Newb Need help with burst

[pyroguy1960]

I just made my first shells, I followed a 4 inch plastic ball tutorial on skylighter. However when the shell broke the stars just kinda fell, the break wasn't round and symmetrical at all. I used commercial 4FG coated rice hulls for burst. The zinc stars I used were pretty heavy. Also in looking back at the tutorial he mentioned using slow-flash boost. I didn't know what that was, so I left it out as I've heard flash was dangerous.

 

However I'm thinking I need a booster for these shells to get a nice round break. I've read all the safety articles on the site and the ones about flash seem to be mostly people arguing back and forth about what they do and do not do. No real instructions for the newb on how to prepare it in small amounts safely for legitimate use in a shell.

 

So as I gather, I can use either:

 

7/3 mix of potassium perclorate/aluminum powder

OR

2/1/1 mix of potassium nitrate/sulfur/aluminum

 

What I plan on doing is diaper mixing a small amount before I close up the shell. Sprinkling it on the the BP coated rice hulls. Will this solve my break problem?

 

Also here is what I'm sure is a real newb question. How do I make a salute? I tried filling a shell with BP rice hulls only and found that is obviously not the way to go about it, it sucked.

 

If flash powder is the way to make a salute, how much and what comp would you use for a 4 inch shell? I'm 99% sure there is no way you fill the whole shell with a flash mix, I could fill the whole shell with some 2FG BP, but seems like a waste of alot of black powder. If I make a small amount of flash for a salute, what do I fill the rest of the shell with to give it the proper weight and keep the flash in place?

 

I'm aware that perhaps I should not be even messing with flash, but it seems I need it to some respect no? if I want to have nice round breaks and loud salutes?

 

Thanks for any advice for the new guy....

 

By the way, here is a vid of the shells....the camera work is shaky and I used a little bit too much lift charge I think. 2 oz of commercial 1FG, should have used 1.5oz but I figured they were heavy stars so...

 

http://www.youtube.c...h?v=Tuwa3T0luaY

 

Attached are a few construction pics so you can see if I did anything wrong there...

 

Edited July 25, 2010 by jms04081974

[Arthur]

First remember that the break system for plastic shells is different from that needed for paper shells.

 

You will need flash and maybe whistle powder too to get a really hard break from plastic hemis.

 

The usual reason for dissuading people from making flash is that beginners only want to put flash in tubes and cause a nuisance which attracts the "men in boots" and makes the hobby difficult for all.

 

Bring the fuse tube to the centre of the hemi and put a small tissue bag of flash powder on the tube exactly in the centre of the ball. Then select by trial the right amount of flash to break the shell hard enough but not over break it or shatter the stars.

 

there really is at least one good method detail for every person who makes shells, so in the end you have to find the method that works for you.

[pyroguy1960]

Thanks for the reply, this is definately a good start, however it somewhat raises more questions, keep in mind I know nothing about it. So a generic answer really doesn't help me and given whats at stake if I'm wrong I was hoping for specifics.

 

Also let me assure anyone who answers that I'm a not some meathead kid who's just looking to make M80's to blow up mailboxes, I'm in my mid 30's and a very reserved person who has a very healthy respect for the compounds we deal with and just would like to know the proper ways to do legitamate things in the hobby. Like having a good break on a plastic shell and making a proper salute shell.

 

Let me ask this way with specific questions.

 

1. What is the difference between breaking paper shells and plastic ones?

 

1a. Am I right in assuming that not having a booster is the problem with my shells?

 

2. Which formulation that I listed above is less dangerous to start with?

 

3. Which formulation that I listed above is more powerful?

 

4. Are the formulations I listed above even correct?

 

5. Are there any do's and don'ts for the 7/3? (ex. Don't get it wet or you will die! || Don't put hot glue on it!)

 

6. Are there any do's and don'ts for the 2/1/1?

 

7. The next few questions deal with How exaclty do I make a 4" salute shell

 

7a. Is using flash even the proper way to make a salute shell?

 

7b. Do I fill the whole shell with flash when making a salute?

 

7c. If i don't fill the whole shell with flash to make a salute, what do I put in the shell as filler? And how much of each comp listed above is a good starting amount for a 4" salute shell?

 

 

I would be extremely grateful for anyone who answers these questions completly and honestly, it may save my life. Also please note that I know the responsibility lies completly in my hands, so any advice given will absolutely not be held against anyone.

 

Thanks so much for anyone who is willing to take the time to explain this to me.

