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roger's pyrotechnic offerings and experiments


rogeryermaw

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it's ok with me. i like to see what people are working on.

 

glad you got the color worked out!

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I meant Bobosan regarding the boric acid.

With mgal the boric acid attacks the mg, so you did right as far as I know.

I did mill the comp (n1 btw, not d1), but it worked very well. Just tested, and I got the golden glitter I was looking for. It was beautiful indeed! Can't wait to see 110 of those in a 6".

I meant to film it, but managed to run straight into my car and dropped the phone, lol. Should've used a longer fuse..

It worked out anyways, vid of the 6 coming as soon as I shoot it. Meanwhile I'm thinking about posting my 4"—tests here if that's allright and of interest?

Coming in a couple of days Will be pumped Slow gold.

 

enan

 

The formula did not call for boric acid although it's common knowledge that nitrates will attack aluminum if your water percentage is too high. I roll mine and lightly spritz enough to gather comp and remain solid when dry. Have not experienced any adverse affects so far but like I mentioned above, I have some D1 made this past summer that I need to test. Perhaps this atomised spheroidal aluminum from Skylighter is pre-coated? I doubt it.

 

I did not mill any components other than the prilled KNO3, just passed them through 40 mesh before consolidation.

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I'm trying non-milled next time as well. My 16mm pumped stars burn way too quickly, and the 6" won't be a big flower. ALOT of short-lived glitter though!

 

I've rolled and cut nitrate/Al comps myself without boric acid too (didn't know about the danger at the time), and normally it's fine. But the day it's not, that's gonna be a big problem unless youre at a completely safe location... Be careful.

 

I mean to remember that you also rolled your D1 comps? Is it possible to roll using around 5-10% water? I'm using far more than that, but as you know, I'm not good at rolling..

Edited by enanthate
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The nitrate attack on aluminum doesn't really have as much to do with water content as it does with other factors. It's far more affected by aluminum particle shape, the basicity of the mix, and heat issues.

 

Flake is far more susceptible to attack due to it's high surface area. It also generally lacks an oxide layer. I've never used it in wetted compositions, but perhaps very fine atomized aluminum (say 10 microns or finer) may cause an issue as well for this reason.

 

The basicity is generally a result of the additives. Sodium bicarbonate has generally been fine for me. Barium, strontium, calcium, and magnesium carbonates are largely too insoluble to do anything. The one chemical that has caused me issues in the past is sodium oxalate. There are also reports of poor quality cryolite having issues as well. I suppose very high ash content charcoal may pose a minor issue as well.

 

The heat issues are from getting the composition too hot. Like most chemical reactions, this one speeds up the hotter the mixture gets. The reaction is also exothermic, so it's self-perpetuating. The heat issues can result from leaving a large mass of wet composition out. This may seem like a no brainer, but most people do wet their composition and let it temper. Occasionally things come up and your comp gets forgotten about. Also force heating to dry the stars may also pose issues.

 

For what it's worth, Mg and MgAl are also susceptible to this effect. Yes, boric acid will degrade Mg and seems to do the same to MgAl. You just have to be more careful with these compositions.

 

Largely this deleterious reaction is not an issue. I've been at this for the better part of 15 years, and I've only experienced approximately 2-3 issues. One was because I force dried a composition containing MgAl and sodium oxalate. At room temp it's fine. The stars actually worked fine, but they inflated like a balloon and had a large hollow core. Another was leaving a composition containing of sodium oxalate and flake aluminum wet in a pile in a covered container. Like I said, sometimes things come up. The final was from wetting comets containing MgAl with boric acid solution without thinking.

 

I usually don't bother with the boric acid under most circumstances. The only time I'll consider it from the onset is with compositions containing flake aluminum with either sodium bicarbonate or oxalate. Otherwise I want to experience a reaction first. If you start to notice the mixture heating up or smelling of hydrogen sulfide or ammonia, you can usually kill it quickly by spraying it with boric acid solution. I've saved at least one batch by doing this. The batch turned out just fine. You have to catch it early though.

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i have my share of failures too but they usually don't make the highlight reel. not everyone is interested in what won't work

 

However, by sharing your failures, you might save someone else time and chemicals. It would be nice to know sometimes if my "bright" ideas had already been proven otherwise. :P

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Thanks for explaining the reasons for these nitrate/Al reactions, Mumbles. I'll heed your advice should I use Al flake or any other chems mentioned in a comp.

