USAPyro's No-NC Dragon Eggs

[usapyro]

Not me. I think it's the formula. If it's SO sensitive to relatively-small variations in particle size, it's not a good, reliable one.

 

(sorry if this might offend... but I personally like "forgiving" formulae; most especially in a commercial environment where you can't constantly control employees manipulations of the materials.)

 

Lloyd

 

I think that the best formula currently out there are most likely the new heavy-metal free formulas recently published in AFN.

 

I'm not anti-NC anymore, after I figured out how to do it without the horrible "kneading".

[lloyd]

Do you know Ken and Richard? I do. Their crackles work, but are VERY sensitive to both the character of the materials and the finished particle size of the grains. If either is off, the stars just burn up or smoulder without popping.

 

Theirs is an experiment in how to make heavy metal-free crackie, but not an effort (yet) to be 'better' than the currently-accepted formulae. Richard is still doing a lot of heads-down research to try to understand the mechanism by which theirs crackles at all.

 

Lloyd

[usapyro]

Do you know Ken and Richard? I do. Their crackles work, but are VERY sensitive to both the character of the materials and the finished particle size of the grains. If either is off, the stars just burn up or smoulder without popping.

 

Theirs is an experiment in how to make heavy metal-free crackie, but not an effort (yet) to be 'better' than the currently-accepted formulae. Richard is still doing a lot of heads-down research to try to understand the mechanism by which theirs crackles at all.

 

Lloyd

 

Interesting... I was under the impression that anything published in AFN is a consistent proven formula.

[RichardH08]

Usapyro, I think you slightly misunderstand what Lloyd is saying. The published formulations are 'proven’ in the sense that they have been demonstrated to work, not just by us but also by a number of other people. However, I would be the first to accept that they are possibly less effective – and certainly more sensitive to the details of how the grains are formed and the way they are primed – than some of the more ‘traditional’ mixes.

 

In publishing our formulae, our intent was twofold; to demonstrate that some of the ingredients in previously existing compositions are not as crucial as many people think, and to encourage others to experiment along similar lines.

 

Our current research is aimed at seeing how far we can go in eliminating ‘essential’ ingredients and to see if the resulting, simplified formulations can offer any clues to the way that crackle works.

[Mia]

Usapyro, if you follow our work on Pyro-Gear and I doubt you do, to get the grains to go with a single crack you have to roll them, a solution of PVB or Phenolic is mist sprayed on to the granulated cores and rolled until spherical.

What Richard said is correct and also Lloyd for that matter, try the PVB colour formulations we submitted to AFN and bring back your results could be interesting regards Ken.

[usapyro]

Our current research is aimed at seeing how far we can go in eliminating ‘essential’ ingredients and to see if the resulting, simplified formulations can offer any clues to the way that crackle works.

I thought that was already understood? One metal of the MgAl alloy is initially consumed until the alloy ratio is shifted causing temperature increase and the reaction goes exponential

 

Or... Is there another mechanic underlying it? Perhaps the PVB is acting as some sort of "Flux" to de-alloy the hot MgAl? Well, that's the opposite of what flux does, but you get the point...

Edited July 18, 2017 by usapyro

[RichardH08]

I thought that was already understood?

That kind of explanation, originally put forward by Shimizu, sounds reasonable, but I've never seen any concrete data that indicates that it may be true. The evidence I'm gathering suggests that there is a fundamental flaw in the argument. It leads me to suspect that it is either wrong or, at the very least, that there is another mechanism that leads to the same result.

 

I'm sure that the presence or absence of PVB isn't the crucial factor, but I don't yet know what is. I did have an alternative hypothesis, but my latest measurements seem to have knocked that on the head.

[usapyro]

That kind of explanation, originally put forward by Shimizu, sounds reasonable, but I've never seen any concrete data that indicates that it may be true. The evidence I'm gathering suggests that there is a fundamental flaw in the argument. It leads me to suspect that it is either wrong or, at the very least, that there is another mechanism that leads to the same result.