Edited July 25, 2010 by jms04081974

[Peret]

1. What is the difference between breaking paper shells and plastic ones?

 

I think the difference between paper and plastic is largely ideological. You can get excellent breaks with either. However, there is no doubt that a well pasted paper shell often fragments better than plastic, which will tend to split along the weakest point, usually the glued equator. I've had a plastic shell break badly and on recovering the remains, found that the top (non-fuse) half is not even scorched, showing that it blew apart before the fire reached and ignited the stars in that half. In that particular case I'd used several layers of fiberglass strapping tape well rubbed down, but there was no trace of tape left on the hemis. So I speculate that the burst gas escaped out of the equator joint under the ball of tape, inflated it, and lifted the whole lot off cleanly, leaving the shell with nothing holding it together. This will always be a possibility with adhesives that remain sticky and don't set hard. With paper hemispheres there's no strength in the joint, it's all in the pasted paper. If it's done well the paste sets hard and there's no particular axis weaker than any other, so the gas has no chance of escaping confinement except by breaking the paper. I've test-burst small paper shells in a 50 gallon drum and found they break into multiple small pieces, none of which looks anything like a hemisphere.

 

1a. Am I right in assuming that not having a booster is the problem with my shells?

 

I don't think lack of booster was the problem so much as that you used what appears to be duct tape to spike the shells. c/f my experience above, you may just as well have used nothing. There's nothing to stop you papering a plastic shell of course, it just takes longer.

 

 

 

7b. Do I fill the whole shell with flash when making a salute?

 

Not if you want to live. What makes flash dangerous is that at some critical mass, thought to be about 2 ounces, it transitions from burning to detonation. A full 4 inch shell would take 8-10 ounces, well over that critical mass, and you'd be in jeopardy from the moment you started mixing it.

[Cookieman]

Looking at your video it looks like your shell broke at a weak spot, most likely the equator. You don't mention how you attached the two equators, Xylene, PVC cement? Their's alot of glue inside your hemi. Did you glue all your stars on the inside? I also use plastic hemi's and still paste them with 3 layers of gummed kraft. What you want from your break is to build enough pressure in your shell to get a good symetrical pattern without blowing your stars. You should try a more energetic burst charge such as H3, without any booster. Here is a good break from a plastic shell from one of the members.

 

My link

[Mumbles]

Peret, I think you're getting self confine and detonate confused. It will go off and make a report when in a pile at 2oz (probably less than that). Very large salutes still don't detonate. I've seen salutes approaching 50lbs, and it still has the low thunderous boom of a deflagration. That's not to say you'd be any less dead from an 8oz flash deflagration vs detonation. It is not going to spontaneously explode or anything like that.

 

As Peret said, you can get great breaks from either paper or plastic. You just have to go about it in different ways. Most people eventually transition to paper. It is certainly more ecologically friendly. Some say you get better breaks from it. I think it's more that paper is a little more forgiving and much more traditional. Much of the legwork and experimentation has already been done so optimized methods are widely known. Plastic shells are still relatively new, especially on the amateur market.

 

You're at least doing some things right. The fact that the shells survived that lift shows that they're well constructed. They actually break relatively spherical. While not huge, they're certainly not bad. They had a decent pop when they broke. The construction pics, save for the duct tape at the end look pretty good to me. Booster would probably help. Pasting with paper may also help too.

 

 

2. Which formulation that I listed above is less dangerous to start with?

 

I don't know that one is inherently safer or more dangerous than another. 70/30 is more powerful, and probably better suited toward the salutes. 2-1-1 is slower, and is maybe better suited toward breaking shells. It will probably be a little more forgiving. You'll need to use more, but it should be a little bit easier to tune. Some recommend tumbling the burst in flash powder to coat the hulls evenly. I don't know how much to tell you to start with really. Maybe 2g of 70-30, so 4-5g of the 2-1-1 flash? I don't use boosters on my ball shells, nor do I really make plastic shells, so it's a little hard to give advice.

 

 

3. Which formulation that I listed above is more powerful?

 

70-30

 

4. Are the formulations I listed above even correct?

 

Yes.

 

 

5. Are there any do's and don'ts for the 7/3? (ex. Don't get it wet or you will die! || Don't put hot glue on it!)

 

6. Are there any do's and don'ts for the 2/1/1?

 

The biggest don't is losing respect for flash. It's dangerous stuff, though it can be worked with safely. I don't like mixing it in low humidity, I shoot for 60% RH or higher. I also douse myself, and work area with static guard. As I said, I don't use boosters, but I don't like storing flash powder. I make only as much as I need for the build session. I try to avoid places where it can be subjected to friction or impact. I line everything with paper. I work on grass, not gravel or concrete. Flash is pretty powdery stuff, it will float around when making it. Places like shell seams also are a place I try to avoid. I like to soak down my work area and contaminated paper when I am done, though that may not always be enough. I would probably avoid hot glue coming in contact with it. All of the operations that involve hot glue can usually be done ahead of time.

