BP issues

[Ipaced789]

Just getting started in the pyro field, i have made some BP that seems to work great for lifting. Getting a good 200ft lift on a 2 shell with around 10g of lift (around 20 mesh). But, when it is used as a break charge, it just poofs. Any suggestions?

[Arthur]

Firstly every new starter thinks their BP is HOT then it improves til it really is hot. Secondly Breaking a shell is done by powder against the confinement of pasted paper for either a ball shell or a cylinder shell, if the powder is slow nothing will make it burst a shell well, also if the pasting is weak the confinement is weak and the shell will break as a dump or horsetail regardless of the powder.

 

The accepted amateur ballistic test for powder is the baseball test -time a baseball from boom to thud when lofted from a 3" mortar with 15g of powder -should be 12+ seconds.

[SharkWhisperer]

Just getting started in the pyro field, i have made some BP that seems to work great for lifting. Getting a good 200ft lift on a 2 shell with around 10g of lift (around 20 mesh). But, when it is used as a break charge, it just poofs. Any suggestions?

When you're describing lift mass versus shell size, the critical parameter is the lift mass:shell mass (not diameter) ratio. A 2" shell filled with charcoal stars can weigh half of a 2" shell filled with dense Dragon Eggs or other dense materials.

 

It's also really easy to underestimate visual height estimations of shell bursts with smaller shells, especially if you don't have a lot of distance separation from the firing mortar. This is reinforced by many commercial 1.4g mortar/shell kits that state a given burst height/diameter but fail to meet those altitudes/diameters.

 

But it sounds likely that you also are having containment issues with your burst. And if your BP isn't quite as hot as you think it is, you can just keep dumping more in a mortar to get lift, but a shell has size constraints and burst powder limitations.

 

Providing more details on your BP manufacture/components (especially charcoal, milling or not, granulation, binder content) and your shell construction and mass/mortar length, shell/mortar fit, and launch-burst timing would be useful information for helping you sort out your issue. A pic of your starting device and a video of a launch/burst would be even more helpful.

 

Although the baseball test is a decent standard to evaluate BP, a lot of people shooting smaller 1.4g-like sized shells don't have 3" tubes, and a baseball dropping from 300 feet can do some damage. You can also do a golfball test in a smaller mortar, just make sure that the mortar fit is appropriate. You can also do this with an inert shell. With smaller shells/balls, start with lift mass at 10% of shell/ball mass. Even a 2" shell or golfball will hurt if you get bonked on the head. Make sure people/property are safely distanced. You'd want a decent stopwatch and a quick hand. The calculation to determine approximate height (in feet) derived from total flight time is: altitude = (t^2 x 32.2 ft/sec^2)/2 where t= time measured from launch-to-"thud". If you use metric units, just substitute 9.8 m/s^2 into the equation for the acceleration by gravity component.

[Ipaced789]

Thanks for the detailed reply! So heres what I got so far:

 

Im filling the shells with straight BP granules, no stars just to get an idea of just how large the burst is instead of guessing, as stated, with a star burst. The height is most definitely above 150ft, as the burst is taking place over my radio tower which is 175ft. But I can definitely do some more testing.

 

As far as ingredients go, Im using a ball mill; pre-milled nitrate, air float charcoal hardwood (I know, I just ordered some soft willow) and milled sulfur. I use 1% dextrin as binder. Mill runs for about 12 hours ( modified harbor freight rock tumble, getting about 85rpm using 5lb lead 1/2 media )

 

Im granulating using a kitchen strainer, so about 20 mesh.

 

The 2 shells weigh 110g when loaded. Using 15g of lift. Im using 2 plastic canister shells, I PVC cement them closed, let them dry. I then use reinforced tape around the shell to further capsulate. Thinking this was overkill, Ive also tried without the tape.

[Ipaced789]

Also, the mast is 2in ID hdpe 14in long. The shells come out to 1.95in with the fuse attached. Snug fit but loose enough to not stick. Fuse timing is 3.5 seconds from launch to boom. Using Japan time fuse, 3 seconds per in at 1.75in with a quarter in used for cross matching.

[Arthur]

A Gentle warning! There is a rule of thumb when guestimating the lift powder needed for a shell, BUT it's inaccurate for small inserts and for large shells.

 

However if you do tests with the size of tube that interests you then your lift determination will be right for that size!

[SharkWhisperer]

Thanks for the detailed reply! So heres what I got so far:

 

Im filling the shells with straight BP granules, no stars just to get an idea of just how large the burst is instead of guessing, as stated, with a star burst. The height is most definitely above 150ft, as the burst is taking place over my radio tower which is 175ft. But I can definitely do some more testing.

