LardmanAttack Posted October 7, 2020 Posted October 7, 2020 Does anyone know specifically why Acetates (Calcium, sodium, strontium, barium) aren't really used in pyrotechnics? I've been doing some experimentation lately with Acetates (calcium in particular), and have found that when mixed with chlorate and perchlorate, they can be quite energetic, I imagine they behave quite similarly to whistle mix (although i've yet to make whistle mix so I don't know for sure) And I was also curious if it was possible to use them as colourants so they could be part fuel and part colourant, I've been particularly curious about the sodium salt.
SharkWhisperer Posted October 7, 2020 Posted October 7, 2020 (edited) Please share more details of what you tried and what you learned with Ca and Na acetate (hereafter "CaAc" and "NaAc", et al, with KCLO3 and KCLO4. Most acetates I'm familiar with are highly water soluble; I wonder if associated hygroscopicity might limit their utility, similar to the use of NaNO3 with Mg in environmentally-sealed illuminating flares/signaling devices but rarely in amateur pyro? A quick PubChem search of CaAc shows it degrades at low temps (160C/320F) to CaCO3 (aka "chalk"; already used as yellow color enhancer or burn inhibitor) and acetone, the latter widely used as a solvent in pyro, but not sure how it would affect various comp burn effects, especially those bound with NC or Parlon. Don't recall seeing any comps that use acetone except for a solvent that is then evaporated off. How does it react with metals like Al or Mg? Also says it's very hygroscopic, which would likely impair usefulness in some instances. Quick search of NaAc says it's usually present in trihydrate crystals and is not only hygroscopic, but deliquescent--hygroscopicity's extreme sibling where a chem not only absorbs a lot of atmospheric water, but does so to the point that it dissolves into liquid. This would also impair utility in pyro. Ooh, in the PubChem Hazardous Substances database, it states that NaAc "In water, liberates 42.25% available acetic acid; it is bound compound of sodium acetate and acetic acid." That'd degrade your Mg in a hurry (and guessing MgAl). Both NaAc and CaAc have an acetic odor if not perfectly anhydrous and at least CaAc degrades at pretty low temps. So...acetates' current lack of widespread use in pyro (if any?) is probably primarily related to it's love affair with water, and potential for forming vinegar (acetic acid) that could react with pyro metals. And maybe even generate a little bit o flammable hydrogen gas in redox w/Mg, MgAl, and Al... Not much info available (quickly) on the strontium salt, but it seems expensive and is also probably hygroscopic. Strontium nitrate, already with mild hygroscopicity issues, is a very useful oxidizer and colorant that produces brilliant reds, so not really a substitute needed unless it was better some way. Still, am very curious what you observed in your testing. <edited to add Strontium acetate findings and tidy a bit> Edited October 7, 2020 by SharkWhisperer
LardmanAttack Posted October 7, 2020 Author Posted October 7, 2020 Please share more details of what you tried and what you learned with Ca and Na acetate (hereafter "CaAc" and "NaAc", et al, with KCLO3 and KCLO4. Most acetates I'm familiar with are highly water soluble; I wonder if associated hygroscopicity might limit their utility, similar to the use of NaNO3 with Mg in environmentally-sealed illuminating flares/signaling devices but rarely in amateur pyro? A quick PubChem search of CaAc shows it degrades at low temps (160C/320F) to CaCO3 (aka "chalk"; already used as yellow color enhancer or burn inhibitor) and acetone, the latter widely used as a solvent in pyro, but not sure how it would affect various comp burn effects, especially those bound with NC or Parlon. Don't recall seeing any comps that use acetone except for a solvent that is then evaporated off. How does it react with metals like Al or Mg? Also says it's very hygroscopic, which would likely impair usefulness in some instances. Quick search of NaAc says it's usually present in trihydrate crystals and is not only hygroscopic, but deliquescent--hygroscopicity's extreme sibling where a chem not only absorbs a lot of atmospheric water, but does so to the point that it dissolves into liquid. This would also impair utility in pyro. Ooh, in the PubChem Hazardous Substances database, it states that NaAc "In water, liberates 42.25% available acetic acid; it is bound compound of sodium acetate and acetic acid." That'd degrade your Mg in a hurry (and guessing MgAl). Both NaAc and CaAc have an acetic odor if not perfectly anhydrous and at least CaAc degrades at pretty low temps. So...acetates' current lack of widespread use in pyro (if any?) is probably primarily related to it's love affair with water, and potential for forming vinegar (acetic acid) that could react with pyro metals. And maybe even generate a little bit o flammable hydrogen gas in redox w/Mg, MgAl, and Al... Not much info available (quickly) on the strontium salt, but it seems expensive and is also probably hygroscopic. Strontium