How to improve the shell break?

[MinamotoKobayashi]

Making BP with the CIA method plus pucking and corning with an hydraulic presss and finally granulating it

make a very good and fast black powder, but if I compare the aperture of a commercial shell with one of my shells

I see that the commercial shells fling the stars much further away.

I state that I use a good system to bind the shells with gummed tape and I apply the right number of coils

keeping the shell shape rounded.

Some tutorials on Youtube show some guys putting the whistle mix powder on the centre of the shell before close it.

I have both potassium perchlorate and sodium benzoate to make whistle mix, but I'm really scared to use it.

I think this can made the shell very dangerous when I tap it with a rubber hammer to press well the internal granulated BP

or the coated rice hulls.

Or when unawares my shell fall from the table to the ground.

Or when I I roll the ball quickly into the floor while pressing it with the palm of my hand to make the pasted paper more evenly.

I do not want to lose hands, eyes and ears in an accidental ignition, especially when the shell is pasted and dried.

Can anyone suggest me a safe method to improve the shell break?

 

[NeighborJ]

Hi Richard, unfortunately there isn't much of a way to increase the burst strength of a BP shell without a booster. One can add more pasting layers but what usually happens is the stars will burn up in the burst leaving little left in their display.

 

The commercial shells use a heavy dose of boosters to achieve their burst intensity. If you desire to compete with them, a booster must be used. There is one possibility of increasing burst strength without burning up your stars from over confinement and that is to place a heavily confined maroon inside the center of the shell. This option is an outside the box idea but should give you the results your after at the expense of much extra work.

 

The whistle booster can be done in a mannor which would reduce chances of friction ignition simply by keeping it separated from the rest of the BP burst charge with a tissue paper flash bag. This flash bag method has several other benefits over the more common "dump in a pile of comp" method but most of them dont apply to the headers i assume you will be using them for.

 

 

 

Jason

[Mumbles]

Most chinese shells are overbroken and are not necessarily the ideal shells to be trying to replicate.

 

You'll never be able to get close to what they do without a booster though. If you want to try to up your power some without dealing with flash or whistle you can coat your burst with dark flake aluminum. This icreases the burning temperature and will result in somewhat higher casing pressures and larger bursts.

[MinamotoKobayashi]

Hello and thanks for the fast reply.

 

x Jason: "... heavily confined maroon inside the center of the shell" ... I do not understand what is "maroon"

 

x Mumbles: from Pyrogarage I have found "Aluminum German Dark", "Aluminum Pyro Dark", "Aluminum Super Dark" and "Aluminum Ultra". Which of these options could be better?

Must I coat the granulated BP? It seems a difficult operation ...

[Mumbles]

They're probably all about equivalent. Without more product info it's hard to make a deliberate comparison though. One is probably indian blackhead, one is probably german blackhead, I'm not sure what the others would be exactly. I'd go with whatever is the least expensive. There isn't going to be a great deal of difference for this application as long as it's acceptably fine.

 

You can coat the granulated BP or the coated rice hulls/media that you use. It sounds harder than it really is. All these fine flake aluminums are coated with stearin which makes them kind of waxy and sticky. You can fairly easily coat 5-6% by mass of the aluminum on them.

[Arthur]

IMO and only that small shells (2") need a lot of boost but less is needed as the size increases so a 4" shell needs little boost and a 6" needs none. as you get to 12 and 16" moderating the burst is a bigger problem. Are you using plastic hemis or paper ones? The break system is different.

[redbullzuiper]

I break my shells with flash powder. Well, my shells are just max 4" big. You get nice big breaks with it. I use 10 grams of flash in the ratio 6:4 (KClO4:Ai) in 2.5" shell, and 15 in a 3" or 4". I dust it on rice hulls. You get really big breaks with colored stars. And very symetric. Check my video's I posted in a topic here on APC.

 

Ive also tried to break my shells with black powder. But the break is much weaker and smaller. Ive once opened a 3" commercial shell. Inside it was black powder coated rice hulls with flash powder as booster.

 

My 2.5" shells are as big as commercial 3" shells with a flash powder break. Above 4" I woudn't break it with flash though. Maybe only a small percentage if your BP is too weak.

[NeighborJ]

MK, I don't know why I overlooked this option but KP burst charge is a very good option. It is a perchlorate based BP and delivers quite a bang when confined and burns slow in a pile. It has impressed me.

 

Not much is required to boost the reaction, I've used it to dust MCRH with a dramatic increase in burst.

 

By the way, a maroon is a type of BP firecracker. Usually made into a cube and reinforced with spiking.

Edited January 3, 2018 by NeighborJ

[MinamotoKobayashi]

x Mumbles: thanks, I will try to coat the rice hulls!

