Alternative Burst Charges

[pyroguy1960]

Just a little background, I've been trying different methods to get big round symetrical breaks on my 4" shells. I've settled on using BP coated rice hulls 4:1 and a level 1/2 teaspon of 70/30 flash as a boost. I get somewhat decent results with this, but it's not always consistent. I use gummed paper tape to paste the shells and usually end up around 12 layers or so.

 

So I was thinking of other formulas I could coat onto rice hulls that would allow me to get the nice breaks without a booster.

 

Thinking of trying these two:

 

Shimizu KP

Potassium perchlorate.............................70

Hemp coal (or Paulownia coal).....................18 (I'll probably substitute commercial airfloat or pine, since that's what I have)

Sulfur............................................12

Dextrin.................................. 5 or to taste

 

This alternative I found on the forum

Potassium Perchlorate 50%

Potassium Nitrate 25%

Airfloat Charcoal 25%

Dextrin +4

 

Questions are:

 

1. Which is more powerfull?

2. Is there any other comp I can try that will alllow me to eliminate booster and just have something coated on hulls?

 

I know there is H3, but since all of my star prime contains sulfur, I need to stay clear of chlorates.

[BJV]

Just a little background, I've been trying different methods to get big round symetrical breaks on my 4" shells. I've settled on using BP coated rice hulls 4:1 and a level 1/2 teaspon of 70/30 flash as a boost. I get somewhat decent results with this, but it's not always consistent. I use gummed paper tape to paste the shells and usually end up around 12 layers or so.

 

So I was thinking of other formulas I could coat onto rice hulls that would allow me to get the nice breaks without a booster.

 

Thinking of trying these two:

 

Shimizu KP

Potassium perchlorate.............................70

Hemp coal (or Paulownia coal).....................18 (I'll probably substitute commercial airfloat or pine, since that's what I have)

Sulfur............................................12

Dextrin.................................. 5 or to taste

 

This alternative I found on the forum

Potassium Perchlorate 50%

Potassium Nitrate 25%

Airfloat Charcoal 25%

Dextrin +4

 

Questions are:

 

1. Which is more powerfull?

2. Is there any other comp I can try that will alllow me to eliminate booster and just have something coated on hulls?

 

I know there is H3, but since all of my star prime contains sulfur, I need to stay clear of chlorates.

 

I have tried many bursts in my round shell and I stick with BP 5 to 1 on rice hulls with a whistle booster.

I use from 4 to 5 grams of whistle mix. I do not use flash because of the bright flash.

Just my 2 cents.

BJV

[pyroguy1960]

yea I was just hoping there was a way to avoid the booster entirely....it's a pain in the ass...

[dagabu]

From all of the reading I have done, it seems that a flash bag is the only reliable way to break small shells big. There just isn't enough room in the shell to get the pressure up before it opens.

[TheEskimo]

I don't know where people get the idea that one can't break smaller shells with plain BPcoated rice hulls. I use that, and it seems to work just fine. Here's an example of one of my 3inchers using plain BPcoated grasseed. I don't know what others may think of the break, but they seem big enough for me, and are quite loud.

[Mumbles]

If you want a tunable burst, try this:

 

Potassium Perchlorate - 70

Charcoal - 10

Sodium Benzoate - 15

Dextrin - 4

 

6:1 on hulls

 

I personally use potassium benzoate, and commercial airfloat charcoal. Using a hot charcoal with that formula will turn you shells into salutes. Adjust the ratio until you get it where you want it. It's already pretty close for 4 and 5" shells right now.

[pyroguy1960]

Thanks mumbles, I'll give that one a whirl....how should this comp be treated, like black powder or should I take my safety measures up to flash handling level? Seems like a close relative to a whistle comp no? But toned down with charcoal and dextrin?

[AdmiralDonSnider]

yea I was just hoping there was a way to avoid the booster entirely....it's a pain in the ass...

 

 

From all of the reading I have done, it seems that a flash bag is the only reliable way to break small shells big. There just isn't enough room in the shell to get the pressure up before it opens.

 

It always pays to listen to people who have perfected a special type of fireworks. With regard to round shells it pays to listen to the Japs (there are others as well).

 

The KP charge will give magnificient breaks (without ANY need for a booster) in 4" shells given one listens to Shimizus lines on this charge and its use.

Firstly the correct weight ratio core material to burst comp is important (see the table in FAST). Given how little this is discussed in the net, there must be some ignorance about it (this also has to do with a vogue of other break techniques such as BP+flash - no judgement intended, just a fact). It makes a difference in the burst whether you stick to the correct ratios or just tumble damp hulls in KP for a few seconds.

 

Secondly tests have shown that the KP charge is contingent on heavy pasting to work optimally. Just a few layers will not yield good results.

 

Thirdly: stars have more to do with the appearance of a break than commonly assumed.

 

Start from there.

 

A charge very similar to KP but without sulphur is given in Baechle ("universal break"). I can dig out the formula if you want.