 

As far as ingredients go, Im using a ball mill; pre-milled nitrate, air float charcoal hardwood (I know, I just ordered some soft willow) and milled sulfur. I use 1% dextrin as binder. Mill runs for about 12 hours ( modified harbor freight rock tumble, getting about 85rpm using 5lb lead 1/2 media )

 

Im granulating using a kitchen strainer, so about 20 mesh.

 

The 2 shells weigh 110g when loaded. Using 15g of lift. Im using 2 plastic canister shells, I PVC cement them closed, let them dry. I then use reinforced tape around the shell to further capsulate. Thinking this was overkill, Ive also tried without the tape.

I would probably wait until you get your hotter charcoal/BP and try again. You'll be very surprised at the difference charcoal makes. Your milling sounds ok. Suggest letting your dough temper for a half hour or so in a plastic baggie or covered bucket to let the dextrin become fully hydrated/activated to prevent soft granules. No clumping issues after 12 hrs in that HF mill? Clumps don't mill. If so, dry out your charcoal & nitrate (charcoal can hold a hell of a lot of otherwise difficult-to-detect moisture).

 

Like Arthur suggested at the beginning, it sounds like the most likely culprits are slow powder and quite possibly poor containment--if you just blow the caps off and don't burst the canister, you'll get a poor burst. Scout around for container debris. Getting appropriate altitude but suspecting poor burst points to containment. Hard to judge burst quality without stars to show a pattern--it's not going to be loud and brilliant like a flash salute, but should be a pretty decent deep boom. That size BP salute could be ground tested if safely done.

 

Where are you getting willow charcoal from these days? USA?

[Ipaced789]

Thanks again, I will Defintly try again when the new charcoal comes in. Maybe Ill try a few more shells with the current way and strap the canisters even tighter to see if anything happens. Defintly not expecting a flash boom, but more than a poof would be nice lol.

 

And no issues with clumping, yet. Ive read through here about the charcoal and actually dehydrated it before I ever started!

 

As for the charcoal, I ordered it from fireworkscookbook its a little pricey ($12 a pound) so hopefully worth it, Im a bit to lazy to make my own

[Richtee]

And for busting the smaller shells, consider making some Benzolift. Or slow flash. It’s hard to get a good amount of burst with the effects you desire in smaller shells. Was for me anyway.

[SharkWhisperer]

Thanks again, I will Defintly try again when the new charcoal comes in. Maybe Ill try a few more shells with the current way and strap the canisters even tighter to see if anything happens. Defintly not expecting a flash boom, but more than a poof would be nice lol.

 

And no issues with clumping, yet. Ive read through here about the charcoal and actually dehydrated it before I ever started!

 

As for the charcoal, I ordered it from fireworkscookbook its a little pricey ($12 a pound) so hopefully worth it, Im a bit to lazy to make my own

Cool beans. Your ERC BP will be much much hotter than your generic hardwood charcoal. Generic's great for primes and charcoal stars and slow blackmatch but sucks for BP. You can make it serviceable enough to get the job done but why bother when options exist. Your new problem will probably be slowing down your BP for some applications. It's a lot easier to do that than to work with slow BP from the start. Like others have said, you probably will only realize how sluggish your BP is after you've made your first batch with ERC. I predict you'll be an instant convert. A lot of folks, maybe most, start out young mixing the good ol' 75/15/10 in a mortar and pestle and think they're onto something when they get it sizzling, but that's just being optimistic. Yes, a "poof" is just not enough.

 

Smart about drying your charcoal out. I do that and then store it airtight with some reusable silica packets (wrapped in a fold of paper towel so they don't turn black). Works well to prevent mill clumping.

 

Chris at Cookbook has some of the lowest prices around for pound quantities of many pyro chems, but he hasn't had the ERC in stock for that long yet. He ships pretty quickly and has always been reliable. His MgAl is about the cheapest available ($14/pound for any mesh he carries for a few years now) if you're not going in with others on large quantities. Prices everywhere are just going to go up with the ongoing shipping delays ($$$) from Asia, so stock up on imported chems soon if you have the spare funds and a good idea of what you might want to experiment with in the near future.

 

Richtee mentioned supplementing your crummy airfloat BP with some pretty hot chems (Benzolift or flash). Nothing wrong with eventually moving into more energetic formulations but I wouldn't use them as a bandaid for shitty BP. It's used in so many fireworking things that shitty BP will just be a constant thorn in your side. Ask Ron Moper who used Benzolift until he realized that the BP was the problem and learned to fix that problem. Simples!

[Richtee]

spare funds and a good idea of what you might want to experiment with in the near future.