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Good point Greg. Ok my failed attempts at d. eggs were on a couple of small test batches of about 10 grams each. First I tried a 90:10 red lead:80/200 mgal wet with nc lacquer, to a thick dough consistency and cut about 3 mm. I primed a few with kp/silicon and they took fire ok but no effect. Also tried the lead/copper oxide formula to no avail. Thought it may be the prime so I grabbed a few and roasted them with the torch but nothing. I suspect the lead but I'm not sure what's wrong here. What form of mgal is best here? Flake? Spherical or spheroid? Is the lead impure? I'd like to work this out but doubt I'll do it before NYE.
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I would try pcs are about half the size you refer to. I've also used a ratio of 89/11 using a flake Al not MgAl and in 200 mesh range. I went through a couple of pounds of red lead this year using this formula. My NC was the solids from Fire Fox. If you hit them with a torch and they didn't pop something is surely awry.

 

Mark

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4" slow gold, was quickly testing new homemade starplate without spacers, hence the very uneven size in stars.

Too bad the camera didn't get the bright golden color.

http://youtu.be/0xqW44U5MXM

 

Recommending booster any1? Couple grams of slowflash could help on the break..

Edited by enanthate
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3-5g of booster would be sufficient, maybe larger stars after you test some boosted shells.

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  • 2 weeks later...

 

my first try at a roman candle with some junk stars i had left over. 5 1/2 shots...i don't count the first shot. the tube above that star was too short to make enough pressure to send it high enough.

Edited by rogeryermaw
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I developed a new formula today. It may or may not have been done before. Before I reveal it, anyone care to make any guesses?

 

post-19283-0-06114800-1417049400_thumb.jpg

 

This was a 1.2 inch mine from about 100 feet away.

I meant to record video but had my camera set to take still pics.... sorry...

Edited by rogeryermaw
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no sir. i'e been reading a lot about compositions containing multiple colorants. just thought i'd give it a try.

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strontium nitrate and carbonate. phenolic resin/hexamine, red gum and potassium chlorate.

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i made a 10 gram test comp of these last night which behaved a little strangely. i couldn't get them to pop unless they were about 1/4" and then it was every bit as loud as a gram of well confined flash. today, i tried making a new batch and cut them 2-3 mm. this was the result.

 

15 g bismuth trioxide 37.5%

15 g black copper oxide 37.5%

10 g 100-200 mesh mgal 25%

n.c. binding + about 15%

Edited by rogeryermaw
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Happy to see that you're working on dragon eggs, I'm starting on that in a couple of days.

 

Have already tried a couple of different compositions, but no success. The best I made did make crackling, but they "exploded" in to several smaller pieces first, then crackled. So one egg would make 5-10 pops.

Got some 80-mesh MgAl couple of days ago, which hopefully will improve my next batch of DE's.

 

Have you tried this one?

Bismuth Trioxide 75

MgAl 200mesh 15

CuO Black 10

Al atomized 200mesh +5

 

 

Also, I'm looking for a formula to roll. Anybody done this before? Is it possible?

I can't roll with NC, has to be dextrin.

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Yeah, drop the MgAl particle size boys :) I blade mill my home made mgal specially for DE's. (Remotely)

What does that mean? You're using finer MgAl? Variation of sizes?

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Other way around mate, I have screened to expect 40-80mesh MgAl particles at around %85 then perhaps 80-120 around %20. They are extremely loud for 1mm eggs. Just mix the comp up well and get plenty of NC in there to bind 'em good.

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Those are good advices, will try that (specially the "lot of NC" part, I normally go easy on this). Cheers.

Got some 80 mesh MgAl, but dont know if its 50/50 or not. This might become a problem.

 

Btw, what comp are you using?

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Going easy on the NC tends to not yield as good of results. It seems counterintuitive, but I know a lot of people who actually overwet with NC. You basically make it into a thick soup and work it until it's the right consistency. From there you can granulate or cut or whatever you want. This does kind of preclude rolling them though.

 

After they dry out, you can screen them to size. Anything too large can be gently crushed, and anything too small can be reprocessed with just solvent.

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