Dragon Eggs: CuO and Al/Mg

[scarletmanuka]

While reading a thermite thread, I came across dragon eggs as a small binded CuO or Pb3O4 with Magnalium star, which exploded unconfined. I was unable to find any more information on construction, so I decided to try and make my own. I went to a ceramics supplier and bought 50og of Black CopperOxide and 100g of Al lining. I tried to get Pb3O4 or red lead, but it was discontinued.
My first mix was a stoich mix of CuO and flake airfloat Al which burned very violently, but was insensitive to any form of fuse. So I then made a comp consisting of a stoich CuO and hand filed Magnesium which ignited more easily, but did not burn as quickly. My mixing these two as 50/50 and binding with NC, I was able to mould micro balls 2mm across which would explode with a loud report went ignited.
I have also prepared some dragon eggs which are bound with clingwrap (chlorine donor) dissolved in acetone to see if I can achieve a blue flash. I will try this when it gets dark.

[blindreeper]

Are you trying to say that a 50/50 mix of CuO and Mg powders binded with NC will make a crackle star :eek: I thought you had to use bitsmith or lead oxides! This is great, CuO is made very easily by CuSO4 + 2 NaOH -> Cu(OH)2 + Na2SO4 then Cu(OH)2 +h heat -> CuO + H2O
Very cheap for the CuO. Pity about the Al not being flame sensative, when it ignighted did it have the same crackling effect as the Mg based stars? I think a good hot prime may do it the trick.

About the clingwrap (glad brand I assume) what is made of that has chlorine in it? I don't think its PVC although I may be worng.

Look forward to tests, pictures and results! Crackle stars are among my favourite effects in fireworks and have always wanted to make them. Good work!

[Bert]

Yes, Copper oxide will replace the other oxides such as Lead tetroxide or Bismuth trioxide. Below is an e-mail I got from someone who did some experimentation with these.
---------------------------------------------------------------------------------------------------------
Modified Dragons' Egg formulation:

37.5 g. Bismuth Trioxide (Skylighter)
37.5 g. Copper II Oxide (Clay Art Center)
25.0 g. Magnalium (275 mesh, Skylighter)
+20 g. Winchester 231 Double Base Nitrocellulose solution.*
*Solution of 20% W231 to the following solvent mixture: 30% Acetone 70%
Amyl Acetate all by weight.

Procedure:

Weigh out Copper Oxide and Bismuth Oxide, add Copper Oxide first to wide
mouth plastic container with screw-on lid, then screen Bismuth Oxide
into container (I used a fine stainless Tea strainer). Screw on lid and
then shake container to mix ingredients. Now weigh out Magnalium and add
to container, replace lid and shake container (caution should be used as
this is now a very sensitive mixture) to mix. Weigh out and add the 20%
solution of the Double Base Nitro Cellulose, mix using a wooden dowel.
This should form a nice "play dough" consistency when removed from
container and kneaded between gloved hands. Rollout onto waxed paper to
1/8" thick, then cut into 3/16" squares. Let dry for 5-7 days in well
ventilated location.

Once dry, the cubes are broken up into individual squares. They are then
primed using the following mixture:

58 g. Potassium Perchlorate (Chinese, Skylighter)
21 g. Charcoal (ground in a coffee mill and screened to -20 mesh)
4.0 g. Potassium Dichromate
4.0 g. Red Iron Oxide
4.0 g. Red Gum

Solvent used was 90% Isopropyl Alcohol. Stars were rolled until prime
was about 1/16" to 1/8" thick. Stars dried for one week.

Effect:

These stars will often detonate in a bright, single, very large
explosion almost immediately following ignition; they may be rolled with
a delay layer if a short delay is desired prior to detonation. Some will
detonate multiple times, up to four have been observed by myself, but
they are still much louder then the "classic" Dragons' Egg formulations
using either Lead or Bismuth Oxides.
----------------------------------------------------------------------------------------

Some later communications indicated that there was little change in performance when he replaced varying ammounts of the Bismuth trioxide with an ammount of Copper oxide to provide an equal ammount of O2- The expensive/toxic Bismuth or Lead oxides aren't needed, apparently.

[Guerilla]

About the clingwrap (glad brand I assume) what is made of that has chlorine in it? I don't think its PVC although I may be worng. Some brands can contain PVC, but those used for wrapping groceries are most likely manufactured from Saran (polyvinylidene chloride, (C2H2Cl2)n). It has a chlorine content of 75%, while PVC 57%.. scarletmanuka, how well did your clingwrap dissolve in acetone? Mine only became somewhat soft and 'rubber-like' but didnt dissolve.

