Sciencemadness Discussion Board

Prince Rupert's primary?

Bert - 25-12-2017 at 09:16

Perhaps the fumes from the eggnog are affecting my reason, but I've had a thought.

I just watched a prince Rupert drop shatter. Speed of propagation quoted as speed of sound in the glass, around 1,600 m/second for cheap, low density soda glass. That's a good bit faster than is required for a bullet to initiate some secondary explosives, granted that this effect has some other components than mere speed of a projectile impact.

"Glass" can be a lot denser than this. Not sure about the thermal coefficient of expansion to produce the stress required for the effect in the very dense glasses, leaded glass? Optical (flint, crown?) glass? A quick look at online sources for predicting speed of sound in solids shows several other physical characteristics that will affect this, have not corelated these with any candidate materials yet. But let's assume it is possible to fabricate stressed "glass like" objects cranked up in density and otherwise tuned to "shoot" as rapidly as possible? Perhaps obtaining propagation speeds of shattering 2-3X or more of the observed speed in soda glass???

Initiation of secondary explosives is said to depend on the speed of the impulse applied more than the total energy of that impulse... Some relatively low energy but high speed reactions are known to serve.

Has anyone tried initiating a fairly sensitive secondary via the stress release from this type of shattering? A type of NPED detonator with no fuse, electric match or high speed discharge of hefty capacitors required. Just scratch the "tail" to shoot.

[Edited on 25-12-2017 by Bert]

aga - 25-12-2017 at 09:26

Interesting idea.

Not sure the finished item would be safe to transport.

Maybe best to pack with mince pies for safety.

NEMO-Chemistry - 25-12-2017 at 11:47

Wouldnt this also be safer? The tails can be protected. Yes its a really interesting idea, I am surprised the speed is the same as sound waves in the glass. In slow motion films it looks alot faster than that.

A drop made with quartz glass would be interesting to film shattering. Do they shatter along a defined stress line or is it more a wave moving forward effect (if that makes sense?).

SWIM - 25-12-2017 at 13:20

I believe the high lead content glasses aren't really glasses but crystal, so in addition to the added density there may be some effects from the (presumably) less flexible material.

Might give higher kinetic energy?

Σldritch - 25-12-2017 at 13:59

The energy from the explosion comes from strain in the surface of the glass. It should be possible to increase it by squeezing in ions in the glass. Applied science made gorilla glass by immersing microscope slides in molten alkali nitrate for some time.

I think this is better suited as a cheap primary because you will still want to be far away from any explosion involving glass and/or a secondary. If you used it as a detonator you would still want to trigger it electrically for maximum safety. The easiest way to do that - assuming the tail of the drop is somewhat resilient - is with a small detonator which would just add unnecessary complexity and danger of accidental detonation.

Still i think it will be hard to get to work reliably because of the tails varying shape and the droplets stability. Maybe you can see it with polarized light or something?


Writing on mobile sure is a pain...

[Edited on 25-12-2017 by Σldritch]

nitro-genes - 25-12-2017 at 14:30

Very interesting phenomena and idea :)

In terms of energy density, transfer and "pressure" produced it is unlikely to work as a primary probably, at least for normal soda glass. Glass is almost incompressible (like hydraulic fluid), so unlike a rubber band e.g, I would say it can only store a very small amount of energy.

[Edited on 25-12-2017 by nitro-genes]

Dornier 335A - 25-12-2017 at 15:05

Two properties are required here, the drop needs to store a good amount of energy and it has to have a high speed of sound. Since the outside layer is compressed and the inside is stretched, the material needs good tensile strength and toughness to store a lot of energy. Soda glass has an ultimate tensile strength of around 33 MPa while fused quartz has 48 MPa so there is quite a difference there.

Speed of sound is calculated as the square root of the bulk modulus divided by density, so to get high speed of sound the material needs to be light, not dense! The speed of sound in glass is between 4000 and 5000 m/s and a bit higher, 5800 m/s, in quartz according to some sources.

Bert - 25-12-2017 at 15:24

There are at least two technologies besides the liquid quench induced strain of the classic Princ Rupert's drops. One is placing melted glass in a chilled metal mould, such that the skin is frozen while the interior is still plastic and expanded.

The other I know of is to fabricate the (Soda) glass shape, and then soak it in a melt of Potassium nitrate. A good portion of the Sodium atoms in the outermost layer of glass will exchange with Potassium from the melt, as I see it described, potassium atoms require about 30% more volume than Sodium, which causes the Potassium doped skin to compress the Sodium based core material.

Both of these methods bypass the random tadpole shape of the classic Prince Rupert's drops and allow fabrication of the proposed initiator element to an optimized design via a reasonably repeatable process.

So, let's make a heavily stressed more or less rod shaped glass bead with a very narrow parabolic indentation in the far end from that which will be scratched, snapped or otherwise initiated. Load that parabolic cavity with very fine crystals of NON phlegmatized PETN, mannitol hexanitrate, etc. and point it into the next stage of the detonator.

Bert - 26-12-2017 at 11:16

OK, I am eggnog free and the idea of a (cheap) simple mechanical replacent for the initial primary explosives in a firing train still is interesting.

I can find references to silica based glass with relative density as low as 2. Not yet linked that to specific mixtures, but Lithium oxide is claimed to make a good flux.



Question: Glass is a silica based mixture with various fluxes and modifiers, never intended to do what I'm thinking of here. So what other melts of elements, chemical compounds or blends could be encouraged to behave similarly? Hard, light, tough but not TOO tough, large coefficient of thermal expansion, cheap.

Next question, is glass/whatever with thermally induced stress the ideal stored energy system, or just the first one to pique my interest... The forest just got a lot bigger.

Attachment: Glass-Fluxes.pdf (128kB)
This file has been downloaded 379 times


NEMO-Chemistry - 26-12-2017 at 11:21

Would looking at very high temperature glass be the best start point? The glass used in multi fuel stoves might be a good candidate. Not sure what glass it is though.

https://www.ceramtec.com/perlucor/

Lye resistant!!! Ok thats off topic

I sent an email asking if Prince Rupert drops would be possible with this material, no idea what kind of reply i am going to get :D
Lets hope someone with a sense of adventure gets the email....

You never know, they might go Hmmm lets see.

[Edited on 26-12-2017 by NEMO-Chemistry]

[Edited on 26-12-2017 by NEMO-Chemistry]

[Edited on 26-12-2017 by NEMO-Chemistry]

unionised - 26-12-2017 at 11:48

Fused quartz is well known for a low expansion coefficient.

NEMO-Chemistry - 26-12-2017 at 11:54

Quote: Originally posted by unionised  
Fused quartz is well known for a low expansion coefficient.

I will watch this thread with interest, but clearly its way over my head so I am bowing out of taking part.

Bert - 26-12-2017 at 12:14

Hey, I did those public speaking exercises they make us do in USA high schools, around 40 years ago. One "information speech" was on glass technology- So my personal store of info is just a BIT dated.

Think we're all about equally disadvantaged here, jump on in, the Googling's fine.

NEMO-Chemistry - 26-12-2017 at 12:39

You have probably seen this, but wiki says the property is also found in Volcanic particles, it also mentions the university of Bristol doing research on it. I did a little google and it looks like they have done research from the volcanic perspective, BUT reading the University site it also appears they have a lab devoted to the properties of glass. Unless i have misread something, so i might have a look and see what research they have done, if its relevant to volcanic particles then there should be alot of information.

