PyroGnome Posted June 19 Posted June 19 Back on the asphaultum track I decided to look around to try to find historical compositions before messing with perchlorates or chlorates so I could get a better idea of range. It turns out (from Encyclopedia of Explosives and a couple of web sources) that a KClO4 / Gilsonite (75/25) blend was used in the first solid rocket-assist short takeoff (RATO) boosters for jets, and was possibly the first solid fuel rocket used for anything meaningful. Apparently it works extremely well as a rocket fuel due to the energy density, which might make it a useful material for smoke-trailing daytime rocket effects and oddball things such as dark smoking serpents / tourbillions / hummers which I've not seen done before as well. I'm sure the data on how the GALCIT boosters were loaded is floating around in some old declassified military document that I didn't seek out because I wasn't looking for it. I'm going to test out perchlorate / gilsonite at somewhere around 55/45 and work around that range. I don't think chlorate will be necessary. The wikipedia JATO article has some pictures of takeoffs with various solid booster rockets and a couple have smoke trails similar to what I saw when burning gilsonite with a good oxidizer ratio with KNO3, but they don't mention exactly what booster was used for the photos. Unexpectedly (I wasn't looking for it) I found an old jpyro glitter article from someone who had experimented with all sorts of odd compounds during the 70s and was able to use 3,5-dinitrobenzoic acid as an auxiliary fuel in a sulfur / antimony sulfide - free KNO3 oxidized glitter formulation he found quite effective along with various salts of it although that's a bit off topic.
PyroGnome Posted August 12 Posted August 12 On 5/22/2025 at 4:39 PM, Mumbles said: This is just for informational purposes, not a suggestion, but potassium picrate based whistles make a dark to black smoke when they burn. Oxygen containing molecules are not always the enemy for dirty burning. There may be something different about how salts decompose vs. the free acid, but then again Na/K benzoate/salicylate whistles have a fairly white smoke trail. Also not a suggestion, although the price should keep people away: Picric acid also produces a black smoke when it completely detonates according to encyclopedia of explosives and related items, but an orange smoke on incomplete detn. This was used to easily identify which had happened during testing. I believe this was mentioned for ammonium picrate as well. I found this fairly interesting as most such equations lean towards producing nothing but invisible gases. So maybe it's possible terepthalic acid or khp could produce black smoke in an oxygen-poor environment (lots of aluminum powder, very little oxidizer) like @JAWChemist encountered. Magnalium or magnesium would probably sustain combustion better but might need an auxiliary chlorine donor to get rid of some of the white MgO "smoke" and shift it away from gray. The same source also suggests that K. picrate is insensitive to friction and not particularly impact sensitive (less than most flash powders anyway which isn't exactly a fantastic seal of approval but it's probably safer than something like strobe rocket mix). Apparently the major issue with it is that igniting it in open air causes it to explode (not detonate) while adding KNO3 can reduce or eliminate this tendency but massively increases friction and impact sensitivity, so you're damned if you do and damned if you don't. Hardt states that in fireworks KNO3 was primarily added when the black smoke was undesirable since it can cut down or eliminate it and mentions semi-forgotten (as of then) daytime black smoke whistle shells using pure potassium picrate which I'm sure were amazing looking. I'd not seen the mention of the pure compound being used as a whistle elsewhere. I'd love to see one but not make it. The same effect could be done more safely with KHP whistle pressed halfway (it's the lowest-smoke mix in my experience at least although any could be tuned) followed by a solid clay plug and whatever decently fast burning colored smokes mix venting through holes at the front end and ignited by a piece of match on that side. A pretty cool looking rainbow of darting smokes could be done that way, or use a serpent / tourbillion made similarly if you don't want the noise. Anyway Hardt says that the K. chlorate / gallic acid mix that largely replaced these for a short time was far more dangerous than either, but at the time it was more an issue of nobody wanting to work with potassium picrate because aside from being a strong yellow dye and irritant to whatever skin it touches, a single grain of dust is horrifyingly bitter. People were willing to risk the far less safe mixture to avoid working with the nasty stuff. Oddly (I guess, I shouldn't be surprised by anything anymore) aldrich will still sell me and presumably anybody picric acid shipped in water but it's very expensive, with a 6 month lead time on 500g quantities, so you'd better make the $200 for a single chemical in a black smoke whistle shell worth it if you're willing to pay. It's veering off topic again (I'm good at that) but there are some black smokes buried in the insane patent fittingly filed by someone named Jack De Mente back in 1951 which involved fittingly crazy mixtures of halogenated compounds of heavy metals and radioisotopes, iodates, bromates, etc to generate varying colors of smoke for signalling or chemical warfare. They're all sort of mixed together so I'd suggest avoiding it like the plague unless you know exactly what you're doing, especially if you read in detail and note that the inventor took the time to smell smokes produced from mixtures of things like unknown fluorinated compounds and smokes from selenium, tellurium, uranium, osmium... some of which were made from radioisotopes. Most of the materials are too expensive to be reasonable anyway but it's an amusing read https://patents.google.com/patent/US2995526A/en
