip the corner, or use a small tool like a punch break, and the whole thing will pop.

Now, use the edge of the shovel against the edge of the glass and you'll have a lot more luck breaking it.


A Prince Rupert's drop can withstand a bullet - how would you demonstrate this with a random piece of tempered glass?


I mean, I only said it could withstand a shovel's flat side and a good whack. I never tried shooting any glass, but I have personally had reason to whack a few tempered lites with a shovel when they wouldn't break and can personally attest to how surprisingly hard it can be compared to just chipping a corner against another piece of glass.

Another odd thing is that when two pieces chip at the corners, I've only ever seen one of them break. Somehow the other piece always seems to survive, though it normally gets scratched up enough that it's tossed out anyhow.


So then it doesn't really demonstrate what a Prince Rupert's drop can do...


Not to the same extent, no, but you can still see it hit hard in one way and shatter under the slightest tap in another way which was all I was trying to say.



I mean, any means of applying force to a small area will make tempered glass explode. You just want to hit it with enough force on a small area.

The use punch breaks, which are like tiny ice picks with a flat handle, in the factory to do break tests to ensure that the glass is properly tempered. That will break it even when pressed down on the flat side of the glass.


Tempered glass will explode if you chip the corner??? I'm going to need to see a video or something to believe that


Yes, that's why they always protect the corners with a metal frame or put them in a window, etc. Though doing edgework beforehand may help avoid that somewhat.

Two pieces on the conveyor out of the quench running into each other is probably the most common way to break them in the factory other than having them explode in the quench. They also break in people's hands when you chip the corner on the racks they're loaded into, which usually makes the unloaders jump when it happens, because they may be holding a 30"x70" piece of glass that gives them a shower.

Oh, and the damn stuff can just break spontaneously. It might be due to temperature changes in those cases, it's not like anyone can say, but every so often a lite sitting in a rack will just blow up even when nobody is near it, though it's quite rare. From what I recall, it most often happens in winter.

Source: I worked for an cut & temper/IG operation for quite a few years and saw everything myself.


Tempered glass certainly explodes with minimal damage done to it. I've had plenty of panes blow on me at the solar panel manufacturing facility I used to work in.


Exploding glass shower screens are a thing. Usually due to damage to edge during installation (or manufacturing defect) and/or change in temperature.


In the factory, they sometimes seem to just explode randomly when the pieces next to them are just fine. It might be some anomaly of how they got quenched and/or temperature changes, though. I remember it mostly happening in winter for whatever reason, so maybe a cold breeze got them? There's probably quite a contrast between the furnace and the cold air coming in around the loading docks.


Here's a video with a guy tapping the corner with a hammer:

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

It doesn't need to be like that, just clipping the corner when racking it or having two pieces tap edges while it's on a conveyor will do it too.


Apparently if you use liquid soap instead of water you can get a drop with virtually no tail. Then the only way to really break it is by hitting it with a Nokia phone.


This is beautiful on his site - https://www.calbreed.com/prince-ruperts-drop/ The Beauty in Tension

…that glass bubble

That finds philosphers such trouble

Whose least part crackd, the whole does fly

And wits are crack’d, to find out why.

                           Hudibras by Samuel Butler, 1663 (on the mystery of the Prince Rupert’s Drop)


Crazy seeing this here. Someone posted this on the subreddit for The Three Body Problem books.


What was the relation? The strong force matter drops?


Just the shape is same as the droplet. Strong forces would be enough to kick that much Ass and not need to be like Rupert’s drop


There is definitely limited overlap between Reddit and here....

/s


This exact same article has appeared on HN repeatedly for at least 14 years:

https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...


It's funny, I've just discovered this drop two days ago, because it's mentioned at the end of Book 5 of Dungeon Crawler Carl (https://www.goodreads.com/series/309211-dungeon-crawler-carl)

A coworker shared this video about the artisan who makes theses drops https://www.youtube.com/watch?v=C1KT8PS6Zs4&pp=ygURc21hcnRlc...


articles on rotation like this could go on some faq-like list somewhere instead of frontpage maybe the list could be a tab at the top


The Finnish Hydraulic Press guy had a Reel recently showing how it just would not crush.


That's actually what prompted the submission. I was amazed :)


Prince Rupert Awakes: https://youtu.be/zHIapFdzRM8


Videos of people breaking these make my TEETH HURT. No I have not been taking my meds, why do you ask?




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