Wiki also gives some figures for speed of propagation, these are phenomenal. I might do some digging and send some emails, cant hurt to ask can it.

Also some direct research this year on PRD is here https://www.purdue.edu/newsroom/releases/2017/Q2/research-so...

It has an interesting paper and video

paper http://sci-hub.tw/10.1063/1.4971339

Video https://youtu.be/lt-zvsGvtqg

Cambridge University might be a better choice for me to email. Any idea of what kind of thing would be useful to ask?

EDIT]
I missed a link. One of the researchers has made information available on his google drive thingy

https://drive.google.com/drive/folders/0B5pvN1C9I3pbWnlKaUNC...


From a safety aspect, this is an interesting video, watch the bit leading upto 2:40 mins https://www.youtube.com/watch?v=dViDJti9eCA

They use a hydraulic press to sink a drop into a solid lead block, the guy tries to then break the drop by breaking the tail. The drop dosnt break.. I am not sure if it dosnt break because he fucks up the tail break, or if its because of being sunk in the lead block.

But it might have implications if you are putting it into a explosive.
At around 4:12 they dent a steel block and the drop goes off, a tiny fragment hits the go pro casing and breaks it! The bit that hit must have been tiny

[Edited on 26-12-2017 by NEMO-Chemistry]

[Edited on 26-12-2017 by NEMO-Chemistry]

[Edited on 26-12-2017 by NEMO-Chemistry]

[Edited on 26-12-2017 by NEMO-Chemistry]

MineMan - 27-12-2017 at 16:06

I think Bert's idea will work. In the youtube video NEMO Chemistry shows us, the steel block is dented. Perhaps we can also use wave shaping, and put a hollow hemisphere in the strained glass (at the business end), and load this with a secondary too.

I think this is something worth looking into. I am placing my bet on the side that this is feasible, and in a small package too, like a standard detonator tube. We don't need a lot of energy, just a good impulse. A minuscule amount of plastic or foil sets off PETN very well in slapper detonators.

We could also use a high power but common 2W blue laser to set off the strained glass. Add a dark pigment to the glass so it will absorb light, and have a fiber optic cable touching the sensitive end of the glass...

[Edited on 28-12-2017 by MineMan]

nitro-genes - 27-12-2017 at 17:12

The most interesting feature of the hydraulic press movie Nemo posted is that when the drop is pressed into the lead block, only part of the tail explodes, but not nearly as far as all the way to where it contacts the lead. Maybe the drops werent made properly. Alternatively, I was thinking maybe resonance is playing a big role here, the tadpole tail acting like sort of a horn.

[Edited on 28-12-2017 by nitro-genes]

markx - 27-12-2017 at 19:34

Quote: Originally posted by nitro-genes  
The most interesting feature of the hydraulic press movie Nemo posted is that when the drop is pressed into the lead block, only part of the tail explodes, but not nearly as far as all the way to where it contacts the lead. Maybe the drops werent made properly. Alternatively, I was thinking maybe resonance is playing a big role here, the tadpole tail acting like sort of a horn.

[Edited on 28-12-2017 by nitro-genes]


A interesting concept indeed....for some reason I tend to think that perhaps the intimate contact with a soft malleable metal like lead disrupts the propagation of the destructive wave in the glass to an extent where it no longer is able to break the material apart. The strain is mostly concentrated in the outermost top layers of the glass drop so it would make sense to think that if part of the energy is absorbed by something in intimate contact with the top layer of the glass, it might bring forth a situation where the destructive propagation of the wave stops altogether.

Morgan - 27-12-2017 at 19:43

If you can put the drop in your hand and shatter it by breaking the tail, it will probably sting but is that going to be enough directed force as opposed to holding a hot primary or catching a speeding bullet in your hand? I'd like to see it work but something like tannerite seems like a Rupert drop among the prills just wouldn't get it.

"The King would have a subject hold the bulb end in the palm of the hand, and then break off the tip, giving the startled person a small explosion right there in a closed hand. It was harmless fun, though, as the glass shatters into powder, not into jagged shards."
https://www.cmog.org/article/prince-ruperts-drop-and-glass-s...

Perhaps a snapping shrimp? (It just came to mind as something fanciful albeit doubtful)
https://www.youtube.com/watch?v=ONQlTMUYCW4#t=1m5s

The snap of the bubble also produces something called sonoluminescence, i.e., emission of short bursts of light. When the cavitation bubble collapses it reaches temperatures of over 5000 Kelvin. That is almost as hot as the surface of the sun, estimated at around 5,800 Kelvin. This produces a flash of light which lasts for no longer than 10 nanoseconds and is not visible to the naked eye.
Watch the pistol shrimp’s snapping action in this fascinating BBC video.
https://learnodo-newtonic.com/pistol-shrimp-facts



[Edited on 28-12-2017 by Morgan]

Bert - 27-12-2017 at 20:03

How about firing a drop inside a calorimeter. There is some information on rate, need to get a handle on quantity.

After New Year's , I hope to have time to melt some glass.

Thanks to all for the ideas and links. I've already learned things.

NEMO-Chemistry - 28-12-2017 at 02:54

I got alot more to post, but first some info, you cant change the shape of the top of the bead. In the paper i linked to it explains why, there is a 2013-2014 paper that has been found to be wrong.

The one i linked to is apparently the paper that explains the mystery of how the drops work and the forces involved. I didnt understand alot of it, but it does mention the shape being intrinsic to the way it works.

But when you read other papers on glass, it becomes clear you could attached another shape to it. But the drop itself has to be the shape it is. Velocity and forces are in some the papers I have seen, i will dig those out.

To give you an idea of speed of propagation, one the reasons it took 400 years to fully understand the things, was the fact that they didnt have ultra fast cameras to look at it.

Large drops pack a punch, yes they shatter harmlessly in your hand, until you scale up to around 6-7cm. Apparently at that size you get some force in it. All of this is a mix of info from 15 papers I have read so far.

I am reading stuff to find the most relevant, i will post those in references i guess. NON soda test tube glass is scary!! I used map gas to melt a bead and tried it, use glasses with that stuff!

In the video as i mentioned above, a tiny bit of the glass hit the perspex progo camera cover and broke it. Watch it really carefully again, the glass fragment is tiny! Non soda glass is like soda on steroids and TBH i didnt want to do too many! When they shatter in a gloved hand you feel it, it kinda stings a fair bit.

I found quickly melted glass to work best, i think this is so you dont soften the glass to the point its normal glass. just guessing but maybe doing that leaves part of the glass already under stress, but again, seriously make sure you got decent face protection!

I will post other stuff once I finished my distillations!! I have heating issues!

Morgan - 28-12-2017 at 06:57

That would be interesting to see and hear a 7 cm Prince Rupert's Drop go off. It brings to mind those heavy "Pyrex" dishes that sometimes bomb shatter if heated and a few drops of water placed on them or performed by setting them on a wet surface. There's a lot of sound produced in ideal conditions. Once I microwaved a cereal bowl that wasn't microwave proof just for a short time thinking it would be OK, but when it shattered the sound it produced was stunning.