 

Richtee mentioned supplementing your crummy airfloat BP with some pretty hot chems (Benzolift or flash). Nothing wrong with eventually moving into more energetic formulations but I wouldn't use them as a bandaid for shitty BP. It's used in so many fireworking things that shitty BP will just be a constant thorn in your side. Ask Ron Moper who used Benzolift until he realized that the BP was the problem and learned to fix that problem. Simples!

YEah- I din’t mean it as a bandaid. Good BP is very important. But just because of the volume available inside 2” or smaller shells it’s difficult to get a strong break with even good BP. At least that was what I found. And I had some solid BP going on. 10-12 grams-ish gave the baseball a nice ride.

[SharkWhisperer]

YEah- I din’t mean it as a bandaid. Good BP is very important. But just because of the volume available inside 2” or smaller shells it’s difficult to get a strong break with even good BP. At least that was what I found. And I had some solid BP going on. 10-12 grams-ish gave the baseball a nice ride.

OP---Richtee is correct. Smaller shells often benefit from a harder break than larger shells, because in a smaller shell there's a smaller burst:star ratio simply due to geometry.

 

Your new hotter BP will be easier to dial in than the hardwood charcoal BP, for sure.

 

But your hot BP will be a limited improvement if you're not 100% confident in your shell confinement that BP needs. That's why I suggested scouting around for blown canisters or doing a ground burst just to see if you're shattering your shell or just blowing off the endcap(s). You mentioned I think gluing two canisters together, I'd imagine end-to-end, and capping with PVC cement--this could be a weak point or a strong point depending on technique. Better to err on the side of more confinement while dialing things in so later you don't find that this easy-to-correct parameter was the cause of headaches. Again, your hotter BP will be easier to experiment with. You'll get it working properly.

 

RT, I know you didn't mean burst supplementation as a bandaid to shitty powder, but a lot of new folks tend to use it exactly that way to accommodate their kaka BP instead of fixing their BP. In larger shells too, where decent BP should be sufficient. But OP is working on improving his BP with hotter charcoal, which is great. Then he can decide if burst supplementation is needed or not.

 

OP, Many smaller 1.75" Chicom 1.4 shells have their burst enhanced with a splash of flash. If needed, a little goes a long way; too much brings other problems.

[Ipaced789]

New charcoal will be in today, so Im gonna mill it to airfloat then make some granules and rice hulls in a 5:1 mix to test. Will let you guys know!

 

As for hotter comps, Ive been making flash for years, the 7:3 kind, I just dont enjoy making it, no matter the precautions it scares the socks off me.

 

As for containment, Ive found the shells, and it did in fact just blow the lid off, which is weird. So what I had stated was, I pvc cement the lids on. These are 2 plastic canisters with plastic lids. I glue the lids with pvc cement, wrap with reinforced tape, then spike it. And somehow its still blowing the lid off rather than cracking the shell. Hopefully new powder will do the trick.

 

Can anyone tell me, with the 6lb HF tumbler and 5lbd lead media, what is the max all in one go amount of comp I can make? Ive been doing 120g batches, but would like to do an even 200 if it will not pose any additional issues.

[SharkWhisperer]

New charcoal will be in today, so Im gonna mill it to airfloat then make some granules and rice hulls in a 5:1 mix to test. Will let you guys know!

 

As for hotter comps, Ive been making flash for years, the 7:3 kind, I just dont enjoy making it, no matter the precautions it scares the socks off me.

 

As for containment, Ive found the shells, and it did in fact just blow the lid off, which is weird. So what I had stated was, I pvc cement the lids on. These are 2 plastic canisters with plastic lids. I glue the lids with pvc cement, wrap with reinforced tape, then spike it. And somehow its still blowing the lid off rather than cracking the shell. Hopefully new powder will do the trick.

 

Can anyone tell me, with the 6lb HF tumbler and 5lbd lead media, what is the max all in one go amount of comp I can make? Ive been doing 120g batches, but would like to do an even 200 if it will not pose any additional issues.

If you're blowing caps off with slow powder, you might do the same with hot powder, too. You need those caps on more solidly, for sure. "These are 2 plastic canisters with plastic lids". Are you gluing two canisters together or do you mean these are 2"-diameter plastic canisters??? Big difference and your wording suggests you're making shells with two separate canisters, which sounds odd, especially for preliminary. Guessing you mean plastic canisters for 2" mortars? Gotta be crystal clear in describing comps and device parameters to minimize reader misinterpretation, which can be dangerous with energetic comps/devices.

 

Clearly, your current containment approach needs improvement. Maybe it's just a matter of more tape strips holding the caps on. Or better cementing. Maybe glue an additional cardboard round cap under or over your plastic endcap before taping. Caps shouldn't just blow off and leave the canister intact. You'll be stuck with crummy star patterns with weak dispersion instead of good symmetric bursts.