[Crazy Swede]

The substitute for read lead (Pb3O4) in crackling stars is bismuth trioxide (Bi2O3).

The Chineese often claim that their crackling stars only are based on CuO, MgAl and a binder, sometimes also some KNO3 and S. But I have actually never really trusted their composition sheets that followed the products we imported.

Anyway, Shimizu, Jennings-White and others have shown that it is possible to achive crackling effects from microstars without the use of Pb2O3 or Bi2O3!

[blindreeper]

Crazy swede, could you please reproduce those sheets here or post what forumulae they used with the CuO based and the KNO3/S based crackling stars?

[Blackhawk]

Yes it does sound very promising, I'm concentrating on LE's for a while and I love crackling stars effects too, but the pfp only gives the lead and bismuth versions. Would be good if the CuO Al stars crackled the same as the Mg ones, as Blindreeper said a hot prime would probably light them, I assume the stars would be pressed into a slug 'star' of meal powder to make sure they all light over a length of time after being fired rather than all at once, this would probably act as enough of a prime, although you could add things to the meal powder to increase the burn temperature.

[Crazy Swede]

From a quick glance at the old product sheets from China, i found the following fomulas:

32% CuO
60% MgAl
8 % Dextrin

15% KNO3
26% CuO
28% MgAl
21% Fe (!)
7% Charcoal
3% S

I really doubt the latter could work. Also, it sums to 102% and lacks any binder. But, the former one might have some potential. Please inform us of any positive results!

I made a mistake when I claimed that Shimizu and others have shown that crackling effects can be achieved without lead or bismuth oxides. What they have shown is that you can make micro stars with a delayed flash, but without the characteristic crackling sound. Sorry!

[Bert]

The first comp. is similar to what others have reported to work, but with NC for a binder instead of dextrin. I'm going to have to play with these when I get a minute! I'm building equipment for next summers shows, don't have any time for experimenting. Not to mention how cold it is.

[scarletmanuka]

I have had success with CuO and Al, by adding a little KMnO4 to increase flame sensitivity. The only problem with this is that if the balls get to big ie>2mm it loses the really sharp report. The other interesting thing that happened, was that when I added the KMnO4 to the really thin NC Lacquer (0.04 grams to 8mL) the whole solution coagulated into a very thick jelly which made it very hard to stir in the thermite mix. One advantage of this though, is that leaving it to dry will produce round nuggets about 4mm across, which are then just cut in half with a pair of scissors. These however are not quiet as loud or bright as the Magnalium ones.
The clingwrap worked well as a binder, but did not produce a blue flash, I used 5% as a binder and it was virtually indistinguishable from the NC bound stars. I think however it would be advantageous to prime the stars, because if I ignite a large amount in a tube, I do not get the crackling effect, but rather a loud deep boom with a beautiful brown smoke ring.
I am also convinced that stoich is not the best formula, after igniting some on a tile, ther was always a large amount of excess CuO present as black scorch marks. Interestingly enough, after igniting some of the lose mix on a tile, there was left a beautiful crimson scorch mark with green and blue edges.

[T_Pyro]

Just some clarification: clingwrap (at least the variety found here) is made of LLDP (linear low density polyethylene), not saran or PVC. There is no chlorine at all in LLDPE, so the theory of it acting as a chlorine donor can be ruled out.

[scarletmanuka]

Well that would be why it didnt work then. The blue colour that is. Still makes a nice plasticiser though.

[Agent Blak]

If a very brief dely coating and a bit of bp were added you you could makesof shelled FlashBangs. The multiple bangs coming from varied locations would be very disorienting. For a delay a dip in thin NC and a Meal Powder dusting, then Repeat.

But my mind is kind of always focussed in the weapons direction,:cool:

[Evil_Tree]

From a quick glance at the old product sheets from China, i found the following fomulas:

32% CuO
60% MgAl
8 % Dextrin



Will Dextrin bind CuO and MgAl properly? Wouldn't it have to be wet, resulting in a posible reaction between the MgAl and water?

[Bert]

Will Dextrin bind CuO and MgAl properly?

When I've made them, I bound the crackle granules with nitrocellulose dissolved in either acetone or amyl acetate. The black powder type composition matrix the crackling granules are embedded in to make up the "dragon eggs" are bound with dextrin and water, however. If you make the crackle granules with a water soluble binder, they may crumble into the mix and defeat the purpose of the whole project.