Those Bologna bottles that are stressed like the Rupert drop, could a secondary be triggered in those somehow?
https://www.youtube.com/watch?v=DAmNmWpxo8Q
https://www.youtube.com/watch?v=rdcss3Sx6xk

nitro-genes - 28-12-2017 at 08:26

Quote: Originally posted by markx  
Quote: Originally posted by nitro-genes  
The most interesting feature of the hydraulic press movie Nemo posted is that when the drop is pressed into the lead block, only part of the tail explodes, but not nearly as far as all the way to where it contacts the lead. Maybe the drops werent made properly. Alternatively, I was thinking maybe resonance is playing a big role here, the tadpole tail acting like sort of a horn.

[Edited on 28-12-2017 by nitro-genes]


A interesting concept indeed....for some reason I tend to think that perhaps the intimate contact with a soft malleable metal like lead disrupts the propagation of the destructive wave in the glass to an extent where it no longer is able to break the material apart. The strain is mostly concentrated in the outermost top layers of the glass drop so it would make sense to think that if part of the energy is absorbed by something in intimate contact with the top layer of the glass, it might bring forth a situation where the destructive propagation of the wave stops altogether.


Exactly what I was thinking first! Later in the video posted on youtube the guy snaps the tail of one of these drops which is only partly embedded in the lead. I was very surprised to see that no propagation seemed to happen at all, he almost cleanly broke off the tail. Wouldn't this be hard to explain taking only a moving front of fracture propagation into account? (given that the drops were properly made)

Bert - 28-12-2017 at 10:21

A 7 cm drop?! You mean just the length of the head? I assume the viscosity of the melt would determine what size drops can easily be made, so perhaps less flux?
.

I am seeing references to cold water being desirable to speed the quench in order to create more stress and wondering about the tradeoff between possibly slower cooling of the skin due to the lowered heat capacity/volume of a water/glycol mix and the lower temperatures possible from a sub 0 C. liquid for quenching. Something to try, it is well below 0 F. here right now.

Prince Rupert was an interesting character. May have invented one of the mezzotint processes, he originated the hand tool still used to punch the matrix of dots into the Copper printing plate for the dark to light process. Said to have come up with the idea by looking at dark oxide trapped in rust pits on a sentry's musket barrel while the soldier was trying to polish the rust dammage away- Pity his uncle was such an inadequate king, the English civil war certainly put a crimp in the prince's many intellectual and artistic endeavours.

Yes, learning things...

aga - 28-12-2017 at 10:40

I suppose the experiment would be to make a fairly sensitive secondary, melt some glass into a bucket of water and see what happens.

What would constitute a "fairly sensitive secondary" ?

Bert - 28-12-2017 at 12:05

Unphlegmatized fine PETN or mannitol hexanitrate come to mind. Possibly also very fine particles of RDX from air spraying fine droplets of RDX dissolved in acetone into rapidly stirred water, there are patents on tuning up sensitivity through smaller particle size.

A while back, I had to break a bunch of light bulbs on a theatre marque sign for a video project. I used commercial electric matches with 15mg of 80:20 Mercury fulminate : Potassium chlorate introduced into to the plastic safety shroud on each match and a scrap of tape to hold it in, these were super glued to glass envelope of each bulb just above the metal threaded base. Absolute minimum charge to reliably break the glass.

I had some of the "enhanced" electric matches left over after doing the job, and wondered if they would set off a commercial Tannerite target. Answer: yes, 3 out of 3 fired from that tiny charge. Not much power there, the tiny pinch of composition would only split the plastic shrouds open for about 1/4" at the end, the plastic bits didn't even detach.




aga - 28-12-2017 at 12:16

Mmmm.

I might have a go at making some of Prince Rupert's droppings.

Not sure i really want to stray into the Dark Side, i.e. the fizz-pop-bang world.

NEMO-Chemistry - 28-12-2017 at 14:57

Yes sorry Bert the size was 7cm from tip to start of the tail (will come back to that) the size of the head was around 1.6-1.8cm, I tried to measure it, and i know this is stupid but, i was really nervous! I am aware they dont/cant go off unless you break the tail, but having felt a slightly smaller one break, reason went out the window.

Soda glass seems to behave differently, the pyrex glass packs a much much bigger punch. The glass rod I used was 2cm in diameter, but obviously the bead distorts and gets smaller.

The tail....You can see where the tail starts, i havnt played much but if you look at the arse end carefully, you see a change in the light refraction, the bit where the colours just start to appear is the tail, they wont shatter unless you break them just past this point. Well so far thats my observation.

Aga i wouldnt want to start testing anything that goes bang, not until you get a good feel for these. Honestly the soda stuff is childs play, but use pyrex and its a whole other level. The water i used was around1-2c.

I have salt water in the freezer, this normally gets pretty close to -17C and still liquid (well bottom part is liquid). I think your going to find a point where the beads shatter on contact with the water if its 'too cold'. Nothing to back that up, but i did have a couple break at 1-2C as they hit the water, obviously that could be for any reason.

Try not to make the tails too long, try and melt the glass fast and cool fast. No data at all to back that, but the few i tried seemed more.....lively the quicker i melted them. Just an idea but with larger pyrex ones I wore welders gloves, it might be overkill i dont know yet!

I also swapped my goggles to a chainsaw toughened plastic type face shield, small bits do fly about at enormous speed, seeing the go pro case i wont take chances getting it in the eye.

Bert your the explosives expert, i will wait to try anything that goes bang until you have. I dont mind doing stuff on the beads and I am collecting papers etc, i can make the beads as I have gas etc....at the moment its the only heating i do have!!

Oh one last warning...........

DO NOT miss the bucket with a drop while you got slippers on!!! Lets leave it at that ok :D

Morgan - 28-12-2017 at 15:51

Here's kind of a loud drop.
https://www.youtube.com/watch?v=j7CeZuM_8OE
I wonder what the upper limit is for size on a Rupert drop?
https://imgur.com/gallery/PXzBm

NEMO-Chemistry - 28-12-2017 at 18:22

Quote: Originally posted by Morgan  
Here's kind of a loud drop.
https://www.youtube.com/watch?v=j7CeZuM_8OE
I wonder what the upper limit is for size on a Rupert drop?
https://imgur.com/gallery/PXzBm


The fourth picture shows very nicely what i was saying about the colour, if you look you can see the colours end abruptly at the tail. Its at that point the things go off if broken, they can break a little further up but they dont shatter.

So the 'safe' bit is anything coloured or just slightly below that point.
I tried to make sure the tails were fairly short, its really easy and frustrating to break them when the tails are long and thin.

See what I mean about a good face shield :D

EDIT
Added 3 files that might be useful


[Edited on 29-12-2017 by NEMO-Chemistry]

Attachment: johnson1992.pdf (1.6MB)
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Attachment: chaudhri2009.pdf (235kB)
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Attachment: chandrasekar1994.pdf (5.4MB)
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argyrium - 29-12-2017 at 10:15

It would be interesting to see what would happen if a drop was suspended in a mass of clear epoxy with only the tail sticking out. Once cured, snap the tail (at a distance).

aga - 29-12-2017 at 13:40

It would be interesting to see Anyone posting comments along with photos and data (if possible) of Their Experiments, rather than random google results.

Bert is kinda exempt as it is his idea after all.

If Geocachemaster is reading, i intend to do a utoob video on it.