 

 

7. The next few questions deal with How exaclty do I make a 4" salute shell

 

7a. Is using flash even the proper way to make a salute shell?

 

7b. Do I fill the whole shell with flash when making a salute?

 

7c. If i don't fill the whole shell with flash to make a salute, what do I put in the shell as filler? And how much of each comp listed above is a good starting amount for a 4" salute shell?

 

Yes, flash powder will be helpful in making salutes. Filling a shell with BP will also work, but requires more confinement, and a few different methods. It's different from flash salutes. There are different ways to make salutes, but generally at least half, if not more, of the shell is filled with flash. You can use a mixture of your coated burst and flash if you don't want just straight flash. Other inert things, like uncoated rice hulls, rice crispies all work too.

 

You may want to try smaller salutes to start with. You'll be very surprised at how loud an how much power these things pack. I made up half a dozen small (by my standards) salutes for the 4th this year. They were only 2" long, and about 1.5" ID. About the size of a consumer shell. I was setting off car alarms, and they were echoing for miles. They were way too big for where we were shooting. They had around 30-50g of flash powder in them. 4" salutes contain somewhere between 200g and a pound.

[pyroguy1960]

Thanks so much for everyone for taking to time to reply with those detailed responses. Very helpful.

 

Just to answer the questions that were asked of me, I did use PVC to glue the hemi's together. I also used hot glue to put the stars at the equator and the rest were sort of just fitted in. I was however perhaps a little too liberal with the glue at the equator.

 

So here is what I gather, duct taping the shells is not a good idea or perhaps maybe it just doesn't help anything? I just did it to make the shells look a little better. It also sounds like I might be better off doing some pasting on the plastic shells to help build more pressure so they explode out in all directions and not at just the hemi.

 

It also sounds like it's ok to experiment with very small amounts of 7/3 with 350 mesh AL to beef up the burst charge a little.

 

And as far as the salutes go, start small, filling the rest of the shell with rice hulls or rice crispies. I did notice that it seems hard to obtain the 2500 mesh dark AL for making salute flash, can I somehow grind the 350? Or do I have to take the rock tumbler, aluminum foil, charcol approach to making dark AL?

 

Thanks again to all.

Edited July 26, 2010 by jms04081974

[Peret]

Peret, I think you're getting self confine and detonate confused. It will go off and make a report when in a pile at 2oz (probably less than that).

I'll be the first to admit I'm not an expert in explosives and only going by what I've read. Perhaps I'm getting confused between flash initiated by flame and flash initiated by shock. Whatever, I prefer it not to be initiated in any manner when it's near me.

[jwitt]

I'm only just learning as well, so my word is not absolute (research has been going on for a year, been on this site since about Jan 2010, and built shells from May to now). But, I've managed to pick up some info.

 

• Energetic compositions (flash, BP, whistle mix, etc) can be set off by flame, friction, impact, or static. Different mixtures have different sensitivities to these things- some imaginary composition might be very very sensitive to friction, but maybe "only sort of" sensitive to static. That's why we must research every composition we make before mixing or using it.
• Energetic compositions have a "critical mass" like it's called above- a mass at which the material will "self confine." When it self-confines, a pile in the open will deflagrate as if it were in a casing of some sort. Like BP- touch off a little pile of it, and it will wooooosh. Confine that same pile in some way, and it will, for a tiny period of time, burn, then a "feedback loop" of pressure and hot gasses starts and ka-boom we have a deflagration. Anyway, you would need a big pile of BP to have it self-confine (although a burning pile of BP could really damage property and fleshy critters in the vicinity). Flash powder, on the other hand, will go woosh really fast in a small pile, but a slightly larger pile will self-confine...an amount small enough to make mixing flash a potentially lethal experience.

Bad things about flash as a booster:

 

• Very fast stuff. It might blow your stars blind- throwing them so hard that they either don't light because flame propagation hasn't occurred inside the shell, or blowing them out as they shoot through the air.
• Very bright flash. Some stars (like Zn) are "subtle" and don't have super high light output. Your eyes get hit by a bright white flash, and the stars seem kind of whimpy up there.
• Potentially a very loud boom- which we may, or may not, desire for a given application and shoot site.
• And, of course, let's not forget safety concerns!

