Aerial Shells

[tentacles]

Sodium bicarb would actually help to *cause* a reaction with aluminum; aluminum is more resistant to acids than it is to bases.. Although boric acid isn't a true acid. It's possible that the difference between reaction vs not is the water used, or possibly coated aluminum (I'm sure even some atomized aluminums have some sort of coating).

 

I would recommend always using boric acid when you've got nitrate/aluminum mixes - there really isn't any reason not to. H2BO4 is cheap and you need very little to make a saturated solution.

 

jerr: Did you use tap water or distilled water to wet the comp? If tap water, do you have hard water or soft water? Know the pH?

[Seymour]

Where's the boric acid?

 

Jerronimo stated that (s)he used Gum Arabic to bind these stars. Gum Arabic forms slightly acidic solutions, and like Boric acid, can prevent the nitrate Al reaction occurring.

 

I have tried to get the good old nitrate/Al reaction to occur with my Atomized Aluminium, and with Barium, Sodium and Potassium nitrates I have failed to get it to warm up or give off any NH3. While I'm sure it is a possibility that the reaction could occur, I think that unless someone is making many tens of kilo's, or are using a particularly reactive Aluminium, there is little risk of it igniting. However, Ammonia smells a bit off and some people have experienced the reaction. If someone is going to skip acidifying the mix, I urge them to test their particular chemicals in a small batch first, to see if they do react, and if they do, then definitely adding boric acid (pr an alternative) is a wise idea.

 

Even if they don't react, it's still nice to have another safety net, although I would not personally consider it a priority.

 

If you really want to see a reaction that needs some kind of buffer, add Ammonium perchlorate to uncoated Magnesium/Magnalium and then add water. Watch it foam and make the place smell like a public toilet that the cleaners have ignored for a month.

[Mumbles]

I have no idea why I was getting reactions. I've never personally gotten a reaction with D1, but have with similar compositions. I use only distilled water, and what I like to think are relatively pure chemicals. There are just some compositions that don't exhibit the reaction as regularly as others for some unknown reason. Despite having the exact same chemicals, some regularly have reactions, and some don't.

 

Tentacles is right. Sodium bicarbonate, at least in my opinion, actually promotes the reacting by contributing hydroxyl ions. Despite popular belief, I'm of the opinion that boric acid is not negated by bicarbonate. It's not strong enough to protonate bicarbonate, so it's not "used up" in conventional ways of thinking. Adding a boric acid solution to a bicarbonate solution confirms this. Regardless or not if it's used up or not, it at least prevents reactions for me that would have occured otherwise, so that' all I care about.

 

I also don't mill any of my glitters. I should start milling my KNO3, but thats another story. I like longer, more delicate looking glitters, which I don't get if I mill the components. This is just my experience, and others will vary. I also build bigger shells generally, which are somewhat more forgiving in terms of burn time and spread.

[psyco_1322]

I once had a Al/Nitrate reaction occur. It was shortly after I started pyro and began making my own stars, I can't remember what composition it was though. I had read about the reaction and noticed the batch heating up after I got them cut. I quickly too then outside and left them to dry, they were fine after that, didn't catch fire or anything.

 

I often, in mixes like D1, get a rotten egg smell. I never had any problems with it until recently. I might have been that I dont put boric acid in it anymore. I had this case really bad when I rolled up a batch with 5 micron atomized Al. Left them out in the sun to dry came back and they had split open, and it looked like stuff had oozed out of some of them. They had major fall out problems with a poor glitter effect.

 

I'm still puzzled to how the boric acid is not reacting with the bicarb. Is it just not strong enough?

[Mumbles]

I'll see if I can explain this.

 

Yep, not strong enough. Boric acid isn't a convential acid that produces H+ ions, rather it soaks up OH- ions, which consequently increases the acidity of the solution. Being that it isn't conventional, it's hard to get a true pKa of it, but there are some figures around that allow comparisons. In order to "use up" the bicarbonate, it has to be a stronger acid than H2CO3, which according to the pKa figures it is not. It's like adding HCl to sodium acetate, you generate acetic acid as noticable by the odor. If you add acetic acid to sodium chloride you do not form HCl.