[last time i let on i was going to do something he immediately did a video on it, so here's hoping he'll Do It again]

NEMO-Chemistry - 29-12-2017 at 16:36

Quote: Originally posted by aga  
It would be interesting to see Anyone posting comments along with photos and data (if possible) of Their Experiments, rather than random google results.

Bert is kinda exempt as it is his idea after all.

If Geocachemaster is reading, i intend to do a utoob video on it.

[last time i let on i was going to do something he immediately did a video on it, so here's hoping he'll Do It again]


Erm thats exactly what i have done!

No one sane is going to go set an explosive off without alot of work first. The drops bit i did above and posted my obs, then i went (along with others) and found stuff to back it up.

Yes its Berts idea, but saying he is exempt is contrary to your normal rants. Normally you tell people not to ask questions but go try it, so how come with Bert its ok to sit back??

No offense Bert :D
Besides thats as far now as i can probably go, make some drops then decide how keen you are on making then set off something that goes bang, unless you know energetic s well i can see alot of pain.

The drops are tough as seen in the film, but those tails break really easy, you break alot of drops at the start simply because the tails get caught or snag. Master the drop before thinking about explosives, unless you got the experience and knowledge of using them.


NEMO-Chemistry - 29-12-2017 at 16:40

Quote: Originally posted by argyrium  
It would be interesting to see what would happen if a drop was suspended in a mass of clear epoxy with only the tail sticking out. Once cured, snap the tail (at a distance).


I think it would be exactly like the lead in the video, nothing would happen, but then that kind of proves Berts on the right track.
If nothing happens then it has to be because the wave is absorbed? it dissipates over a bigger area, i think the idea is the bead delivers the energy to a single point?

BTW i doubt to get any emails back until at least end of first week in Jan. Not sure when the uni's go back

NEMO-Chemistry - 30-12-2017 at 02:09

Just a thought, not sure its a good test anyway but. What is the name of the purple stuff that has iodine in it? you paint it on wet and once dry it goes pop with little pressure? Might be worth some of us starting with small amounts of something like that.

But then again it goes off with little provocation, i cant remember the name now sorry.

j_sum1 - 30-12-2017 at 02:20

Nitrogen triiodide.
It goes off without being asked to as well.




Hmmm. Might be a fun thing to do some time soon.

Morgan - 30-12-2017 at 06:07

In passing, there's a lot of force in an ice bomb too, if there were a way to use the energy.

Ice Bomb
https://www.youtube.com/watch?v=uE_fhooANhE

NEMO-Chemistry - 30-12-2017 at 10:21

Quote: Originally posted by j_sum1  
Nitrogen triiodide.
It goes off without being asked to as well.




Hmmm. Might be a fun thing to do some time soon.


Thank you, i couldnt think of the name!!! Not a good choice if its impolite and does its own thing! I was trying to think of something sensitive but reasonably safe, and moderately legal in the UK.

I might try it out of interest, a small coat on the top shouldnt damage the drop if it goes off.

There was a UK program mainly aimed at kids (Brainiac), one the guys on the show, used to walk around with a paint can full, he would paint the inside of cupboard doors so they went off when people opened them!

Might try to find a video of an episode just to check its the same stuff.

Bert - 30-12-2017 at 12:22

Painted the inside of cupboards as a joke? Not a joke your victim would survive if that were literally true, and the idea of a paint can full is insane.

A couple of grams was enough to ruin the stuff on my desk top as a child.

It CAN go off while wet. The nice purple smoke hanging after it goes off is elemental Iodine, not something good to breathe

This material is decidedly in the category of "everyone who tries it has an accident".

It goes off from the vibration of closing a door to the room it was drying in. You can't safely move it when it is dry.

[Edited on 31-12-2017 by Bert]

aga - 30-12-2017 at 13:12

Quote: Originally posted by NEMO-Chemistry  
Erm thats exactly what i have done!

Put your photos or videos, or just the Scientific Data where your mouth is.

googled references to other people's physical work does not count as your own work, at all.

Bert is excused from Doing mostly for coming up with the idea, also because he is a real person with a real life.

Perhaps the implications are obscured by the sexy explosives angle, however a sudden non-incendiary energy release can be utilised for other things, such as sintering.

Edit:

NI3 is idiocy embodied.

[Edited on 30-12-2017 by aga]

NEMO-Chemistry - 30-12-2017 at 19:36

Quote: Originally posted by aga  
Quote: Originally posted by NEMO-Chemistry  
Erm thats exactly what i have done!

Put your photos or videos, or just the Scientific Data where your mouth is.

googled references to other people's physical work does not count as your own work, at all.

Bert is excused from Doing mostly for coming up with the idea, also because he is a real person with a real life.

Perhaps the implications are obscured by the sexy explosives angle, however a sudden non-incendiary energy release can be utilised for other things, such as sintering.

Edit:

NI3 is idiocy embodied.

[Edited on 30-12-2017 by aga]


I did put my OWN observations up! including the bit of where the tail starts etc etc etc. I also trawled papers to find data that might be helpful.

Nearly every post you make includes a plea for pics. Please give it a rest, not everyone has a phone that takes decent pics, some of us have access to good cameras, but i am not real comfortable taking an expensive camera that isnt mine into the lab!

The bit about Bert is bollocks, in the coffee thread i am doing your banging on about just doing it and taking pics, but surely seeing as i started the thread i must be exempt from that then?

I didnt google the bit about test tube glass stinging or.....
Fuckit, tell you what i will leave you to it.

You might be happy just going into the shed and seeing what happens, personally i dont have the money to waste chemicals, my own style is to research and ask questions first. Thats how I personally learn, if your not happy with what i post then dont read it.

If Bert has a problem with me writing to researchers, and posting relevant papers then the moment he tells me to stop i will.

You seriously think those papers were just randomly picked from google? No i read them first and check if they have anything relevant to what others have posted, or if they back what I have seen when i have tried stuff.

Seriously though i would really like to know what your obsession with having pictures is about?

Out of interest, just how much useful information have YOU contributed to this thread so far?

Maybe you missed the bit where Bert mentions googling is fine? It dosnt take long after you have a break before your back trying to shape the forum to the way you want it.

I learn alot on here, some of it from you, but the constant moaning and badgering is getting right on my tits.

I will post any replies i get to the emails but thats it in this thread for me.

aga - 31-12-2017 at 03:25

Yeah, you're right.

I'll not mention it again.

Sorry for spoiling your fun.

unionised - 31-12-2017 at 03:45

Quote: Originally posted by Morgan  
In passing, there's a lot of force in an ice bomb too, if there were a way to use the energy.

Ice Bomb
https://www.youtube.com/watch?v=uE_fhooANhE

They do.
https://diy.stackexchange.com/questions/90134/how-can-i-brea...

NEMO-Chemistry - 31-12-2017 at 04:27

Quote: Originally posted by aga  
Yeah, you're right.

I'll not mention it again.

Sorry for spoiling your fun.


Probably not (right i mean), i took my frustration out on you. Not getting as far as i wanted with the coffee, pictures are a really sore point at the moment but that isnt your fault.

If i ever finish what I am upto, your get a good idea why i am so frustrated. BTW, ever wondered why Caffeine yields are always so bad? Well i am discovering extraction isnt as straight forward as all the videos make it. But this is off topic here.