 

I've used that same HF tumbler before. Many hobbyists start with something similar. Can only run one barrel with a half-jar of lead or the motor bogs down. Both jars if you underload them with media and just leave it running longer. You can efficiently mill around 175g of BP in those; any more is pushing it.

 

I've run 200g loads and at that point the efficiency begins to noticeably suffer and burn rate varies more from batch-to-batch. 200g isdefinitely overloaded, or very close to it, but you might get away with it with longer milling times. If BP quality varies across batches, they can be pooled and thoroughly mixed together before use or granulation. This gives a larger mass of powder with uniform burning characteristics. Til you get a bigger mill.

 

You've noticed that the fluffy charcoal settles in volume after it's been milled and incorporated with KNO₃ and sulfur, and settles into the media better. With fluffy charcoal, those little jars can be almost "full" when you turn them on and the volume is half that after milling.

[Ipaced789]

Sorry, I put the little quote symbol for inches but when it posts it goes away yes, I am meaning one single cylinder canister 2 inches in diameter, with a lid that is glued on. They sell them on pyrosource, just seemed easier to start with.

 

Ill work on the containment more for sure maybe the glue just isnt setting in the lip well enough, Ill have to see tonight/tomorrow for sure.

 

I will do no more than 175g batches then, thanks for the input!

And I figured as much on the charcoal

[LiamPyro]

When using a small HF mill, Ive found it helpful to pre-mill the charcoal alone before adding the other components. KNO3 and Sulfur grind down fast, but its the particle size of the charcoal that it is most crucial. To spice up the burst, regardless of how hot your BP is, slow nitrate flash or whistle are great in my experience. Personally, in the small shells that I make I use hot 5:1 coated rice hulls plus a booster - this is more efficient than filling shells with granulated BP in my opinion, as the total amount of chems needed per shell is much less even if it means using more expensive things such as perchlorate and metals. Good luck! Edited August 2, 2021 by LiamPyro

[Ipaced789]

Yeah thats what I started doing this weekend with the Willow I got in. The shells are finally breaking instead of just poofing. So definitely getting somewhere.

 

As for slow flash, is there any personal recommendations you have? All I have on hand is German and Indian black 2 and 4 micron al. Will this work, or will the surface be too much for slow flash. Obviously safety is always a concern, rather not dabble into mixtures that are extremely sensitive

[LiamPyro]

5/3/2 KNO3/Al/S works well in my experience, using dark aluminum. A couple grams thrown in with the BP rice hulls should do the trick! As for sensitivity, it would be hard to say, although there is at least a slight increase in safety over 70/30 simply because a nitrate flash such as this wont self confine in as small of a quantity. Edited August 2, 2021 by LiamPyro

[Ipaced789]

Awesome, will probably make a small batch tonight. Diaper or screen for this type?

[SharkWhisperer]

Yeah thats what I started doing this weekend with the Willow I got in. The shells are finally breaking instead of just poofing. So definitely getting somewhere.

 

As for slow flash, is there any personal recommendations you have? All I have on hand is German and Indian black 2 and 4 micron al. Will this work, or will the surface be too much for slow flash. Obviously safety is always a concern, rather not dabble into mixtures that are extremely sensitive

You keep mentioning willow charcoal. FWC doesn't sell willow charcoal. His fast charcoal is Eastern Red Cedar (ERC). https://www.fireworkscookbook.com/?s=charcoal&post_type=product Willow and ERC are both good, but different.

 

If you ever get tired of paying $12/pound plus shipping for ERC charcoal, you can buy the starting material for cheap here and make your own in an hour or two....https://www.walmart.com/ip/Pets-Pick-141L-Cedar-Bedding-Better-Absorption-5-cu-ft/40038084?athcpid=40038084&athpgid=athenaItemPage&athcgid=null&athznid=PWVUB&athieid=v0&athstid=CS004&athguid=46cd4115-007-17b0d42cad9cba&athancid=null&athena=true . They sell smaller bags than this 5 cubic foot bundle, too.

 

Please strive for accuracy when detailing the specific chemical components of energetic mixtures. This charcoal mix-up is pretty trivial but even small mistakes in defining mixtures and components can cause very real and sometimes explosive problems...

[Richtee]

Awesome, will probably make a small batch tonight. Diaper or screen for this type?

with nitrate- you can put it in a blender. NO..you can’t but shook about is fine. it’s pretty insensitive as far as explosives go.

[Ipaced789]

You are correct, it is cedar charcoal. I am not entirely sure why I intended on saying it was willow. Definitely understand the repercussions of inaccurate information.

 

As for making my own, Id absolutely love to give it a go soon, just need to finish the fire pit Im working on!