I've been using whistle mix as a booster, and only using flash in a couple salute shells. Whistle mix is also a very sensitive composition, "roughly equivilent" to flash from what I know. That means the same safety precautions must be observed when working with it. It's not quite as powerful as flash- a good thing for boosting a break charge. It doesn't create a bright flash- also a good thing. It's also slightly cheaper to make, but using a couple grams at a time, that's really irrelevant. My 3" paper ball shells are boosted with 2-6 grams of whistle mix, depending on the application. (Softer breaks like willows or color stars I don't want to blow out get about 2g, harder-breaking shells get more bang bang). Also- my BP hulls were made with what I'd call "medium quality" or even "crappy" BP (would take about 65g to lift a 160g 3" shell to about 300 feet) so I really need the booster to get a round break. Now that that burst is exhausted, I'll be making better stuff, and will probably adjust boost accordingly.

 

I hope I've helped a bit.

 

Here's a thread for ya- my newb question on burst charges

 

The folks here have also provided really in-depth answers to other questions of mine, and it sounds like you'd benefit from those as well. Scrolling through the newbie forum, you'll find the threads in the first 3 pages.

Edited July 26, 2010 by jwitt

[Bonny]

 

 

And as far as the salutes go, start small, filling the rest of the shell with rice hulls or rice crispies. I did notice that it seems hard to obtain the 2500 mesh dark AL for making salute flash, can I somehow grind the 350? Or do I have to take the rock tumbler, aluminum foil, charcol approach to making dark AL?

 

Thanks again to all.

 

 

Just use the 350 as is...the salute will still be nice and loud. I've made salutes with 250mesh atomized Al and they were loud enough.

Don't bother trying to make dark Al or ball milling what you have. Milling Al that fine can be VERY dangerous.

[hst45]

jwitt brings a good idea to the table, that of using whistle mix as a break charge. It has two advantages for me.

 

1) I find whistle more forgiving than vitamin F. A given flash break charge + 20% may blow stars blind, whereas whistle plus 20% doesn't seem to. In other words, if you have say half a gram too much flash it might be problematic, where whistle seems to me to be less likely to blow stars blind. This wouldn't be a problem to a shell builder who regularly produces a good number of shells of a particular size and configuration and has his breaks well dialed in, but for the occasional one-of-a-kind shellbuilder such as myself I don't have a really dialed-in formula for every size and weight of shell. It gives me one less variable to worry about.

 

2) I don't store flash. I don't have a problem however with keeping a small quantity of whistle mix made up and stored in the magazine, so I can easily grab a "pinch" of break charge if I decide to build a shell or two one night. I know that nothing is going to happen to stored flash, it just weirds me out to keep it around.

[Peret]

Peret, I think you're getting self confine and detonate confused.

Thanks, Mumbles, for that pointer. I was confused but I see it now. I assumed it was detonation because the reaction is faster than the speed of sound - but that is, of course, the reason why it self-confines in a loose pile, because the pressure wave can't escape fast enough.

[pyroguy1960]

Understood I didn't know those rough granulations were ok for salute flash, I'll use the 350. Also i don't plan on storing it at all, I plan on diapering just what I need for a shell, right at the time I'm ready for it.

 

Thanks again to all for the advice...

Edited July 27, 2010 by jms04081974

[jwitt]

Yeah, storing flash seems kind of pointless, seeing how simple it is to mix. On the other hand, though, you've gotta be super alert every time you need some, so I guess it might actually be a toss-up? Making salute shells, I calculate how much I'll need and mix it, then immediately load it into prepared shells. (ball shells aren't so handy for making salutes, gonna do cylinders next year.)

 

I have been storing Sodium Benz whistle mix however, since I used 2-6g as a booster in the 3" balls. One scoop of a certain size is about 2g, so it was easy to get shells on an assembly line, go grab the tub of whistle, dose 'em up to specs, then send the tub back to storage.

[dagabu]

I take what I need from the whistle canister and put it back in the mag. Here is a movie that shows why this is so important.

 

MOVIE

[Cookieman]

I take what I need from the whistle canister and put it back in the mag. Here is a movie that shows why this is so important.

 

MOVIE

 

 

The shield didn't stand a chance.

[dagabu]

I make a kilo of whistle at a time, that's TWICE what was in that video.

[pyroguy1960]

An update on this, I used gummed kraft paper on the plastic shells and a small amount of 2/1/1 booster.....worked wonders, the breaks were much more symetrical. Still could have used a little more, but was almost right on the money.