TheGandalf Posted January 21, 2016 Posted January 21, 2016 Hello. I've heard a talk about KNO3 / MG Compositions degrade over longer periods of time. Can it really be true? And what will they mean for my 2" salute shell? Will it no longer be effective if it takes a long time before being fired? What can be done about the problem? // Morten / TheGandalf
lloyd Posted January 21, 2016 Posted January 21, 2016 Potassium nitrate/magnesium mixtures WILL deteriorate; rather quickly. In fact, they may 'deteriorate' at such a rate as to heat up to the point of self-ignition. I hope you're not storing them anywhere you want to keep. LLoyd
TheGandalf Posted January 21, 2016 Author Posted January 21, 2016 Hello. I have no more lying around. Can I do anything to solve the problem? //TheGandalf
TheGandalf Posted January 21, 2016 Author Posted January 21, 2016 Ehh. What's the comp. recipe for that? //TheGandalf
lloyd Posted January 21, 2016 Posted January 21, 2016 We don't have "recipes" in pyro, Gandalf. The formula is 50/50 by weight. LLoyd 1
lloyd Posted January 21, 2016 Posted January 21, 2016 I should have added that the strontium nitrate must be scrupulously dried, and protected before and after mixing, because it is usually hygroscopic. The Mg will deteriorate in the presence of moisture, rendering the mixture non-explosive with time. We use that in commercial stage "air bursts", which I'm sure you've seen many times. Lloyd
TheGandalf Posted January 21, 2016 Author Posted January 21, 2016 Alright.Super information ) - What about safety, is it safe enough to work with? //TheGandalf
lloyd Posted January 21, 2016 Posted January 21, 2016 It's safe enough that when supplied as "binary kits", technicians are allowed to mix it on-stage. Like any flash powder, it's subject to ignition by friction, impact, or static electricity sparks. But so was that KNO3/Mg mixture you had. Lloyd
TheGandalf Posted January 21, 2016 Author Posted January 21, 2016 Okay. Super! Now I'll go to bed with a smile on my face. I look forward to start again Good night //TheGandalf
lloyd Posted January 21, 2016 Posted January 21, 2016 Oh... and when I said "scrupulously dried", I mean hot-drying in a low humidity chamber (about 125F) trayed in shallow layers, and dried for several days. It should then be packaged in moisture-proof containers, and not exposed to humidity while mixing or after loading. Unless it's contained in a plastic bag liner inside, it cannot be effectively used in pasted shells, due to water intrusion from the pasting process. Plastic shells work OK. On stage, we use Saran film (true saran, not the 'brand') to bag it. LLoyd
schroedinger Posted January 21, 2016 Posted January 21, 2016 Lloyd don't you think that it would be better to use barium nitrate? E.g. this was popular in western european states an still gets some use. And even devices allready years old still function without problems.
lloyd Posted January 21, 2016 Posted January 21, 2016 Barium nitrate flash powder does last longer in storage, but isn't as energetic as strontium flash. That's why we use it commercially in airbursts. Lloyd
MrB Posted January 21, 2016 Posted January 21, 2016 @ Lloyd: Curiosity. Why do you go with Sr(NO3)2 / Mg rather then KNO3 / MgAl? I admit, i do treat my magnalium with linseed oil, just so i can sleep better, but it's supposedly not needed. I assume there is a reason, either safety, or performance. Also, i've been using it exclusively for the last year, in pasted cylinder shells, so it seams unaffected by both the moisture from pasting, and environmental moisture. MgAl is a lot less reactive then plain Mg, and both MgAl & KNO3 is cheaper then the counterparts in a strontium mix, so that's why i went this route... Now i just wanna know what made you guys go a different way. Safety concerns, for example, would bring the question, "what" safety concerns, the pro and con's, and so on... Anyway, just curious.B!