Rocinante - 31-12-2017 at 10:57

Yep, encountered the same problem. Use instant coffee, it's about 2.5 % caffeine by weight, this should help.

aga - 1-1-2018 at 07:57

Just had a got at making some droppings.

5 times a droplet formed, fell off and dropped into a bucket of water.

Each time they droplet solidified then quickly fractured and fell to bits, so a complete failure.

More to this than just heating glass it seems.

Edit:

Seems the trick is to heat the blob a lot more than the tail : https://www.youtube.com/watch?v=ASa7OSDx41k

[Edited on 1-1-2018 by aga]

NEMO-Chemistry - 1-1-2018 at 08:55

Also aga one the papers mentions this, apparently the water is best at a certain depth. This is so the glass can form a good skin before hitting the bottom, the glass then glows orange for a while when sitting on the bottom.

The tail as far as I know dosnt need heating, the blob just falls off and drags a tail with it. I am out of Propane (fuck its expensive!! 3.8KG £15!!), i will grab a new bottle when i get into town on weds.

Morgan - 1-1-2018 at 16:20

Is it possible to heat the center of a tube forming a blob and then quickly pull it from both ends so as to make a two-tailed drop, maybe lowering the sagging drop into a bucket as the two thin strands that support it are about to separate and break off from the two ends you are holding? Maybe it could be a two man operation to pull it off.

NEMO-Chemistry - 1-1-2018 at 16:57

Quote: Originally posted by aga  
Just had a got at making some droppings.

5 times a droplet formed, fell off and dropped into a bucket of water.

Each time they droplet solidified then quickly fractured and fell to bits, so a complete failure.

More to this than just heating glass it seems.

Edit:

Seems the trick is to heat the blob a lot more than the tail : https://www.youtube.com/watch?v=ASa7OSDx41k

[Edited on 1-1-2018 by aga]


Just had a good look at the video, there is a couple of things that look 'wrong'. For a start the colour refraction into the tail dosnt look right, from the best drops i have seen, the rainbow type reflection ends just before the tail starts.

Then look at the way the drop breaks, in the video there are chunks of glass, again with the best drops you get a fine powder.

It could be because he has used hollow glass tube, i dont know as i didnt try tube. But i think the video might be a good example of what we are not wanting?

Anyone else got thoughts on this? Especially the powder part? I am thinking the finer the powder formed, the more 'power' was involved when the drop exploded.

My gut feeling is still one of Bert is onto something with this.

Morgan - 1-1-2018 at 18:00

Maybe getting the glass as hot as possible produces the best powder shatter effect, creating more stress in the glass as it hardens.
I had a go at making some just now using boro tubing although I haven't broken the two small ones that formed. I didn't notice it at first but both had a very long spiderweb tail, one about 30 cm long at least that almost floated in the air being so thin. When trying to photograph it part of it broke off as it kept sticking to my hand without affecting the drop.
In the photo with the glass loop tail, I'm holding the Rupert drop out of the frame to just show the tail that was even longer before this photo.


DSC_0013.JPG - 229kB DSC_0008.JPG - 171kB DSC_0006.JPG - 185kB DSC_0004.JPG - 201kB DSC_0002.JPG - 258kB DSC_0015.JPG - 220kB

[Edited on 2-1-2018 by Morgan]

aga - 1-1-2018 at 23:42

Awesome !

NEMO-Chemistry - 2-1-2018 at 06:01

I hope to get another gas cylinder today or tomorrow, I hadnt spotted a small leak! Which explains how I got through so much gas so quickly!

I wont be making drops for at least 4-5 days though, my lab needs sorting and i got other stuff i want to finish!! Plus after tomorrow some pics showing my new upgraded indoor lab! No fume hood in that one, and it isnt any warmer though lol. But its mainly for the biochem stuff. I wanted to separate the stuff I am doing.

But once i get that out the way, i am back on the drops!

aga - 2-1-2018 at 07:14

Today i tried both borosilicate sirring rods, a smashed up jam jar and a window pane.

The jam jar glass got all bubbly rather than melting into a transparent blob.
The window pane just kept cracking and falling to bits before melting.
Stir-rods melted much more easily and were far easier to handle.

Making the tails seems easy enough, just the heads all broke up on cooling.

busted.jpg - 41kB

If anyone gets good at making the heads without a tail, i got spares ;)

Morgan - 2-1-2018 at 16:16

I've only attempted 4 drops but one was kind of lumpy when it separated from the tubing. As it fell into the water and cracked it seemed there wasn't enough homogeneity to the shape and uneven stresses may have caused it to fracture. Rotating the tubing as the blob formed with not enough heat to really melt the glass thoroughly, it just kept sagging and it may be that a hotter flame would be easier to get a uniform melt and thus less cracking on cooling.
I started out with a basic propane torch with a pencil flame and then used another torch with a slightly more bushy flame, neither of which lent itself to doing any borosilicate melting in a timely manner, even using two at the same time, finally settling on MAPP gas and that piezo spark torch head with the noisy flame. If I had a choice, I'd opt for a propane/oxygen flame or acetylene.

Trying to melt some obsidian collected from Oregon, I noticed it's really hard to melt and it shatters like ordinary glass unless I guess you slowly walk the temperature up.

NEMO-Chemistry - 2-1-2018 at 16:47

Quote: Originally posted by Bert  
Painted the inside of cupboards as a joke? Not a joke your victim would survive if that were literally true, and the idea of a paint can full is insane.

A couple of grams was enough to ruin the stuff on my desk top as a child.

It CAN go off while wet. The nice purple smoke hanging after it goes off is elemental Iodine, not something good to breathe

This material is decidedly in the category of "everyone who tries it has an accident".

It goes off from the vibration of closing a door to the room it was drying in. You can't safely move it when it is dry.

[Edited on 31-12-2017 by Bert]


He was on most episodes, his name is peter Logan.

https://www.youtube.com/watch?v=F0-jq2eJBYA

Watch from 19:34 for a min or 2, that episode is pretty mild. In some of them you see the can nearly full and he puts loads on under carpets etc. I remember the program from way back! It was a kind of science program for kids!!

Except once you start learning science you realize the program is shit!! They even tell you its made from Iodine and " one other secret chemical". didnt take long for people to figure out what that was!

I guess his victims got lucky, you can see from the reactions they didnt know what was coming.

Morgan - 2-1-2018 at 19:40

Saw this one tonight with very long tails.
https://www.youtube.com/watch?v=v8OK2FC440w
And this one with a Leidenfrost Rupert drop in slow motion nicely done.
https://www.youtube.com/watch?v=1z5rUvvRJuI#t=3m57s


[Edited on 3-1-2018 by Morgan]

Bert - 5-1-2018 at 09:31

If MAPP gas is marginal for working larger rods of glass, I am going to be needing a bigger torch. All I have now is a basic plumbers type propane torch, no Oxygen. Took a look at gas welding equipment, pricy... (we are all electric, have not touched oxy acetylene cutting or welding for years, since I cleverly managed to break both my ear drums and ended up in a river).

Years ago, I used propane with compressed air fed through a standard oxy acetylene torch body and a variety of large, flame spreading tips at the university physical science labs when working glass. It was adequate for quite large pieces and cheap.

[Edited on 5-1-2018 by Bert]

aga - 5-1-2018 at 11:04

Nice idea.