Edited September 29, 2010 by AdmiralDonSnider

[pyroguy1960]

Thanks ADS...I need to pick up FAST and really get more background. I've noticed in this craft there also seems to be many ways to skin the same cat as is apparent from this topic, I'm just looking for all the options and will ultimately choose the one that gives me the most consistent results, fits with my manufacturing style and with materials I have easy access too.

 

It's funny too that the interpretation of a good break will also vary from pyro to pyro, so many variables, so little time.

[pogue1000]

What is this FAST book you guys speak of?

[BJV]

What is this FAST book you guys speak of?

 

Fireworks: The Art, Science, and Technique

by Takeo Shimizu

 

BJV

[pyroguy1960]

Amazon has it for around 80 bucks...

[dagabu]

Is this the table you are referring too?

 

LINK

[AdmiralDonSnider]

Is this the table you are referring too?

 

LINK

 

No.

 

It´s the one on page 214 entitled "the optimum weight ratio for the composition of the bursting charge in relation to the materials of cores".

[dagabu]

Table 21.

 

http://www.pyrobin.com/files/table%2021.jpg

[pyroguy1960]

I tried 4" shells I made with KP burst tonight, seemed very powerful, but I couldn't tell you how it worked cause my stars all blew blind. It was a new blue star forumulation I used with about 6% ferrotitanium trying to make a tail. I primed them with mgal/green mix, then another layer of green mix on top of that. So I'm surprised they didn't light.

 

I don't think they shattered either, they are really hard dextrin bound stars made in a press with a star plate.

 

Anything I can do to fix these stars now? I was thinking of putting a larger layer of green mix on top of what's already there......are ferrotitanium stars hard to ignite?

[Mumbles]

You'll have to share the blue formula if you want much help. Chances are, I'd say your prime layer isn't thick enough.

[pyroguy1960]

oops...sorry here's the formula:

 

pot perc 61

cobber carbonate 12

parlon 13

red gum 9

dextrin 5

 

then I added 5% total batch weight of 40-300 mesh ferrotitanium

 

 

[AdmiralDonSnider]

These don´t seem extremely hard to light. The fact that they´re pressed could make it more difficult.

 

I´d rather use step priming e.g. 50:50 star comp-scratch mix, follow by 100% scratch mix. Don´t use processed meal, it often burns off quickly without providing sufficient heat. Also use a generous thickness for each layer. Even the hottest Si prime will fail if its layer is too thin.

[pyroguy1960]

I think that's all it was....just not enough prime.....I put a few more layers of prime on them last night and will try them again....

[WSM]

I know there is H3, but since all of my star prime contains sulfur, I need to stay clear of chlorates.

 

There are simple ways of solving these problems. I've seen H-3 on hulls used to burst shells with meal primed stars. The trick is to use tissue paper to separate the burst from the stars. When the burst ignites the tissue paper dissappears microseconds before the stars ignite and before the shell comes close to bursting. It does help to have well made materials (like a hard prime that isn't flaky or dusty, same for the H-3 hulls) and nice full shells that don't rattle when shaken. H-3 can be used; it just isn't as forgiving of carelessness as other methods .

 

Have fun, be safe and tell us about it!

 

WSM

[pyroguy1960]

I made up a few more KP burst shells today with the re-primed stars....I really didn't have much prime on them and I think the harder break caused them to blow blind. The KP seemed powerful though....I plan on shooting them tonight. We'll see what happens.

 

I do know that H3 has been used with comps containing sulfur succesfully, however I don't have any pot chlorate and I pack my shells fairly tight, who's to say the tissue paper won't rip and start rubbing around in there. I figure if I can solve the issue with a more compatable burst so be it. Don't need shells that are overly sensitive to impact if I can avoid it.

 

I'm kinda a sissy when it comes to safety, which is why i started looking for alternatives to the flash booster, just not comfortable putting myself in any more danger than I have to. I'd like to get out of the flash business all together, after seeing what a small 20 gram salute of that stuff is capable of, it really kinda puts the fear of god in me. Can you image a pile of flash going off in your face.....I shudder to think about the damage that stuff is capable of doing. Just not worth the risk to me.

[pyroguy1960]

Can't say I'm 100% confortable with the KP either for that matter

[pyroguy1960]

So the results are in. The problem with the stars not igniting was indeed too little prime. The re-primed stars all lit fine with the KP break.

 

The KP break itself was perfect, nice round and symetrical, not too big not too small. Definately think I've found my break of choice for 4" shells.

 

By the way I made the KP with commercial airfloat and it was coated 5:1 on rice hulls and I did do a little extra pasting on the shells. Put enough layers on them so it had only about 1-2 mm clearance in a standard size 4" gun.

[AdmiralDonSnider]

 

The KP break itself was perfect, nice round and symetrical, not too big not too small. Definately think I've found my break of choice for 4" shells.

 

 

 

Good to hear that. Once you found a setup that works for you, make sure to write down notes about all the variables. Also try to keep the chemicals consistent (especially: same charcoal, same particle sizes). The charcoal is a tricky variable in these break comps.