lloyd Posted January 21, 2016 Posted January 21, 2016 I admit, i do treat my magnalium with linseed oil, just so i can sleep better, but it's supposedly not needed. I assume there is a reason, either safety, or performance.-----------------KNO3 doesn't play well with either Mg OR aluminum. Your linseed oil coating works (for a while) because it "plastic coats" the particles. It won't last indefinitely on the shelf, unless you take the same cautions with the KNO3 as I suggested for the strontium nitrate. Instead of answering everything directly, let me ask a question. When's the last time you found Mg/Al as thin as -325 Mg flake, or as finely ground as blackhead aluminum? As to the 'extra cost' of strontium nitrate -- well, it works, it's safe, and it's not terribly expensive unless you're just a 'thump junkie'. In that case, you should be making salutes with 7:3 perc/aluminum. Lloyd
Seymour Posted January 22, 2016 Posted January 22, 2016 I assume that Strontium nitrate is used preferentially to KP because you don't want the more brisant, for lack of a better word, qualities that come with KP based flash? I get that for stage use, long term stability or cost are not so important because such small quantities are used, and not stored for so long, but Strontium nitrate and Mg are two chemicals I tend to largely avoid for reasons already discussed.
MrB Posted January 22, 2016 Posted January 22, 2016 (edited) Instead of answering everything directly, let me ask a question. When's the last time you found Mg/Al as thin as -325 Mg flake, or as finely ground as blackhead aluminum? As to the 'extra cost' of strontium nitrate -- well, it works, it's safe, and it's not terribly expensive unless you're just a 'thump junkie'. In that case, you should be making salutes with 7:3 perc/aluminum. Lloyd 1: Not entirely convinced it needs to be as fine as "traditional flash aluminum" and it should be available in most grades where you can get Mg. But, now that you ask.... Um, never? I make my own, so i haven't really investigated it that much, but you have a point. 2: While i'm not much of a thump junkie, i do like the occasional boom. My main issue is that i live in EU, where (per)chlorates have gone extinct. I have somewhat shy of 45 kilos of KClO4 now, which will have to last until they lift the ban, (probably never going to happen) or i start making my own. I use it pretty much exclusively for colors, and whistle. I switched to nitrate based flash to cut back on my perclorate use, just so that the time where i have no other options then to start producing it my self, would remain more... distant. I don't store things for years on end, legal reasons. A couple of months at most, when building up "inventory" for a larger shoot.B! Edited January 22, 2016 by MrB
TheGandalf Posted January 22, 2016 Author Posted January 22, 2016 I'm confused by this discussion. I just wanna keep my fingers
lloyd Posted January 22, 2016 Posted January 22, 2016 (edited) Gandalf,I'm not so worried of your fingers as your home, your shop, your magazine, and your criminal record. Strontium Nitrate mixed with magnesium will not normally react quickly enough to self-ignite. KNO3 and Mg can, and have many times. Both will deteriorate with time if some moisture is present, but the KNO3 (again) may react by catching flame. The strontium version will simply degrade until it no longer works (unless you actually get it WET). We use it commercially for just that reason. If you cannot get potassium perchlorate, this is among the safest flash powders you can make. KClO4/Al is the best, but I understand the EU has outlawed perc. Lloyd Edited January 22, 2016 by lloyd
TheGandalf Posted January 22, 2016 Author Posted January 22, 2016 I'd rather keep my fingers than my garage But I think I'll stick to Strontium nitrate / mg. Thank you Last year I had a 4 " with 280g KNO3 / mg lying around
schroedinger Posted January 23, 2016 Posted January 23, 2016 (edited) Something else i can just recommend is BaSO4/Mg flash. It gives of a green flash and a deep boom, quite different to the high pitch of kno3 or perc flashes (yes i know kno3 is not as high pitched as perc, but this a much deeper sound).Also BaSO4 isn't hygroscopic. The only downfall these have, is that they are expensive, mg cost more then Al and BaSO4 is about double price of perc. But if you want a deel boom try it. Edited January 23, 2016 by schroedinger
BlueComet24 Posted January 23, 2016 Posted January 23, 2016 Do you know if calcium sulfate works well? It's cheaper than barium sulfate (you can buy it as plaster) and I know it works for thermite reactions. I'm not sure if it would be reactive enough for a flash and I don't know about the safety of it. Just a thought.
schroedinger Posted January 23, 2016 Posted January 23, 2016 I heard that it does work, but i never tried it.
Wiley Posted January 24, 2016 Posted January 24, 2016 What about KNO3 flash with sulfur and dark Al? I've made lots of 2:1:1 over the years, and it has kept well for nearly a year. It was suggested that an additional 2% boric acid would help the mix's longevity. 15g will report strongly under light confinement, and if well-confined, gives a healthy boom.
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