 

x Arhur

For the momment I use 3, 4 and 5 inches shells. Only paper shells.

 

x redbullzuiper: I think it is very dangerous to fill a shell with only flash. If a shell falls of the ground or simply there is too much burst in the mortar charge, the shell can auto-ignite and explode, and all of us know how dangerous is the flash powder. Only few grams can cut away the phalanges ...

 

x NeighborJ: You have a PM

 

 

 

P.S. I have found this interesting old thread:

 

https://www.amateurpyro.com/forums/topic/5219-alternative-burst-charges/

 

.. and two possible solutions to improve the shell break:

 

http://pyrodata.com/compositions/Black-Powder-Perchlorate

http://pyrodata.com/compositions/KP

[redbullzuiper]

 

 

x redbullzuiper: I think it is very dangerous to fill a shell with only flash. If a shell falls of the ground or simply there is too much burst in the mortar charge, the shell can auto-ignite and explode, and all of us know how dangerous is the flash powder. Only few grams can cut away the phalanges ...

 

Well, flash powder is not that dangerous

 

You can safely break small shells with flash powder. Commercial cakes are also made of flash powder. Some cakes, salute cakes, have 20 grams per salute.

And what about 3" or 4" salutes. They have sometimes up to 50 grams of flash powder. Its not that sensitive.

 

You can safely use it. Just handle it with care. Once inside the shell it safe enough to handle it. The only issues mostly come with mixing flash powder.

[Wiley]

This is an 8" bottom shot, and some if the components that stack on top of it. Such a report contains about 3lb of flash powder inside a very robust casing. Made the right way, using one of these as a stout base on which the shell is built actually enhances safety.

 

The mass of the flash powder does not matter. What does matter is the construction of the container that holds it.

[dynomike1]

Really the main thing to worry about flash is static elec. If it was that shock sensitive it would never make it out of the gun. I have rammed 70/30 about like driving a nail.

[OldMarine]

I use sali whistle to boost my breaks but only because I have it on hand. I don't think it is safer than flash except it is wetted when mixed and is granulated when used. Both lessen the chances of an accidental ignition and though the whistle is less brisant than an equal amount of flash it still will get the job done in smaller amounts.

[PyroDanTheMan]

While working mostly with 4" & 3" ball or can shells I have had good breaks using Benzolift to boost the BP coated rice hulls. Benzolift is supposedly safer than flash, but take precautions when using either of these.

[Milkman420]

Kinda off topic but i have a question. I put 35-40 mesh of spherical titanium in my salute rocket but it didn't give off any sparks. I coated the walls of the shell with elmers to hold the TI to give it a nice round shape. Am I doing something wrong?

[NeighborJ]

Yeah those doughnut salutes use NC to adhere the Ti to the walls. Elmer likely encased the Ti and kept it from igniting. Did you use grape nut Ti? +8mesh?

[MrB]

Yeah those doughnut salutes use NC to adhere the Ti to the walls. Elmer likely encased the Ti and kept it from igniting. Did you use grape nut Ti? +8mesh?

 

I dunno about that. I've been using liquid wood glue. Not elmers, since i don't have that stuff here, but generic waterbased stuff should be pretty much the same thing everywhere.

I pour it in to the empty shell casing, and then pour it back out, and stand it on a pair of lead pencils on top of the canister the glue came in, so most of it drips back out / in to the canister. When it's almost dry, i fill it with my FeTi. I don't have spherical stuff, but rather coarse shavings, but i think that would work to his advantage, not against him... Once filled it is put away, for at least half an hour, while i do something else. Then i pour out whatever shavings didn't stick to the walls, and fill the casing with the flash of choice.

If i don't want to have the bottom coated with FeTi, i start of with a tiny amount of sawdust, and just use a plastic mesh (windows screen to keep bugs out) to separate the wood dust from the Ti shavings when i pour it back out.

I don't know what they do to produce my shavings, but they are 3mm+ chunky stuff, and quite brittle.

I think the last bit above is the secret sauce. 35-40 mesh is positively tiny. It probably burnt to fast to make it into a visual effect.

But i'm no expert, it's just a guess.

[braddsn]

I have found that what Mumbles said above is true... all of the commercial shells (Lidu, Shengfeng, etc) that I have shot tend to be what I would consider "over broken". As a matter of fact, the 2.5" commercial shells that I have been shooting lately are broken so hard that many of the stars burn all the way to the ground (because they are travelling so fast). I certainly like hard breaking shells, but when they are broken too hard, you lose a lot of the color intensity. Boosting shells with flash or whistle is very safe, as long as you handle the flash carefully and avoid static discharge, friction, etc. The Chinese shells will have upwards of 10g of 70/30 in a 3" shell. Millions of these shells get shipped from China to the US, over the ocean in shipping containers, etc. And, the cases get thrown around and beaten up quite a bit. If dropping a shell would cause ignition, none of them would ever make it here. I have dropped many myself, it doesn't bother me. I make at least 400-500 ball shells per year, most of them boosted with flash. I have not had any problems. I douse myself with static guard and wet the floor when working with flash, and I am very gentle handling it.