My tiny bottle of oxygen ran out earlier, yet i do have a compressor.

Will give it a try with butane.

Pray tell how the river, eardrums and oxy/acetylene became entwined.

Morgan - 5-1-2018 at 13:45

If you put a glass rod up the tailpipe of a pulse jet, you could probably melt it that way. And by some means if the ejected blob-like mass was captured in a nearby bucket of water below the exhaust, maybe there'd be a chance to form some drops akin to how volcanoes sometime eject glassy fragments into the air that cool into such shapes. Well, it looks good on paper. ha
https://www.youtube.com/watch?v=F8vqfphZ73A
https://books.google.com/books?id=Pt5QAAAAYAAJ&pg=PA42&a...

[Edited on 5-1-2018 by Morgan]

MineMan - 7-1-2018 at 21:01

Quote: Originally posted by Bert  
If MAPP gas is marginal for working larger rods of glass, I am going to be needing a bigger torch. All I have now is a basic plumbers type propane torch, no Oxygen. Took a look at gas welding equipment, pricy... (we are all electric, have not touched oxy acetylene cutting or welding for years, since I cleverly managed to break both my ear drums and ended up in a river).

Years ago, I used propane with compressed air fed through a standard oxy acetylene torch body and a variety of large, flame spreading tips at the university physical science labs when working glass. It was adequate for quite large pieces and cheap.

[Edited on 5-1-2018 by Bert]


Bert, a swirl torch with MAPP should do fine. The swirl torch flame hugs the rod even on the backside. They are 30-50 dollars at home depo, the swirl design really does work quite better than a standard design, it is somewhat new, last 5 years or so. If this is still not hot enough, which it should be, then placing some ceramic insulation around the part you are heating will make an amazing difference.

nitro-genes - 8-1-2018 at 12:06

Just made a few of these Ruperts drops from jam jar glass shards (prob. soda lime) and a propane burner. Very thin shards seem to work best, as larger shards form larger droplets and droplets larger than 6-7 mm seem to disintegrate gradually during the cooling in water, maybe exceeding its own tensile strength upon contraction. Got a few for which the tail broke off easily as well (without exploding the droplet). This seems to happen when the tail isn't cooled fast enough,which can easily happen, since it looses heat to the surroundings much faster than the larger droplet. When the tail of the droplet is heated a second time and allowed to cool slowly in the air, it can be broken off without the droplet exploding. Heating the entire droplet by pointing the flame upward slightly to heat the entire droplet (also the top) and keeping it just cm's from the cooling water to fall into works all the time. Was curious if they would behave similar when broken underwater, but they seem to do so, so any influence of resonance in the crack propagation as I mentioned earlier seems unlikely.

[Edited on 8-1-2018 by nitro-genes]

NeonPulse - 9-1-2018 at 00:05

Decided to have a go at this and got a couple of good ones but only from borosilicate glass. The sofa line I tried all disintegrated. I worked out that water needs to be cool but not cold. A couple of the ones I made appear to have a bubble in the end.

Anyway now we have the goods how do we go about getting this to work? Further up I read that maybe a tiny amount of primary could be used to bust the tail, setting off the drop which is placed in a small amount of confined ETN or other sensitive explosive. Is there an easy way to determine where is best to break the tail to give out the maximum energy to the explosive?

103F33F0-48E4-48E8-8ABF-BD057CD462AA.jpeg - 3.2MB

aga - 9-1-2018 at 02:28

Very nice indeed !
(jealous)

Morgan - 9-1-2018 at 07:53

Quote: Originally posted by NeonPulse  
Decided to have a go at this and got a couple of good ones but only from borosilicate glass. The sofa line I tried all disintegrated. I worked out that water needs to be cool but not cold. A couple of the ones I made appear to have a bubble in the end.

Anyway now we have the goods how do we go about getting this to work? Further up I read that maybe a tiny amount of primary could be used to bust the tail, setting off the drop which is placed in a small amount of confined ETN or other sensitive explosive. Is there an easy way to determine where is best to break the tail to give out the maximum energy to the explosive?


That one drop with the bubble right in the center reminded me of the evil eye, something I first saw and had as a young boy living on air force bases in Istanbul and Peshawar, and recently when I took a glassblowing class the teacher was making them. But just now I came across this attribute or supposed connection between evil eyes and Prince Rupert Drops. I'm sure most evil eyes aren't spring loaded of course, but it might be fun to try to make one that way. Funny to be led to this article by your "evil eye" drop. I had heard of the protective belief but not of the exploding property. You see I wondered if anyone had tried to make an evil eye Rupert drop as an artistic venture by coloring the glass and somehow strategic placement of a bubble - thus a search "evil eye rupert drop" in Google this article came up as the first hit.

"Local legend has it that if an evil person enters your shop or home, the evil eye will spontaneously shatter, warning the owner to the presence of an extremely evil person."
http://ieeexplore.ieee.org/document/1337917/

https://en.wikipedia.org/wiki/Evil_eye

[Edited on 9-1-2018 by Morgan]

Morgan - 13-1-2018 at 17:58

A few tidbits maybe of interest ...
How To Break a Wine Glass With Prince Rupert's Drop?
https://www.youtube.com/watch?v=akO6x5CF3f0

NEMO-Chemistry - 15-1-2018 at 05:19

Quote: Originally posted by Morgan  
A few tidbits maybe of interest ...
How To Break a Wine Glass With Prince Rupert's Drop?
https://www.youtube.com/watch?v=akO6x5CF3f0

8:21 shows exactly what your looking for. Notice how all the best ones break into a powder?

Good video, it looks like the way forward, is find out what method makes drops that powder when they go off.

NEMO-Chemistry - 15-1-2018 at 05:23

Quote: Originally posted by NeonPulse  
Decided to have a go at this and got a couple of good ones but only from borosilicate glass. The sofa line I tried all disintegrated. I worked out that water needs to be cool but not cold. A couple of the ones I made appear to have a bubble in the end.

Anyway now we have the goods how do we go about getting this to work? Further up I read that maybe a tiny amount of primary could be used to bust the tail, setting off the drop which is placed in a small amount of confined ETN or other sensitive explosive. Is there an easy way to determine where is best to break the tail to give out the maximum energy to the explosive?


If you look at the drop, you see where the rainbow colour ends as the drop start to form the tale. Directly behind that point is where they give the best break.

If you break them too far from the rainbow colour (stress point), then they dont break well, you get more of a shatter and larger particles, or it dosnt break the drop at all.

Make sure you got good eye protection! Actually working in water is not a bad idea.

[Edited on 15-1-2018 by NEMO-Chemistry]

symboom - 15-1-2018 at 07:27

Now the question is what can it set off from the glass explosion does it create a shockwave
Could it set off ammonium nitrate with sensitizer
Possible ones that are sensitive enough
With even Armstrong. Mix

Methylammoniunm nitrate
Or rdx which is a secondary
By going of how fast the drop explodes

[Edited on 15-1-2018 by symboom]

Morgan - 15-1-2018 at 08:25

I wonder if you mixed in some higher melting point chopped fused quartz wool into ordinary soda lime glass and then made drops from that, how would the fibers affect the drop? Seems like it might dampen the effect if you could make them from that but who knows.

Bert - 15-1-2018 at 08:30

MAPP torch should arrive tomorrow, I need to get my hands dirty.