 

I'm sure that the presence or absence of PVB isn't the crucial factor, but I don't yet know what is. I did have an alternative hypothesis, but my latest measurements seem to have knocked that on the head.

 

A hint may be that MgAl alone kinda crackles when burned in a black powder based glitter or similar comp. Anyone have an explanation for that?

 

Perhaps the dragon eggs composition just "synchronizes" what ever is occurring across all the particles of MgAl. If this is the case, there might be tons of different formulas possible.

Edited July 18, 2017 by usapyro

[lloyd]

I think I agree with that theory. The sulfur in BP contributes to the crackling Mg/Al effect, from what I've seen.

 

Lloyd

Edited July 18, 2017 by lloyd

[usapyro]

I think I agree with that theory. The sulfur in BP contributes to the crackling Mg/Al effect, from what I've seen.

 

Lloyd

 

This gave me a interesting idea... Even though Sulfur isn't heavy like Bismuth or Lead Tetraoxide. Maybe you could make dragon eggs with it and CuO by pressing the composition to a high density. Will definitely experiment with it and some other ideas this fall.

 

Really, the ultimate would be Heavy Metal-Free, and No-NC Dragon eggs! The only real downside of Bismuth Trioxide is it's so expensive!

Edited July 18, 2017 by usapyro

[lloyd]

USA,

I've made test batches of Mg/Al 'sparkling' stars (wouldn't actually call them 'crackling') with varying proportions of BP-type comps. I see delays in the sparkling, similar to what you see with conventional crackle, and they seem to vary with the sulfur content.

 

Lloyd

Edited July 18, 2017 by lloyd

[usapyro]

I have an interesting observation from my experiments with Bismuth Trioxide/CuO ratios. The higher you go in CuO, and the less Bismuth... The less "sharp" the sound. They end up more halfway between a *thumph* and a *bang*.

 

I'm not sure, but it could just be related to density of the comp...

 

Edit: Wait a minute... Al/CuO is a thermite. Are Al/Bismuth Trioxide and Al/Lead Tetraoxide also thermites? It's just a delayed thermite reaction then, hmmm... How to heat a thermite slowly to critical and syncronized in a comp without heavy metals.

Edited July 18, 2017 by usapyro

[Mumbles]

Yes, they all could be classified as a thermite, or Goldschmidt, reaction.

 

Also, even though it's essential for life in small quantities, copper is still a heavy metal.

[RichardH08]

copper is still a heavy metal.

Oh come, now! That may be true in an absolute sense, but it's really down to a matter of context. When talking about crackle, most people would interpret 'heavy metal' to refer to lead, bismuth and possibly a few others, such as tin and antimony. To an astronomer investigating the composition of a star, everything but hydrogen and helium is a heavy metal.

 

On a more serious note, one could speculate forever about the relative merits of magnalium, sulphur etc. and how they interact. It is clear that the principal source of energy is from reaction(s) of the thermite type. What isn't so obvious is why some combinations of metals and oxides exhibit the two-stage process that characterises crackle and others don't. A lot of research has been done on thermites, mainly in the form of nanocomposites. One result is that, even in the case of simple binary mixtures, the chemistry can be surprisingly complex. Just how relevant these findings are to understanding the crackle mechanism remains to be seen.

[Mumbles]

I was going off of the definition of a heavy metal. A dense, toxic metal. Copper toxicity is quite overlooked actually. Copper is reported in some places to actually 2-3x more toxic than lead though doesn't have the same stigma nor the known carcinogenic properties.

