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Cheapest dragon eggs


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#1 NeighborJ

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Posted 13 February 2020 - 11:37 AM

I've recently been experimenting with some unconventional crackle formulas. Ned Gorski had a topic on his site which sent me down this path.

The goal is to make a functional dragon egg formula using the least expensive chems. Bismuth trioxide being the most costly of the chems followed by N/C. These chems arent prohibitively costly but over the coarse of time or as batches get larger it will add up. The formula I have settled on eliminates both of these chems.

66: black copper oxide, 30 (200-325) mesh MgAl, 4 dextrin.

I found it necessary to prime them with a strobe igniter prime (Bleser #28 strobe igniter prime) followed by a thin layer of BP to ensure it all takes fire immediately. The prime was applied in a star roller with plain water in a spritzing bottle.

The eggs theirselves were made by adding a 1% dichromate solution of water to the comp until the concentration reached 10% of the comps weight. The moisture was distributed throughout the comp evenly then tamped down in the mixing bowl to make a consolidated puck. It was granulated twice thru a 8 mesh screen and loaded into the star roller. The comp was allowed to spin for 5 minutes until the grains rounded off and formed small stars. I sifted the stars thru the 8 mesh screen to locate the larger stars, they got regranulated once again and loaded back into the roller with all the others. Once I was satisfied all the stars were round and would pass an 8 mesh, I started rolling the prime.

Drying the stars only took a few hours in the heated drying box. A few stars still showed signs of moisture at the time of testing so I'd recommend additional time in the drier if you have it.



I included this detailed record because I've only made this one batch. If someone else has different results then we can come back to this post to review any differences in the process.

Neighborj

Edited by NeighborJ, 13 February 2020 - 11:40 AM.

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#2 memo

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Posted 13 February 2020 - 01:59 PM

looking good NJ. just got back from panama on a 2 month break and my shop is stored in a 20 foot container. i need to get it unloaded  so i can start building again. im going to give that a try. thanks for the notes and work


Edited by memo, 13 February 2020 - 02:00 PM.

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#3 Yus

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Posted 13 February 2020 - 02:41 PM

NeighborJ, crackling composition investigation has a long story and takes part over few decades. First chinese, and further japanese studied different crackling compositions and some results were published or patented more than 20-25 year ago. The CuO - AlMg system always gives quiet noise/crack and it is hard to ignite. Only playing with preparation this composite can be improved, for example, make nano layer structure; but it is impossible to do at home. Addition to CuO - AlMg other transition metal oxides or low melted salts (nitrates) improve ignition properties, but to increase loudness only Pb and Bi oxides should be added.



#4 NeighborJ

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Posted 13 February 2020 - 03:10 PM

I am in agreement with you there. The bismuth crackle is a bit louder but not by much, the goal was inexpensive and functional.

The Bleser #28 strobe igniter was the first prime I tried which can reliably ignite them, perigrin MgAl inner prime may also work but I haven't tried it. I hadn't a reason to explore the priming of them any further.

The tiny ammount of dichromate in the comp does serve as the low temp oxidizer and facilitates a brief smolder between prime and report. It does nothing to increase the volume of the report. Without the potassium dichromate solution the eggs still pop but there is no smolder between prime and report.

This and like formulas can open up options to people who may not have easy access to bismuth trioxide, red lead, potassium dichromate or nitrocellulose.

Edited by NeighborJ, 13 February 2020 - 03:56 PM.


#5 Yus

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Posted 13 February 2020 - 04:58 PM

Ok. You can try one more cheap: CuO - 65%, Ba(NO3)2 - 10%, AlMg - 25%, Red Gum - 3%.

Its 1 mm dia granules work good in fountain (see 0:42)

 



#6 Dylman

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Posted 13 February 2020 - 05:17 PM

Yus, are those mixed into a fountain compositions? If so which composition. Thanks. Dyl

Edited by Dylman, 13 February 2020 - 05:19 PM.


#7 NeighborJ

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Posted 13 February 2020 - 09:05 PM

Thanks Yus, I'll give that formula a try.

#8 kingkama

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Posted 14 February 2020 - 07:05 AM

Composition is binded with NC or dextrine or Phenolic?

#9 NeighborJ

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Posted 14 February 2020 - 08:02 AM

The one I posted at the top is dextrin bound for ease of rolling. The one Yus posted apparently is redgum bound, I'd say alcohol would be the best solvent for rolling those. I'm not a fan of rolling stars which don't use water solvent but I'll do it for a test.
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#10 NeighborJ

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Posted 16 February 2020 - 10:26 PM

I'm planning to try the formula Yus has posted above tomorrow. After comparing the cost of the two formulas I found that they are almost identical in cost. The Dextrin bound formula being $9.97 per lb and the RG bound formula $9.82 per lb. This did not take into account the cost of solvents which would ofcourse tip the best value towards the dextrin bound comp.

I'm collecting batches of all formulas tested and will post a comparison video and evaluate their performance.

Edited by NeighborJ, 16 February 2020 - 10:27 PM.

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#11 NeighborJ

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Posted 18 February 2020 - 02:39 PM


This is my latest test. Still haven't tried Yus formula yet but at this point I see no need. Using the red copper oxide blended with the black copper oxide gives almost identical results and for only $6.17 lb to make.




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