[nesler]

Some dragon egg comps that might prove to be useful:
(Argh...damn thing screws up spaces...)
Swisher 1988

Pb3O4-----------------------89%
Mg/Al, 50:50, 100 mesh------11%
bind with 10% NC or 6% dextrin

Stevens
Pb3O4-----------------------10
CuO--------------------------7
Mg/Al 50:50, 100-200 mesh----4
KNO3------------------------1.5
S-----------------------------1
bind with dextrin or NC

Shimizu

-----------------------------A------B ------C------D
Pb3O4----------------------84.2----90-----89-----90
Mg/Al 50:50, < 80 Mesh-----11.2------------11------
Mg < 60 Mesh--------------------------------------2
Al 60-100 Mesh----------------------10------------8
CuO-------------------------4.6

A - nice crackling
B - less crackling
C - active but not loud crackling
D - less crackling, but a few very loud crackles

Best of AFN III, AK

Pb3O4-------------------------81.8
Mg/Al 50:50, 100-200 mesh------9.1
CuO----------------------------9.1
bind with 10% NC

[nbk2000]

These "dragon egg" pellets make for a good filler for flash-bang type grenades, as the sparks just fly everywhere. :)

Though they're rather expensive to buy pre-made. But $3 worth is enough for one grenade filling.

Just waiting for the 4th of July to roll around so I can stock up this year. :D That, and roman candles. ;)

[Sparky]

I saw this thread and thought I should try to make dragon eggs with CuO/Al mix and CuO/Mg mix, bound with NC.

Stoichiometric is probably the fastest burning, or at least close to fastest so that's what was used. 81.5% fine ceramics grade CuO and 18.5 Al 8 micron dark indian aluminum. This was mixed dry first, then with fairly thick NC/acetone laquer (I'm not sure how concentrated it was) until it was pourable. Then this mixture was poured out into thin strips about 2mm wide and when dried broken up into small pieces. Some of these pieces were mixed with some rough BP and lit. No crackling sound, just small poofs. The nitrocellulose was slow burning 12% nitrogen from firefox.

The same thing was done with the copper (II) oxide and magnesium powder. The stoichiometric mix was determined to be around 77% copper oxide and 33% magnesium. The magnesium was ball milled from 325 mesh so the end particle size was of course smaller than 325 mesh.

Laquer too thick/too much? Metals too fine? Should magnalium be tried (325 and/or 200 mesh)? I don't know. Could people who have succeded in making the dragon eggs compare their method/materials used to that written here?

BTW, what do other people keep their NC laquer in? A mason jar seems to let the acetone evaporate slowly out, concentrating the solution.

[nesler]

To quote Crazy Swede:
What [Shimizu and others] have shown is that you can make micro stars [without lead or bismuth oxides] with a delayed flash, but without the characteristic crackling sound. Sorry!

So basically, if you only use a mix of CuO and Al or Mg, you're never going to get a satisfactory Dragon's Egg. Not to be a critic, but how did you miss those critical ingredients?

[FrankRizzo]

From a post on USENET a few years ago:


From: Tom Perigrin (tip@mercury.aichem.arizona.edu)
Subject: Dragons Eggs
Newsgroups: rec.pyrotechnics
View complete thread (45 articles)
Date: 1995/09/07




A while ago Lloyd asked about dragon's eggs.

Dragons eggs are clever little bits of chemistry that seem to work through
the diffusion of a gaseous oxidizing agent into a layer of reactive metal.
This sets the stage for a very fast reaction (Shimizu calls it a
detonation) in a thin layer along the leading edge.

According to Shimizu (Pyrotechnia XIII, p10, 1990), the first reaction is a
dark reaction wherein Pb3O4 reacts with either Al or Mg/Al to give Al2O3 or
MgO, and PbO. The PbO boils at 1470 C, and can diffuse into the loosely
packed Pb3O4, Mg/Al, NC binder layer. As the PbO accumulates around the
Mg/Al, the PbO and Al partake in a high energy reaction which seems
particularly sensitive to initiation via shock.

There are a large number of forumations for Dragons Eggs, and there seems
to be a wide latitude in which the formulations "perform". However, not
all formulations perform equally well. This is probably affected by the
specific conditions in any individuals lab, and so the formulas should be
thought of as initial guidelines.


Evidentially, the PbO plays an important part in the chemistry involved with making the sharp report.

[Sparky]

The more I read the more it seems using only copper oxide won't work, but I am still hoping.

nestler, I see what you mean but other people in the thread seem to be saying that you can make dragon eggs with only CuO as the oxidizer. The quote says you can make the microstars without the crackle but doesn't say you cannot make CuO/Al stars with crackle (though it implies it, I am still hoping ;)).

I converted the formula posted by Bert to using only copper oxide, providing the same amount of oxygen. I found it to be:
50.8 g CuO
25.0 g MgAl
+20 g. Winchester 231 Double Base Nitrocellulose solution.

