Different Boosters for Shells

[Guest PyroManiac1]

As to get straight to my question. Why use a slow flash booster in your shells opposed to a fast perchlorate flash. Theoretically you would be able to use much less perchlorate flash as it is stronger therefore making it more cost effective. If you use a miniscule amount, you won't really need to worry about it breaking your stars. Again this is all mostly theoretical, there must be a reason for slow flash. Could anyone tell me this?

[SharkWhisperer]

It's one more tool in your pyro burst kit. It generally falls between BP and regular FP on the power spectrum, closer to one end than the other depending on the specific formulation. Some vary the strength/formulation of their BP. Some spike their usual BP with varying amounts of FP to ramp things up a bit. A pure flash burst is a salute, and risks blowing blind many types of stars. Usually the burst is not just in a localized central space, but is interspersed amongst your stars/inserts/effects to assure flame transfer while pressure is building up before shell disintegration; this would be difficult with regular FP. Burst comp selection is also dependent on shell size and configuration.

 

"If you use a miniscule amount, you won't really need to worry about it breaking your stars". Ok. But you do need to consider whether it will give you the desired symmetry, power, and ignition of your shell and it's contents. It's difficult to balance all three using a "miniscule" pure FP burst.

 

I'm sure others have additional specifics to add to this answer...

[Guest PyroManiac1]

I am planning on using rice hulls for my burst, and wanted to sprinkle a little booster on top. I didn't mean a pure flash burst. The rice hulls would ensure ignition while the flash would ensure a nice strong break. In this specific case would you still use slow flash opposed to perchlorate? I am talking about a 3 inch ball shell by the way. Edited June 12, 2020 by PyroManiac1

[Richtee]

If the flash cracks the shell before the rice hulls fully ignite...well, yer gonna blow blind. Timing is important and flash is too fast.

[Guest PyroManiac1]

I see, Thank You

[kingkama]

Perchlorate flash absorb Heat and it's too fast so a lot of stars go blind. The best is use coarse perchlorate and different kind of aluminum, sometime add some bp can help.

[Mumbles]

The idea behind flash boosters is to spread fire faster, make the burst burn hotter, and ideally generate a higher internal pressure before the casing ruptures. One of the benefits of slow flash is that it's easier to dial in and it's more gentle. 70/30 can be kind of touchy. It can more easily over-pressurize a shell or cause the casing to prematurely or assymetrically rupture. By using something slower, I feel like you're more effectively pressurizing a shell instead of shocking or shattering it. Some shells can handle straight 70/30 flash bursts; see spider shells for instance. Even spider shells are really a relatively small flash charge and a large proportion of polverone or other filler to help spread fire, produce more gas, and actually help with the break. If you look at most commercial flash bag broken shells, or at least the good ones, a majority will use a larger quantity of a more toned down break. These flash break formulas generally have something like nitrate as a portion of the oxidizer, some coarser or atomized aluminum, often sulfur, etc.

 

The other, often unthought of factor is that of dilution. How the flash is distributed matters. If you add 2g of 70/30 to the center of your shell or in a flash bag, it's going to break harder. If you distribute that same 2g over the say 100g of coated rice hulls in your shell, I doubt you'll notice that much of a difference. Likewise if that 2g migrates somewhat, but asymmetrically, it's going to negatively impact your break. Now if you have say 10g of slow flash added, even distributed it's going to have a greater contribution in my opinion. There is more metal around to heat all the gases up and make the burst harder. For a while it was common to pre-coat your hulls with slow flash before filling the shell. Symmetry in filling, pasting, and breaking all effects the symmetry of the final effect.

 

I don't really consider cost as a factor in anything I do. This hobby is one step from literally burning money. The difference in the amount of slow flash vs. 70/30 is miniscule on a hobbyist level.

[Guest PyroManiac1]

So 2/1/1 (KNO3, AL, S) is what should be used in shells from now on. Thanks everyone. Edited June 13, 2020 by PyroManiac1

[SharkWhisperer]

So 2/1/1 is what should be used in shells from now on. Thanks everyone.

I'm a little unclear on what your 2/1/1 ratio refers to. Brother, you must be specific, clear, and without omission/oversight when discussing comps and configurations. Please clarify.

 

Also, there's a huge difference in burst requirements depending on shell size, configuration (canister vs round), and contents. There is not, in my experience, a one-size-fits-all burst solution/configuration.

 

You're still talking about 3" ball shells? Like Mumbles mentioned, using spider shells as an example of when you can use a pure FP burst, there's a wide variation in what comp(s) you can use (optimally or just get away with) to get a desired effect from your shells. If you're mixing things up in terms of size, type and effect, well, you need to test it out. Safely. Change something/anything in construction or formulation, and it needs to be re-evaluated so there's no surprises.

 

I've made some impressive FP burst crackle "grenades", aka "ground effects/gerbs" that surprised me because the payload took fire reliably with a hard burst. Other times, I've blown blind (hard to light) stars with a moderate burst and what I thought was sufficient priming (aka a failure).

 

It's an art as well as the science. Consistency and predictability are key.