 

I could go about theories for oscillating reactions or compositions that burn "vibrationally" all day. One thing that has not been lost on me is that most of the good crackle metal compositions have 2 stable oxidation states. I've thought about them in a lot of similar ways to traditional AP/Sulfate/Mg strobes. The AP and metal burn to produce the dark phase, and when a critcal mass of heat or reagents build up, the sulfate and metal react to flash, then repeat. I've always wondered if a similar thing was happening in a dragon egg. Lead and copper oxides can both work on their own to some degree. The metal and oxide react to form reduced oxide (Cu2O or PbO for instance), then when a critical mass of heat or whatever built up the thing would explode in a more dramatic fashion. That doesn't really work for bismuth oxide, but then again I've never seen a good bismuth crackle without a mix of both it and copper oxide. I wouldn't be surprised to hear an all bismuth oxidized mixture works either though.

[RichardH08]

Fair enough. As you say, copper is reasonably dense, and certainly toxic in a sufficiently large dose. Part of the reason why lead has a worse reputation is that it isn't as easily eliminated from the body, so repeated small doses have a cumulative effect. My point was just that that, as far as crackle is concerned, I wouldn't interpret the term 'heavy-metal-free' to mean that there is no copper oxide present.

 

The idea that metals with more than one stable oxidation state are involved certainly has merit. It was part of Shimizu's original suggested mechanism and, while I don't buy the idea that preferential consumption of Mg causes the smoulder phase, partial reduction of the metal oxide can't be eliminated so easily. Unfortunately, as with many of the proposed mechanisms I've come across, it can't be the whole answer. About 4 years ago, when I first started getting interested in how crackle worked, I made a series of tests of approximately stoichiometric mixes with varying ratios of copper and bismuth oxides. They all worked to some degree or other, including the one that contained 88% Bi2O3 and 12% magnalium (plus 10% NC). A 2mm grain, when ignited with a blowtorch, produces a series of 8 to 10 sharp reports, with virtually no delay. It isn't the best of crackle compositions, but it does work.

[Mixer]

Even though the heading states No-NC Dragon Eggs - it looks to me that all the eggs made by USAPyro have NC in them.

Earlier in the posts it states;

 

"I have been binding the prime onto the eggs with a nitrocellulose spray (this contradicts the title) and at the rate that stuff dries I have had no problem with it. If done properly in a star roller making sure not to get things too moist I don't think there should be problems using ethanol either. But, have not tried it yet"

 

Further on in the posts - there is no mention at all that he actually did try it.

 

IIRC I tried this method a good while ago with poor results - also the granules were difficult to work with, and just crumbled when dry.

 

It seems to me that the *Optional: + 5g Red Gum - Binder (Alcohol) cannot work in this formula without the NC. (Unless someone knows different)

Edited February 1, 2019 by Mixer

[Yus]

I have found Richard Harrison's paper titled "Dragon’s Egg/Crackle Compositions" in www.pyrobin.com and marked as part 1.

Who knows the origin of this paper and where can I find second part? Thank you.

[Boophoenix]

Check Pyro-Gear. There are multiple threads on crackle and another with AFN links that may contain the document you are looking for.

[RichardH08]

I'm not sure I ever published a part 2. If I did, it would also have been about the effect of varying the proportions, but using Bi2O3 instead of Pb3O4.

 

The AFN articles are possibly more interesting and are available in the open section of the Pyro-Gear forum. There's no need to join up to see them.

[Yus]

I cannot

"You do not have the required permissions to view the files attached to this post"

Could you send me direct links in Messenger?

Thank you.

[Mia]

Due to new forum software you won’t be able to download unless you are a member and from what I see you are now.

[RichardH08]

The AFN articles ... are available in the open section of the Pyro-Gear forum. There's no need to join up to see them.

Apparently, that is no longer true. The new security measures mean that you have to join if you want to see any attachments.

[Yus]

He is going video with 1 mm cracking microstar rolled with 3% dextrine.

 

https://www.youtube.com/watch?v=feBfhd75jv8

[Mixer]

Dextrine does work (4%) but I find in all of my tests it isn`t as effective as NC because it quietens the crackle somewhat.

Edited March 2, 2019 by Mixer