25 replies to this topic

[Jimmymcknife]

Hi everyone, i'll just say that this is one of my first posts but i have been reading here for a while and all the information and collected experience has really helped meout developing my hobbt, so thatks..

On to the subject in hand: i recently made a batch of dragons eggs, the formula was from pyroguide and is a s follows:

Lead Tetraoxide 44
Copper Oxide 31
Magnalium 17
Sulpher 4
Pot. Nitrate 4

( I wore gloves, and a good mask and goggles... I have been putting off working with lead, but find bismouth really hard to get)

I mixed well using diaper method. i then dampened with NC laquer and pushed through 10 mesh screen into a bp prime and let dry for 48 hours. On trying a couple of the granuals all i am getting is an orange glow, they don't seem to want to crack at all!

I have also screened for size and tried only what passes 10 mesh and stays on 20 mesh but still no luck!

Any thoughts or comments? Should i have dried them longer? better prime? mixed better? This is my first batch so are these things tricky to get right?

jay

[Jimmymcknife]

...developing my hobbit!?

i meant hobby... although...

[Mumbles]

What size of magnalium did you use? What NC source did you use? Ping pong balls could do this if they're not really NC. It is also possible you didn't get enough NC in there, though that usually manifests itself in other ways.

I've never used that formula, though see it around here and there. You may want to try a different formula, without KNO3. I've heard a lot of people say it can kill the reaction, a lot like you describe. It makes the dragon eggs burn continuously, or could attack the metal. This being said, a lot of people use perchlorate primes.

Being as how that formula is so wide spread, I wonder if the problem came from dropping them into BP. Most of the time they're dried first. Perhaps the integration messed something up.

[pyrotechnist]

If NC is important how come phenolic resin is used in industry and works great? I just do not fully understand the NC role in dragon eggs.

[Jimmymcknife]

Hi Mumbles,

I used bought nc from cooperman, i have nothing but good things to say about his products.

Perhaps dropping them into bp was a problem... i have another small batch drying that i didn't prime so we'll see how they turn out. I mixed the nc in until the mix was pretty doughy and stuck together a bit after ricing (hence the bp to try and keep the grains seperate). Just noticed the cost of bismouth compared to lead and since i have a stash of lead i'd be keen to use it up (kinda get it out of the way and eventually replace it with some less nasty substitute). So if anyone has experience of lead eggs...?

Oh, the magnalium was 100 - 250 mesh, the formula asked for 60 - 200... maybe there weren't enough larger particles in my mix?

j

Edited by Jimmymcknife, 11 December 2010 - 01:11 PM.

[pyrotechnist]

Just a thought can polystyrene be used as a binder for dragon eggs? it dissolves in acetone easily enough to be used as a paste but never got round to trying it myself.

[Mumbles]

Have you heard that phenolic resin works, or have you experienced it? I'm just wondering as there are a lot of myths floating around in pyro. You can use dextrin too by the way. By lack of NC, I meant more a lack of confinement or consolidation, not that a certain amount is required for the effect. It seems that if the grains are too porus, the effect tends to suffer.

[Vic]

dampened with NC laquer and pushed through 10 mesh screen into a bp prime and let dry for 48 hours. On trying a couple of the granuals all i am getting is an orange glow,

At a guess I would say that pushing through a screen they are going to be to flaky you want nice hard chunks with plenty of NC in there.

With my experience with a very similar formula by larry stevens and I had great results, the difference in my method was that I rolled mine between two sheets of cling film and then peeled off the top film and then cut into small cubes 1/8 square or less. And then left to dry on the cling film once dry they are easy to remove and aren't stuck together, give that a try and see.

[cooperman435]

I was always under the impression that Nitrates lessened or ruined the dragons egg reaction?

I assure you also that using dextrin in replacement of NC doesn't work as a straight swap, based on my (limited) knowledge of the specific dynamics taking place I'm of the understanding that there are two seperate reactions when they burn, one is where the fuel (nc, dextrin etc etc) burns creating heat which leaves hot metal and Oxides which then react violently as a thermite to create the pop. Nitrates hinder this reaction as I know that priming with BP can lead to leaching of Nitrate and stop them working

Please correct me if wrong

[pyrotechnist]

I assume dragon eggs where a chinese invention in which case I would assume the original idea was to create some sort of star that was water proof in which case this is where NC comes into into play and was merely a binder for the effect so that it could be used in water bound stars etc. It would be interesting to see what other plastic type substances can be used in its place as a binder and some sort of crust forming layer? Could it be that the binder also plays a role in forming a slaggy layer that entraps the internal reaction causing the explosion which would make sense to an extent.

[a_bab]

NC helps the reaction by allowing the "egg" to pass the first reaction faster (the melting phase) as it spreads the flame and combusts itself.

Other binder may work, but I feel it's like playing with a strobe or glitter compo: too much of something and it won't work anymore.

[pyrotechnist]

We really need someone to do a full study on dragon eggs to find the actual reaction that occurs as it seems there is mixed theory on what happens and no solid research unlike with glitter where we know much more about it. To what mumbles has said people have got a successful result using dextrin which is interesting though I am sure a lot of dextrin may be required.

[Mumbles]

According to this post on rec.pyro dragon eggs can be too small, which may also be your problem. I guess it makes sense. There is a smoulder, and flash phase. If you can't get the star hot enough, it can't transition.

http://groups.google... lloyd NC whisk

I could have sworn there was a study in pyrotechnica about dragon eggs, similar to the ones on glitter. Even the glitter mystery isn't fully solved, though we have a much understanding. It seems there is only a report on alternate metal oxides to move away from lead. There may be some information in Oglesby's book. I'll have a look around, but I just have a feeling there is a more complex study on dragon eggs somewhere.

[Jimmymcknife]

Thanks vic, i'll try disolving the eggs and cutting them a bit bigger, i guess if a temperature has to be reached during the smoulder phase then my eggs could well be a bit small... Cooperman, do you have any more info on how/why nitrate potentially ruin the effect? I have a feeling i'm starting out on an obsession here, Mumbles if you do lay hand to the study that you think might exist i'd be really keen to read...

thanks for all the help so far!

[cooperman435]

I cant say why no lol, and Ill be honest it comes from some time ago and a thread long gone bye.

Ive tried a lot of formulas and played with them somewhat to try get one to work well in a dextrin bound comp, the best I came up with (which I think is very good) was :

(Altered from) David Trimmels, Bismuth Dragon Eggs

Bismuth Trioxide :37.5%
Copper Oxide (Black): 37.5%
Magnalium 400#: 25%
Dextrin: +5%

Weighed, mixed and then wet with 1/3 meths to water, granulated and allowed to dry totally before priming ( I cant remember what I last used but it needs to be hot and I recall avoiding Nitrates unless using red gum as the binder for the prime with acetone).

Please comment :-)