NEMO-Chemistry - 17-1-2018 at 02:30

Quote: Originally posted by symboom  
Now the question is what can it set off from the glass explosion does it create a shockwave
Could it set off ammonium nitrate with sensitizer
Possible ones that are sensitive enough
With even Armstrong. Mix

Methylammoniunm nitrate
Or rdx which is a secondary
By going of how fast the drop explodes

[Edited on 15-1-2018 by symboom]


If you study that last video really carefully, you notice it has one hell of a shockwave, its the shockwave you see travel up the drop, then as soon as it touches the glass the glass breaks.

At first i thought it was more to do with the glass being at the right frequency, but the fact the glass has water in as well, that should have dampened or altered the resonate frequencies, shouldnt it?

So if thats the case then the high speed film shows an enormous amount of power for a split second. I noticed with the few drops I have made, those that glow in the water longest give the best results.

When they break, you can tell when you got it right by the powder formed. The finer the powder the better the drop. Those are the ones that sting lol.

The way the glass the bead is in breaks, I would think these would be more than capable of setting something off. I have a piezo electric strip, setting it up so the bead touches it, the attaching it to an Oscilloscope, should gigve an idea how much force is there.

I suspect one of those piezo electric wafers, used in electronic drum kits, would also give a good idea of the energy produced.

I think for me thats the path I will go down, i can experiment with that, I dont think it makes any sense for me personally to use anything that goes bang.

I know your looking to set off primaries, but with the test above, i should be able to compare what makes the best drop. So maybe next job is find a way to make a more standard sized drop.

Also the break point on the tail seems important, but that could be coincidence. All these high speed films are really goo information.

I would love the full files for these, and go through them frame by frame, the problem is by the time they are converted to youtube etc, i bet they have lost alot of information.

[Edited on 17-1-2018 by NEMO-Chemistry]

Morgan - 17-1-2018 at 07:17

Not all that exciting but it seems possible to "snap" a super saturated solution of sodium acetate into crystallizing using a Prince Rupert Drop instead of oil canning a metal disk in a heat pack.

symboom - 17-1-2018 at 15:37

Well primaries already are sensitive I was thinking if there was enough energy to even replace a primary to set of a less sensitive secondary compound it would be surprising if its possible.

Chemetix - 18-1-2018 at 21:38

I was watching a few youtube vids with P Ruperts drops being fired at by small arms, in slow mo of course. What stands out is the deflagration of the glass as being reasonably quick but not particularly energetic. The fragments don't seem to accelerate from the body of the fracture zone too fast, compared to the fragments of the projectile. I guess you are looking at the stored energy as an elastic potential in all but a small skin layer of the glass. Compared to the chemical energy stored in every molecule of a primary.

The energy density would be particularly low by comparison. I think there could be some novelty combination of substances that could form a detonation train to initiate a secondary via a P Ruperts, but then a Rube Golberg machine could too.

Morgan - 19-1-2018 at 07:40

Maybe I missed the discussion somewhere but the fracture speed "1600 meters per second… or 3579.1mph" is always highlighted along with the tons of force they can withstand but what speed do the glass fragments travel at? Seems like it should be mentioned next to the fracture speed to enhance the understanding.
"So the end result is an awesome explosion of glass shards in all directions."

https://fabstracts.wordpress.com/2013/10/22/dutch-tears/

There's this sandbox pod that's said to explode with a speed of 66 meters per second and an angular velocity of 15,000 rpm in once case. It can break windows and injure cattle when the pumpkin-shaped pod goes off with a bang. People in a forest have mistaken the explosions for gunfire.
It would be interesting to know how the angular speed of this seed compares to a Rupert Drop fragmenting? Or could you combine/idealize the angular speed with the forward speed akin to being on the worst side of a hurricane when it hits - a contribution of angular motion and forward speed.
Sandbox tree disperses its seeds via explosive method
https://www.youtube.com/watch?v=AKEgrmfHWX0

http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.1977....
http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.1977....

[Edited on 19-1-2018 by Morgan]

aga - 22-1-2018 at 07:51

Heuston, we have droppings !

2 cheapo butane/propane torches, a 250ml beaker of distilled water and a boro stirring rod worked first time, then three more times without fail.

drop1.jpg - 43kB
drop2.jpg - 43kB
drop3.jpg - 45kB

It took a lot longer than the oxy/butane torch, so maybe that made them too hot.

Now to see if they go *pop* when the tail gets snapped off.

Edit:

Bugger. Not one of them went *pop*.
Must need to be a lot hotter before dropping into the water.

[Edited on 22-1-2018 by aga]

aga - 14-2-2018 at 11:12

Found place locally that sells MAPP gas & torch !

torch.jpg - 33kB

Certainly melts the glass faster than the other stuff.

Pretty quickly got 3x drops:

drops.jpg - 40kB

Sticking them in a plastic bag and snipping off the tail did bugger all :(

cut.jpg - 40kB

Has anyone made one yet that works as advertised, i.e. explodes when the tail is snipped off ?

happyfooddance - 14-2-2018 at 11:57

Maybe try dropping them in oil, not water?

https://en.m.wikipedia.org/wiki/Leidenfrost_effect

aga - 14-2-2018 at 12:04

Nah.

It's about the skin cooling faster than the interior rather than just a skin effect.

I'll have another go tomoz.

The three i tried 20 mins ago were all dropped into the same pot of water.
The last one fell to bits and the first two seemed to explode, so it's looking better.

It seems easy to get a blob of tear-shaped glass, harder to get those internal stresses going on.

happyfooddance - 14-2-2018 at 12:15

How is the skin going to cool faster if water vapor is creating an insulating layer...?

If you want to create extra stress, you can start with soda-lime glass and do an ion exchange deal (Na->K), this is ubiquitous nowadays and I am sure you can find refs. for the process.

As for writing off my suggestion, you are one who is always saying it is worth a try. And I only mention it because I know it has worked for others... And you seem to be having little success.

How hard can it be to set up a pan of oil, aga?


Bert - 14-2-2018 at 12:28

The molten salts- What is a eutectic mix of reasonably cheap ones.

I recall that some people who make Lead shot at home by dripping molten Lead into liquid from far enough above to allow time for surface tension to pull the drop spherical and air flow to get the drop skinned over with solid Lead use glycol antifreeze for the liquid. They can tailor the hardness produced somewhat by the speed of the chill/temperature of the liquid in the bucket (faster chill = harder for Lead alloyed with Antimony/Tin/Arsenic- Why ammunition manufacturers tout their products as containing "chilled shot")

Drip a drop into a cup of glycol antifreeze just out of the refrigerator, that is, antifreeze without water admixture. No Leidenfrost effect? Go the other way- Room temperature quench? Just under smoke point quench?


[Edited on 14-2-2018 by Bert]

aga - 14-2-2018 at 12:34

Quote: Originally posted by happyfooddance  
How hard can it be to set up a pan of oil, aga?

Sorry, you're quite right. It's not hard to do at all.

I look forward to seeing your photos of Success on the morrow.

happyfooddance - 14-2-2018 at 12:55

Quote: Originally posted by aga  
Quote: Originally posted by happyfooddance  
How hard can it be to set up a pan of oil, aga?

Sorry, you're quite right. It's not hard to do at all.

I look forward to seeing your photos of Success on the morrow.