PyroGnome Posted August 13 Posted August 13 FYI I don't know how I missed this on my first read-through since I'm very interested in smoke / daytime shells, but in FAST Shimizu says the anthracene / perchlorate comps require stupidly high ignition temperatures, that they may have half the anthracene replaced with napthalene (most of the ratios I've seen imply all of it can be replaced but maybe not in the same use cases) since anthracene was apparently always expensive, and that the black dragon comp (56 / 33 / 11, KP / anthracene / sulfur) is pressed into a tin tube with an igniting star on top and black match (thin walled cardboard well-sealed with thin aluminum foil tape to keep the napthalene in maybe?), while the black willow comp with a binder is cut without the coating of gypsum mentioned for the yellow and white smokes mentioned and then primed with silver wave, then chrysanthemum 8, then 6, then BP. Probably any hot prime would work in place of silver wave which isn't too far from a glitter as far as the comp goes, and since phenolic resin is one of the only things napthalene won't eat through it could probably be used to bind the step primes for a perchlorate version of the pure napthalene black smoke stars... by the time you've rolled the thing nearly round with all those prime layers the chances of napthalene seeping out to any reasonable degree at sane temperatures is next to nil, and there's a somewhat higher safety margin with a perchlorate version as far as how crazy an explosion the leftovers will produce if it does. Since the .uk link is down, here's web.archive of it https://web.archive.org/web/20180827132102/http://www.thegreenman.me.uk/pfp/smoke.html#Black The shimizu black dragon and black willow comp are the last two in the table. Asphaultum may make a good binder for napthalene stars, they're both soluble in the same things and the glacially high viscosity of asphault might trap any napthalene that decides it wants to escape for the forseeable future. My napthalene that's been sitting in the original bags (which look like BoPET) doesn't seem to have disintegrated from original mothball form or sublimed appreciably onto the sides of the bags while stored at ~66F for a year so I wonder how big of a deal the effect actually is at normal temps. A formula in my old database from who knows where (mostly old AFNs and PGI bulletins from the 90s) replaced the antimony sulfide in one of the black chlorate / napthalene binderless smokes with airfloat charcoal, which will still produce an unintended effect if it goes off but the ratios work out so you'd be left with exactly H3 if all the napthalene sublimed. It was just 45/40/15 chlorate/napthalene/charcoal if that If the stuff was in tubes ala saettines with a very short delay layer and some foil tape on them, the worst you'd get from it going wrong would be a small ring of medium volume pops as they burst instead of trailing smoke and you can always just cough and pretend like you intended that to happen. 😉 On 2/28/2018 at 8:24 PM, MadMat said: I have read that the movie industry uses naphthalene for for the huge orange fireballs that always accompany explosions in movies. I once tried making a cremora with granulated naphthalene mothballs, but I made some serious errors in the construction and it was very underwhelming (It was very early in my pyro days and mistakes are bound to happen.). I never tried another one simply because I didn't have any more naphthalene... until now. Once the weather becomes more hospitable for pyro work, I plan on trying it again. I forgot to reply to this earlier. I never worked in the movie industry, but back in the 90s I got ahold of a large bag (30lb or more I think was the minimum quantity packaging) of a material called ChemFX or some similar spelling that was supposedly being used heavily for this. It was some treated wood meal / sawdust product that was made to completely combust easily when dispersed but burn slow enough that you didn't need to worry about getting unwanted fuel-air effects from it. Basically an easy to deal with version of the cremora fireballs everybody started making. The worst you could mess it up was getting it too wet and you'd just end up with a bunch of damp warm sawdust laying around. Well, I'm sure somebody could manage worse. It was pretty much impossible to find a ratio of BP to the stuff that didn't burn all of it up as long as you got it in the air so you could tune the fireball size and shape by a lot. If you wanted flaming debris shooting off, just spritz a couple of spots on the pile with a spray bottle full of water and it'd stick together enough there to throw a fireball off to the side that would just break up if it actually hit something. Cremora fireballs didn't quite hang in the air as long as this stuff, it looked a lot more like lampari or the crazy propane / white gas fire cannons some of my fire performer friends made. I have no idea how or why I ended up with it and it wasn't the cheapest thing on earth but it was something being sold to the effects industry at the time, apparently. As I understood it in the past they used white gas / naptha or straight gasoline when that's really all white gas was, potentially mixed with something slower burning like kerosene to change the duration of the fireballs. That's a limited understanding though. I know when I did fire dancing we all used coleman's fuel / white gas since it was pretty safe to work with as flammable liquids on saturated wicks swinging around your body go. I kinda doubt napthalene was ever used outside of small effects, you'd need too much heat to get it volatilized and it'd be very uncontrollable once it all went vapor on you at once, although it'll dissolve in hydrocarbons so it's possible it was an alternate additive to get big clouds of smoke. That russian patent I posted earlier using anthracite coal for black smoke salutes was meant for movie effects but was an artillery strike simulator so wouldn't produce the same type of effect. FYI to anybody following the saga of me waffling over alternatives, It turns out the procedure for measuring volatiles in anthracite coal is actually something doable at home... I'd have to look it up again but it involved weighing out a small amount of the crushed up coal, heating it to 900 in a platinum crucible (they didn't have the nitride / carbide ceramics or some of the weirder alloys back then so something cheaper could probably be used, platinum isn't that cheap yet) for 5 minutes or so, then taking the weight difference to calculate volatile percentage. Dead simple as long as you have something that'll take the heat. This makes that route more attractive since nobody seems to want to publish their coal's data but it's cheap enough to spend the $11 / 45lb on to see if it's in the right range and adjust procedure as needed. I just need to track down the right type of crucible that will take the temps and not do something stupid with carbon in it and probably pick up a cheap oxy-mapp torch since I doubt that temperature is in F. The procedure is under coal in the encyclopedia of explosives and related items (vol 3 maybe?) which I've been finding out documents about twice as much useful information on "related items" as it does on explosives (which are more interesting from a "dear lord why did they make this" point of view which you'll get about once every 2-3 pages or more often depending on what letter you're under).
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