 

If you change anything at all, your approach and effect needs to be tested, rationally, before demonstrating in the public realm (aka a show for your pals).

 

Fun, fire, and safety! The last in the list can never be under-rated.

[Carbon796]

So 2/1/1 is what should be used in shells from now on. Thanks everyone.

It's not necessarily what should be used from now on, but one common avalible choice out of many. On a smaller shell like a 3", its preferable to use straight BP as the break charge. Rather than coating it on media.

 

3/2/1 is another very similar/popular SFB. Some SFB or forte nitro type comps are also formulated to produce slag or dross. Which could aid in star ignition. They also generally provide a more gaseous output than a 70/30 booster would.

[Guest PyroManiac1]

Apologies, I edited the post. The only reason I am using rice hulls in my 3" ball shells is I have found that mine in particular are extremely fast, just as my granulated powder, so I have no problem using them as they are lighter and in my case just as powerful. I wasn't implying that one size fits all shells but in my case I am only making 2" and 3" so I meant I will be using slow flash for those two types of shells. Edited June 13, 2020 by PyroManiac1

[Carbon796]

Using straight BP, rather than watering it down with rice hulls. May reduce your need for a booster. Even if they are just as fast, volume for volume your giving up burst strength.

 

There is no real practical reason or benefit, to building lighter shells.

Edited June 13, 2020 by Carbon796

[Guest PyroManiac1]

There is no real practical reason or benefit, to building lighter shells.

I have been deconstructing many professional Chinese shells and watched some tours of some Chinese factories and it seems they always use rice hulls as burst. I doubt they would do this for no reason. I am just trying to replicate what the professionals are doing. Rice hulls fill up shells therefore saving powder, it also saves on lift as you know lift is based on percentage of the shells weight.

[Arthur]

It's impractical to weigh out the miniscule amount of flash needed in a 3" shell. Having flash inside also increases the possibility of having a burst in tube and destroying a mortar.

Consider using fast BP to fill a tiny bag of paper on the inside end of the time fuse, maybe 1/4" dia by 1/4" long. Thats a paper wrap made round the time fuse.

 

I have used 70/30 flash, but only the amount that sticks by friction on the end of the 1/4" fuse, I ceased to use if because things worked without it once my powder was reliable.

 

Added:

usually it's very different whether you use plastic or paper hemis. I've always used paper hemis.

Edited June 13, 2020 by Arthur

[kingkama]

It's a choiche to use flash break or Bp straight or on rice hull, all works in relation at the spiking or pasting works, if you read Shimizu he use ever a flash bag inside the ball shell, traditionally the ball shell was filled in rice hull bp covered, italian like use flash bag and polverone or granulated flash and bp or booth putted on Ground cork, sure is that the most don't use 70/30 with perchlorate and black aluminum (mix reserved only for salute) there is Mg, aluminum of various kind and dimension, perchlorate and/or chlorate, someone like to add sulphur other red gum or charcoal, the target is the same for all, the way to reach it many.

[Guest PyroManiac1]

Yes, I do use paper hemispheres as well. I would never go for plastic. I think I'll stay away from perchlorate flash altogether (50/50 MgAl/KCLO4). I think slow flash is the better way to ensure an even break. Edited June 13, 2020 by PyroManiac1

[SharkWhisperer]

Yes, I do use paper hemispheres as well. I would never go for plastic. I think I'll stay away from perchlorate flash altogether (50/50 MgAl/KCLO4). I think slow flash is the better way to ensure an even break.

Why don't you try it with BP granules or BP-coated rice hulls alone as burst first, and see if you really do need a more powerful break--that an extra layer or two of Kraft pasting on your round 3" shells wouldn't solve?

 

If your BP's good enough to lift the shell to a safe/appropriate height, it's more than likely sufficient to burst a 3" round paper shell, whether alone or coated on rice hulls to save a little weight.

 

If your BP is insufficient for decent lift/burst, then you need to make appropriate modifications to your BP manufacturing process and get it working correctly before considering band-aids.

[gregh]

A lot of the commercial Chinese shells do not use bp on the hulls for burst. Its a KHP mix that is more powerful, like KP and more importantly for them, dirt cheap.

[rellim]

Why not add a bit of whistle? It makes a lot of gas. Easy to granulate with 3% dex.

[Pyrofire2]

Hello everyone,do you know how much burst charge is used in chinese shells?For ex.in a 6,because i have read in warimono shells there is more break charge ,Shimizu Says 270g for 6shells.But how much kp break charge do chinese use?Thank you a lot.I cant find this anywhere.

Ps i really dont understand what is exactly warimono!

[Pyrofire2]

I Think kp or H3 burst charge have no need other booster.Is not used bp for shells Under 6”..

[Arthur]

The usual variant in burst is the proportion of powder to hulls. In a big shell I've used 1:1 BP to rice hulls, In a smaller shell I've used 3, 4 or 6 parts of powder per part of hulls.

 

The flash bag on the fuse end is only to get fire quickly to the break charge, the break charge powder ratio determines how powderfully the shell bursts -too fast and it may blow blind too slow and it may horsetail.

[Pyrofire2]

Uhm black powder for 3shells do you use?