Which is convenient since it is basically 2:1 CuO:MgAl. The nitrocellulose I have is quite different, which is which I haven't tried the above yet. Obviously this mixture has far less copper oxide than the mixture posted by Crazy Swede, so I suppose that is a good indication that one of them won't work, probably the one with little CuO since it's origin seems iffy.

I notice also that Scarletmanuka used "very thin" 0.5% laquer while I used quite thick stuff. Hopefully that is my problem.

From reading a post on rec.pyrotechnics it seems coarser 50- 100 mesh MgAl is better than finer 200 mesh so perhaps there I screwed that up also by using metals that are far too fine.

[Bert]

I converted the formula posted by Bert to using only copper oxide, providing the same amount of oxygen.

I'm afraid you'll need some Lead tetroxide or Bismuth trioxide if you want more than just a flash- Al and CuO are just a thermite mix. You can use it for a flash & report mix in a salute caseing if they're fine enough particle size, but they won't go bang just bound with NC and burned in the open!

Some Chinese formulations are bound with other plastic resin systems than NC- The binder doesn't seem to be the critical ingredient. WW 231 was just an easily available material that gave a good result.

[blindreeper]

What about the PbO2 out of car batteries? There is a decent amount in them. Empty out the sulfuric acid out and flush the battery with lots of water. Open it up (I resorted to an axe and a hack saw last time I opened one up!) and break up the PbO2 plates. They are usually very fragile and break apart easily so thats a start to getting a powder. Put the PbO2 into a bucket with a solution of bicarb or carbonate whichever is easier. Filter and there you have some nice PbO2.

Assuming that you can use the dioxide in place of the tetraoxide we would be rolling :)

[nesler]

Not to be a critic, but Sparky, this seems to be a major exercise in futility. Everything I've read seems to indicate that Lead Or Bismuth Oxide is necessary. Just take your time, and track down the necessary chemicals.

[Guerilla]

Paint stores are good places to look for lead oxides. Pb3O4 and PbO at least are used widely as undercoat paint additives for iron surfaces. They may be regulated in some places though due to their toxicity.

[Bert]

They may be regulated in some places though due to their toxicity.
Banned from commercial paint in the US since the 70's. Several auctions of these on eBay though-

[nbk2000]

A formulation that only flashes, without noise, would also have some utility in diversionary devices.

[Bert]

A formulation that only flashes, without noise, would also have some utility in diversionary devices.

The dragon egg granules are probably a bit small for tactical use.

An easy way is to make a flash salute with thin walls, and mix the flash 50:50 by volume with fine sawdust. Not entirely noiseless, but can be tuned pretty darn quiet- Mixing the flash used a bit higher than normal on metal helps too.

[nbk2000]

Is there a size limit to how large the dragon eggs can be?

Even if they can't be larger than a BB, that's still useful as you can disperse a cloud of them into a twinkling sphere of dazzling fireflys that'll burn spots into night-adapted eyes (or shut off an NVD), making them easy pickings, without a lot of noise to attract attention.

After all, it's much easier to control light emissions from a space than sound.

[Bert]

Is there a size limit to how large the dragon eggs can be?

Yes. at about 3-4mm or so, they stop exploding completely and break up into several smaller chunks that blow up at random times after the first partial explosion. I don't know how the formulation without the Lead or Bismuth oxides might behave in this regard.

Micro stars with delayed flashing can be made several other ways as well, if the audible crackle isn't needed.

[blindreeper]

I have been doing a bit of experimenting with these comps. I have tried CuO/Al (-324 mesh spherical) which needed a sparkler to ignight when formed into micro stars. Then I kinda gave up on these until I got some Mg :) The Mg is -325 mesh spherical and with a 50/50 CuO/Mg mix it burns rather fast but no crackles in a powder. I tried cutting the Mg with 50% -325 mesh spherical aluminium and I didn't notice a difference in performance. Both of these ignited with black match which would make it fine for a core without a prime.

Next I tried 50/50 with CuO and a new flake aluminium I obtained at a paint store which is extremely fine and makes your hands silver. Opening the tin results in it floating away :) It is so light and fluffy! This burnt very well and bright, sensative to a piece of black match as well. Then I tried 50/25/25 CuO/Mg/Flake Al and that burnt much the same only slightly faster.

Note all of these were done in powders not made into micro stars except the CuO/Spherical Al one which didn't crackle.

In conclusion the Aluminium particle size plays a big role. If you can afford the Mg go with it cut with Al. These should provide great cores for rounds stars.

I will report about how the CuO/Flake Al go as micro stars as far as crackling goes.