Prechain Posted November 6 Posted November 6 Ive been looking around quite a bit and i couldnt seem to find out how to make these "time rain" stars but does anybody know a formula i will provide a video below for reference thanks
Zumber Posted November 6 Posted November 6 It is crackling willow effect. Either pumped or rolled matrix stars with charcoal tail mixture. If you are very new then don't attempt just stick to Black powder effects first. Crackling is not for beginners.
Prechain Posted November 13 Author Posted November 13 also have a question ive done rockets like bp, sugar, whistle and strobe etc but im completely new to shells what size should i start with and are there anything of concern that i should know?
PyroGnome Posted November 13 Posted November 13 I started with 3" back in the day and mostly made those up to 4-break, but I'd recommend starting with 4". Getting the break hard enough for good spread on 3" cylinder shells is a pain and you're limited on the types of inserts you can use if that's your thing. Round shells are fun too if you don't mind building a star roller (which is pretty easy / cheap) or buying a star plate. The shape doesn't lend itself to evenly filling with cut stars to get a nice round burst. If you've made strobe rockets consistently those crackling microstars (pretty sure time rain is just matrix comets with those embedded, which necessarily makes the shells fairly large) aren't anything to worry about. I've also seen the time rain label on what usually gets called a "dragon flower" though, which is when the stars snap at the end with a large burst of titanium sparks scattered in a circle. That's what I'm going for. Roughly the same precautions as strobe; they're friction and impact sensitive, but less chemical compatibility issues apply (thanks to the lack of ammonium perchlorate and use of MgAl). The formulas are high energy thermites, technically, with a very large melting point difference between the two oxides and the the two metals in the alloy that are responsible for a mostly one-pop strobe effect. The old and supposedly less difficult to get working formulas were lead tetraoxide / CuO / MgAl / Dark Al bound with NC, which is what I tried a couple of weeks ago with zero luck whatsoever... they start the dark phase reaction but the flash phase makes less sound than MgAl glitter. So last night I rolled up 100g of a high CuO / Bismuth Trioxide / MgAl version bound with phenolic resin with isopropanol solvent (protip: rolling 100g batches of stars is massively more difficult than rolling 1lb batches but if you can do it large batches will seem easy) and took one of the smaller ones (~1mm) outside and lit it with a blowtorch and it went through the dark phase then went off like a firecracker, impressively loud considering how much of it was a mustard seed core. I can go look at the formula I used if you want it. Most of the the bismuth ones call for NC as well but I didn't want to use it again because I'm apparently sensitive to nitro compounds (making them the only chemical that bothers me, I can stand around in clouds of acetone or HCl gas for hours) and it gives me an instant massive headache. The phenolic formula used ~2% resin and they rolled up nice and round so I'll save the NC for when I make some strobe rockets where it seems more necessary. 🙂 Bismuth trioxide isn't particularly toxic, red lead is toxic if you ingest it (which is the most avoidable thing on the planet, you'd have to be trying) and probably not good to inhale smoke from while testing on the ground. I might try making another small lead tetroxide based batch bound with phenolic resin and with the higher CuO ratio and lack of added aluminum like the bismuth formula I used to see if I get better results. Bismuth has a melting point ~100F lower than lead which should give a more even ignition from the "flower" comp that's getting rolled over them so I suspect it'll work better but it's always worth trying. The rest of the lead tetroxide is getting used as an oil paint pigment.
Prechain Posted November 13 Author Posted November 13 Thanks for the advice. I've been really interested in the 'dragon flower' effect, but I’ve never been able to wrap my head around microstars and comets. I haven't done much research yet, but they don’t sound like something for beginners. However, I always enjoy a challenge. I’d like to know if there are any effects I should start with. I’ve been really interested in brocade and willow, and I don’t think they’re too hard based on what I’ve heard, but I’m unsure when I should start experimenting with microstars.
PyroGnome Posted 3 hours ago Posted 3 hours ago Microstars aren't particularly hard to make, just different formulas than regular stars. Shimizu published some, there's a really high quality chinese blue floating around if you search, etc. One of the nice things is that you can make enough for years without spending too much and press them into all kinds of things. Gerbs / fountains (tons of safe & sane stuff uses them), delay comp on rockets if they're small enough not to clog the nozzle, comets, etc. I tested one of the largest ones from my batch along with a small one after they dried... probably 8mm. From 15 feet back it got my ears ringing like firing a .308 without earplugs. Here it is for posterity (I have lots of MgAl sizes for glitters and strobes already so it worked out, you'll probably want to experiment). The standard formulas list -200 mesh usually but this one originally listed -100: 39.22% - CuO (black copper oxide) 29.41% - Bismuth (III) Oxide 15.00% - Mg/Al (80-200 mesh) 10.00% - Mg/Al (200-325 mesh) 4.41% - Mg/Al (-325 mesh) 1.96% - Phenolic Resin Add isopropyl alcohol to make a clay and sieve over a star roller, cut, or roll on mustard seed (or without cores since it tends to aggregate on the largest pieces of Mg/Al and form stars from there either way, I don't think it would be too much more difficult. Go fairly light on the alcohol either way, since so little binder is needed due to the density it's easy to overwet. They'll still dry very solid.
johnnypyro Posted 2 hours ago Posted 2 hours ago A really simple but effective composition with this type of time rain effect is Tiger Tail (or C6, C8, etc.) with 10-15% #20-60 MgAl.
Zumber Posted 1 hour ago Posted 1 hour ago 42 minutes ago, johnnypyro said: A really simple but effective composition with this type of time rain effect is Tiger Tail (or C6, C8, etc.) with 10-15% #20-60 MgAl. A good way is to take black powder and start adding more charcoal in increments say 5/10/15/20/30 likewise plus metal like titanium to give nice effect. Another alternative is to pick up already tested formulations like brocade crown ,slow gold or willow.
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