Bro, this is me trying to help you out with YOUR project. I for sure have my own projects, but I don't think they fit in this thread and I don't want to start a new one when I can UTSE just fine. Also, I am taking care of my 12 month oId son. But good luck with YOUR project.

Vomaturge - 14-2-2018 at 12:55

Here are some air-cooled "dud" glass drops, used as jewelry:
https://store.sundropjewelry.com/blogs/news/ive-heard-of-a-p...
Here's another from quenching in LN2 (low temperature, but low heat capacity/heat of vaporization, and lots of vapors to interfere with the cooling process:
http://www.scienceforums.com/topic/30128-molten-glass-droppe...
The quench conditions seem very important, and are an easy parameter to change. However, some of the experiments here have lead to the drops breaking during cooling. Perhaps the glass composition matters too? Do some glasses have more capacity to bend before breaking? It seems like the ultimate combination would be a high coefficient of thermal expansion, a moderate to high elastic/bulk modulus (so it would deform or compress only slightly for a given force), and the ability to flex a lot (for a glass bulb) before breaking. That way, the glass wouldn't shatter itself while cooling, but would have a lot of elastic energy stored inside.
Another thing, is that molten glass gets much less viscous as its temperature goes up. Could the temperature prior to hitting the water be a major parameter?

Bert - 14-2-2018 at 13:06

Regarding brittleness? Look in this table of materials for some clues.

https://www.makeitfrom.com/material-group/Glass-and-Glass-Ce...

Check the Poisson's ratio for your material- A higher number = less brittle.

For example:

Fused quartz = .17

Vycor "glass" = .19

Borosilicate glass (Schott brand) = .20

Soda lime glass = .23 (approximately, for annealed float glass, lots of variation)

Mild steel = .30 - .35

Rubber! = .45 - .5 (effectively, .5 is the limit)

I suspect the figures given for heat conduction would be of some interest here too.

aga - 14-2-2018 at 13:10

https://www.youtube.com/watch?v=0KaWSOlASWc

Lou Reid.

The relevant lyrics are at 1:23 to 1:41, then again at 3:17 to 3:44

aga - 15-2-2018 at 10:55

Had another go today, making 7 'drops', 4 out of borosilicate, 3 out of soda-glass (a smashed up drinking glass).

The borosilicate ones tend to easily form into a droplet, yet have zero activity.

The 'normal' glass doesn't crack up easily with the MAPP gas torch during heating, yet shatter after a few seconds in the water - the glass just cracks into bits before a droplet forms with a butane torch.

A random utoob comment says it is easier with soda-lime glass, although borosilicate glass can be done.

So far i think the soda-lime glass droplets are the way forwards, as they at least self-destruct at some point, i.e. after a few seconds, whereas the boro ones have done nothing so far.

Every attempt took at least 10 mins heating to get a droplet to form & fall into the water.

happyfooddance - 15-2-2018 at 12:21

Quote: Originally posted by aga  


Every attempt took at least 10 mins heating to get a droplet to form & fall into the water.


Sounds like you aren't using your torch properly. Tip of the blue, seems like good advice.

aga - 15-2-2018 at 12:34

Quote: Originally posted by happyfooddance  
Sounds like you aren't using your torch properly. Tip of the blue, seems like good advice.

To be honest i think you're absolutely right.

So far i've been clenching the torch in my bum-cheeks while suspended upside-down from a roof beam with the glass pieces held in my teeth.

Contorting to get the glass & flame to even get in contact has been really hard.

Lost both eyebrows yet only one load of nostril hair. Wish i had done more Yoga to get both.

For the next attempt i will take off the monkey trousers and the scuba flippers to see if that helps.

happyfooddance - 15-2-2018 at 12:37

Quote: Originally posted by aga  
Quote: Originally posted by happyfooddance  
Sounds like you aren't using your torch properly. Tip of the blue, seems like good advice.

To be honest i think you're absolutely right.

So far i've been clenching the torch in my bum-cheeks while suspended upside-down from a roof beam with the glass pieces held in my teeth.

Contorting to get the glass & flame to even get in contact has been really hard.

Lost both eyebrows yet only one load of nostril hair. Wish i had done more Yoga to get both.

For the next attempt i will take off the monkey trousers and the scuba flippers to see if that helps.


Maybe it would help if you just used the search engine.

Edit: or maybe drink less...???

[Edited on 2-15-2018 by happyfooddance]

aga - 15-2-2018 at 13:04

It'd help if people talk Less and Do more.

Unlikely that will happen in my experience.

I'll burn the rest of this MAPP canister to see if i can help Bert achieve at least a functional 'drop' so he can test if it can make other stuff go BOOM.

To be fair to Bert, who could/should be trying all this out, i'm personally too scared of explosives to go anywhere near what he proposed, so i'm really happy to be able to at least contribute to the Prince Rupert's Drop synthesis.

Glad Bert has Not wasted his time on the 'drop' part too much, as it is the most facile part of his idea, yet has proved elusive to ACTUALLY produce.

A google page does not equal a working method.

(one requires actual physical time and effort, the other just needs internet and desire to sputter words all over)

aga - 16-2-2018 at 11:22

A lot of searching turned up endless piles of droppings with hardly any real info at all.

Presumably happyfooddance's oil suggestion comes from a brief passage in GlassWorking_OCR.pdf which can be found in the SM library.

"The drops of glass produced by Prince Rupert of Bavaria by dropping molten glass into oil"

None of the dozens of other references found suggest oil - they all say water.

A utoob vid shows a method by which the drops are formed without touching the sides of the water container at all.

https://www.youtube.com/watch?v=8p5fnM1hcCY
(it's in German)

A random comment at http://www.instructables.com/id/Make-Prince-Ruperts-Drops-Gl...

"For those wondering, yes, you can make the drops from Boro (Pyrex) however, unlike soft glass or soda glass, they will not explode."

kinda suggests that lab glass is not a good way to go. Other random comments elsewhere either say the same, or that it is much harder to get to work.

Finally some actual Science was found here: http://www.livebinders.com/play/play?id=1997855

While the work does not discuss how to form the drops, the materials were 'feldspar' for the glass, and the data suggests that either boiling water or ice cold water works much better than water at 26 C, which is what it's been here recently.

Another thought is that while glass is pretty crappy at conducting heat, it might be a good idea to reduce the mass to be heated, also disconnect it (thermally) from whatever it is being supported by.

So, for tomorrow's attempt(s) i'll be trying :-

Ice cold water
A smashed up jam-jar (soda-lime glass)
Once melting, pull the glass above where the bead will form to make a thinner connection
Heat only the bead, not the bit above it
Remove heat once the beat starts to descend, so as to let it go into the water without fully disconnecting from the supporting mass.

That last bit should let it become immersed without letting it touch the side or bottom of the glass of water.

Fyndium - 29-8-2021 at 10:15

Using NaOH solution in place of mere water should reduce leidenfrost effect. I have used this lye quench method successfully to harden normal 1010 steel, which can not be done with brine or water.

Laboratory of Liptakov - 20-9-2021 at 11:40

According this video, the Ruperts drops has not any intiation power. https://www.youtube.com/watch?v=mw_-EBgBYFk
Small drops even no damage the skin between fingers. time 3:08
I guess, this drops is nonsense use for initioation secondary EM.