 

This may seem abstract, but you have to think about everything in terms of acidity. Bases in this sense are just weaker acids than water. In this same sense boric acid is a stronger acid than the carbonate ion, so it will protonate it to bicarbonate. So, boric acid will protonate carbonate to bicarbonate, but not bicarbonate to carbonic acid. As such it exists as the bicarbonate in solution. I feel however that the use of carbonates could cause issue. Luckily for us, all the common carbonates have poor solubility, and are bound to divalent metals, so there is equilibrium pressure to keep regenerating any boric acid that is used.

[psyco_1322]

Ok, I understand now. Makes sense.

 

 

Here is a picture of my multi-break. Probably shoot it sometime this week, hopefully. Along with a few 4" balls.

 

Pic:

http://pyrobin.com/files/s4024558.jpg

Edited December 18, 2008 by psyco_1322

[Gunzway]

Ok, I understand now. Makes sense.

 

 

Here is a picture of my multi-break. Probably shoot it sometime this week, hopefully. Along with a few 4" balls.

 

Pic:

http://pyrobin.com/files/s4024558.jpg

What's wrong with twelve or thirteen days from now?

[psyco_1322]

I'll make something for Christmas, not sure what. I have a mini multi break I made completely out of toilet paper tubes, and fiberglass tape. I put some work into it, maybe more than this one. Its setting on top of a 1lb whistle, to get it high enough. Just hope the rocket hasn't gone to far south.

 

13 days is like a life time when it comes to making something for an event. I always wait up until about 3-4 days before and then decide to make something. Last year, I made two 4" shells in about 2 1/2 days and shot them Christmas night. I'll think of something to make/shoot.

Edited December 18, 2008 by psyco_1322

[tentacles]

Actually, I've very recently been informed of a pending new years' party that we will be attending, with a local pyro fan, so I need to make some shells.. And beg Bonny to borrow a 5" gun maybe.

 

I'll probably just cut up a bunch of some glitter or other, dust and dry, already have plenty of lift and burst made.

[Seymour]

13 days is like a life time when it comes to making something for an event. I always wait up until about 3-4 days before and then decide to make something

 

I'm usually the same. However this year I've spent a month (and counting) on a NYE display.

 

I've got 14kg of compositions made up so far, most of them made into comets, stars, gerbs and rockets, but some still needing processing.

 

More compositions on the way...

[psyco_1322]

Non 4th shooting is usually kept to a minimum of a few devices. I usually make up the fact of only shooting a few things by increasing the effect of what I shoot.

[Yankie]

Well I am releived, I made 32 ball shells for new years eve, and I have never made a ball shell in my life, I couldnt test any because it has been too dry to launch anything. Luckily it rained a fuckload so I took some shells to a party. I only got the 45mm ones on film because the camera shit itself. I didn't paste them and used CuO:Al thermite in most of them as a booster. Filled up and fused my big rack together today, around 25 shots of 45mm, 2.5", 3" and 4".

 

Heres the video of the shells:

[swervedriver]

Beautiful Yankie

 

I shot a couple myself tonight. One thing i can say about this hobby is that consistency is not only golden, but a challenge as well. I made some new BP from some pine wood I made chrys stars out of. I like the performance of that comp, so I used the pine to make some meal. I messed up and forgot to clean my ball mill and there was some dextrin still in it from the chrys composition. Anyhow, the BP didn't mill correctly and made one huge hard ball of BP in the mill, I just broke it up like corning it, and thought it would perform satisfactory. Not, lol.

 

Videos speak louder than words, ps- listen to my kids at the end, lol-

 

 

So I figured I'd double the lift amount, and add 2 grams of flash to compensate. That failed too, well, the shell might have looked ok if it went around 300 feet more in the air. Man, the flash made a huge difference in the break size though. This calls for some more experimentation. I'm at 120 feet away from the mortar. You'll see how fast I ran after the break, lol.

 

 

 

I learned a good lesson tonight, not to presume all is good because it was the last time, and test the lift well before using it...

 

.