nitrate, already with mild hygroscopicity issues, is a very useful oxidizer and colorant that produces brilliant reds, so not really a substitute needed unless it was better some way. Still, am very curious what you observed in your testing. <edited to add Strontium acetate findings and tidy a bit>I really haven't done very extensive testing, just mixing with Potassium chlorate, and attempting to light, I also tried adding aluminum powder one time, and another iron oxide. It seemed to help the burn rate somewhat. In open air at STP without any confinement, both the sodium and calcium salts when mixed with chlorate in a 70/30 ratio burned very inadequately powderizing and better mixing the chemicals better helped, but not by much. But when confined in aluminum foil and heated, it burns much more rapidly and energetically, and when confined in aluminum foil, with a small amount of aluminum powder mixed in, and hit with a hammer, it produces a tremendous fireball, I would say I did no more than 60mg and it was comparable to a .22 blank. Looking back, the calcium salt was very much superior to the sodium and I believe that you were correct in the assumption that the water chemically bound to the trihydrate would ruin it. But I found that heating both salts to decomposition with a torch left a fair amount of carbon residue, so it likely doesn't just produce acetone, much less when mixed with an oxidizer. I'd highly recommend watching this video. It's the only video on acetate/chlorate compositions that I can find online and shows that yes, most of these compositions are actually quite energetic, but this video focused more on the energetics and explosive properties, And i'm mostly interested in the pyrotechnic properties.
SharkWhisperer Posted October 7, 2020 Posted October 7, 2020 (edited) I really hope I misinterpreted your hammer test. Please do not ever smack KClO3/Al mixtures with a hammer, with or without acetate addition--that's just unpredictably modified flash powder, and with KCLO3 is predictably expected to blow. Good way to lose fingers/vision. You mentioned perchlorate in your first post. A little safer than chlorate for metal/FP mixes... Those, too, really don't require a hammer smacking. Careful there, please. Watched the vid & yup, there was a reaction. I think I'm more impressed with standard FP 70/30 using the same "visually estimated" test quantities. Because you haven't posted much here yet, I wouldn't avoid discussing energetic compounds per se, but strongly recommend you expand your conversation topics beyond flash formulations and hammer tests, and risk others misunderstanding your intentions. and safety practices. There's a lot of well known chems that react much more energetically with your oxidizer(s) than the acetates in the vid, and hygroscopicity and potential acid generation are likely the reasons why we just don't use acetates in pyro. Edited October 7, 2020 by SharkWhisperer
Mumbles Posted October 7, 2020 Posted October 7, 2020 You can make pure sodium acetate. It does form a complex with acetic acid as well if the stoichiometry isn't right or is intentional. The latter is usually called sodium diacetate. It's what gives salt and vinegar chips part of their flavor actually. Pure sodium acetate is going to be basic. The combination of being basic, highly soluble, and very hygroscopic will limit it's usefulness in compositions containing metals, as this trifecta can lead to undesired reactions. Other salts may have some utility, but I'm not overly familiar with them. The one salt that hasn't really been mentioned is copper acetate. It may have some utility in niche effects like colored flames, but it's probably best to avoid it in most compositions. All the copper sources we use tend to be very insoluble. This is actually for a reason. Soluble copper salts are quite corrosive to the materials regularly used in pyrotechnic tools. It's also quite hygroscopic on it's own as well. There is definitely room for experimentation here, but you may not find a whole lot of great success. Acids with longer, fattier, chains tend to reduce the hygroscopic nature of the salts and reduce the solubility. This is why you see more use out of things like benzoates. There has been some work done with other things like oleates, etc. A lot of acids have been explored, and it's probably telling that not a lot have come into common use. Usually they're expensive, hard to obtain outside of synthesizing them yourself, and aren't really any better than their more common counterparts. Definitely keep us updated if you continue to experiment. None of this is to say there aren't hidden gems waiting to be discovered.
Arthur Posted October 7, 2020 Posted October 7, 2020 One of the first things to look at is price! All firework ingredients are usually cheap to keep the retail cost down. There will be something interesting out there (benzoates are reasonable new to pyro and very useful) But it may be hard to find the next useful ingredient. Long term stability alone and in a mixed comp are important.
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