[MrB]

"Over here" pretty much all commercial, consumer oriented pyro has a break charge entirely consisting of flash. The reason is quite simple. Stupid laws. The laws regulate the weight of live composition, and doesn't at all, care about what kind of composition it is. And if you are trying to make a rocket to sell to consumers that has a maximum of 75gr of live composition, what do you do? You use an AP based rocket fuel, and as little as you can to just barely get the rocket of the ground, and then you break it with flash powder. Leaving you the maximum weight available for stars. So now we have small, very point rockets, with lightweight plastic shells, that barely make it to a reasonable height, where they are well over-broken, and the stars bounce on the ground from 1 out of 10 rockets... All in the name of safety.

 

People should be forbidden from making laws about things they don't understand. (yes, i do see the irony of that statement.)

[Svimmer]

"Over here" pretty much all commercial, consumer oriented pyro has a break charge entirely consisting of flash. The reason is quite simple. Stupid laws. The laws regulate the weight of live composition, and doesn't at all, care about what kind of composition it is. And if you are trying to make a rocket to sell to consumers that has a maximum of 75gr of live composition, what do you do? You use an AP based rocket fuel, and as little as you can to just barely get the rocket of the ground, and then you break it with flash powder. Leaving you the maximum weight available for stars. So now we have small, very point rockets, with lightweight plastic shells, that barely make it to a reasonable height, where they are well over-broken, and the stars bounce on the ground from 1 out of 10 rockets... All in the name of safety.

 

People should be forbidden from making laws about things they don't understand. (yes, i do see the irony of that statement.)

you should be happy that you dont live in Norway i think we got one of the strictest law when i comes to fireworks.

[MrB]

Pfff. Here in Sweden, we wont let you have the hardest laws for anything long. We are out for you, and if not sooner, at least to 2019, rockets will be illegal.

The law does allow 50mm rather then 35mm for mortar shells, and i believe the live composition limit for cakes are the same, 1 kilo.

 

No wonder people are importing unsafe, illegal fireworks. Or make stuff them self. Again. Stupid laws.

But i honestly don't mind the ban on rockets that is coming. Takes care of one source of plastic litter i suppose. An i prefer mortar tubes, and shells anyway.

Not that a ban on rockets will prevent me from making some anyway...

[MinamotoKobayashi]

I decided to use KP for my 3", 4" and 5" shells. Between all the boosters, it seems to be the safer.

Surely I do not want that flash powder, whistle mix or benzolift ignite accidentally when I'm building the shell.

While I'm closing the hemis, the tissue paper bag containing booster will be punctured by the fuse.

This can cause friction.

Also tapping the upper hemis to pack the granulated BP or coated rice hulls can ignite the booster due to the

pressure and the friction.

And there is a big risk when I press with my hand the shell against the floor while roll it to spread better

the wetted gummed paper.

Finally sometimes happens that a finished shell fall off the table on the floor.

These are the four events that can ignite the booster and blow my hand away and not just that.

Sorry I cannot risk this!

Edited January 8, 2018 by MinamotoKobayashi

[Mumbles]

To respond to a post a bit earlier, most of those donut type salutes I've seen made use a spray contact adhesive. Using NC seems very wasteful when it's useful for so many other things.

 

MK, if you're worried about those scenarios causing an accidental ignition #1 you're way over exagerating the sensitivity of flash, whistle, and benzolift, and #2 should be equally concerned about KP. It probably has a similar sensitivity to benzolift and flash if I had to guess. All of the scenarios you described happen regularly in the manufacture of pyrotechnic shells, and I have yet to ever hear of an ignition from any of them.

[MinamotoKobayashi]

Hi mumbles.

There is another very important fact that I have forgot: the preparation of the mixes.

Between flash, whistle, benzolift and KP, I think that KP is the mix that have less chance of autognition during the preparation of the mix.

Besides this, KP burn slow when not confined, so also in the worst scenario of autoignition, the mix cannot deflagrate as the other mixes ...

[Mumbles]

If you're making any appreciable quantity, you screen all of them. There is no difference in preparation.

 

Keep telling yourself whatever you need to in order to justify your already formed opinion on flash, whistle, and benzolift though.