Edited December 20, 2008 by swervedriver

[Gunzway]

Yeah, definitely if the second shell was higher it would of looked awesome. I always make sure I test my lift before I use it. Whether it would be a dummy shell or just a burn rate test.

Nonetheless, everything looked good except the lift, so at least your timing and shell breaks are good.

[tentacles]

Nice break on the last one, although it looks like a bunch of stars may have blown blind..

 

The thing with lift, is as you identified, consistency. To that end I suggest making several batches, testing them (I like to test as meal-d) and blending them together if your batch to batch consistency isn't very good. I think I've got like 9 pounds of milled BP at home I need to either rice or put on hulls. Ricing I can do, but rolling hulls is not a winter sport!

 

The one thing that really put my BP consistency up was to build a good mill - I'm using an 8" jar with SS media and it rocks! 3lbs of bp in a batch - and I could do more if I put in a full charge of media - in 2-3 hours, from prilled KNO3 and chunks of charcoal.

 

I've decided to make 2kg of Win12 in shimmer mode - this mean subbing Ba nitrate for the Sr carb. Might also make some D1 or other gold glitter. I need to buy some guns bad.. Only got 3" right now, it's killing me when I want to put some 4, 5, 6's into the sky.

Edited December 20, 2008 by tentacles

[Richtee]

I've decided to make 2kg of Win12 in shimmer mode - this mean subbing Ba nitrate for the Sr carb. Might also make some D1 or other gold glitter. I need to buy some guns bad.. Only got 3" right now, it's killing me when I want to put some 4, 5, 6's into the sky.

Hmm I just made some 12yesterday. Very cool stuff...but... isn't the Ba Nitrate in the original? Here's the formula I used:

 

Winokur #12

 

Potassium Nitrate 40

Barium Nitrate 20

Aluminium, atom, spher, 120-325 mesh, 20 micron 14

Sulfur 10

Charcoal Airfloat 10

Dextrin 5

Iron (III) Oxide, red 1

[Mumbles]

I have the one you presented as Win 11.

 

Win 12 is (at least from passfire)

 

KNO3 - 55

Al - 14

C - 11

S - 8

Sb2S3 - 5

Dex - 4

SrCO3 - 3

 

 

 

That was a nice shell break you had. You could possibly even back it down to 1g. Then again it's hard to tell because the break was so low.

 

Don't toss the batch of BP. It seems to work fine for break. You can just put the lift back into the mill to see if it gets better. I bet the BP caked up and became a ball before it was properly milled. This happens to me all the time, I think it's my KNO3 absorbing water. I regularly had to open the mil and break it off the bottom after a few hours to keep it milling properly.

[tentacles]

Rich: that's no Win12 I've ever seen - that formula there is Win11.

 

LOL, mumbles beat me to it!

 

I'll just add that this Win12 formula was also listed in some threads on passfire regarding the shimmering effect when you sub Ba nitrate for the Sr carb - so it's probably the correct formula for 12.

Edited December 20, 2008 by tentacles

[Richtee]

Rich: that's no Win12 I've ever seen - that formula there is Win11.

 

LOL, mumbles beat me to it!

 

I'll just add that this Win12 formula was also listed in some threads on passfire regarding the shimmering effect when you sub Ba nitrate for the Sr carb - so it's probably the correct formula for 12.

 

Well..I copied it from the 40 glitter comps here in the comps section... and that's what I made. I dunno??

Edited December 20, 2008 by Richtee

[Mumbles]

Yeah, I should probably fix that. I have no idea where blindreeper sourced the formulas. I have an actual copy of Pyrotechnica II, so I should fix them, but I'm lazy.

[Richtee]

Yeah, I should probably fix that. I have no idea where blindreeper sourced the formulas. I have an actual copy of Pyrotechnica II, so I should fix them, but I'm lazy.

Well..hell it works well.. "A rose by any other name.." eh? ;{)

[psyco_1322]

Well I am releived, I made 32 ball shells for new years eve, and I have never made a ball shell in my life, I couldnt test any because it has been too dry to launch anything. Luckily it rained a fuckload so I took some shells to a party. I only got the 45mm ones on film because the camera shit itself. I didn't paste them and used CuO:Al thermite in most of them as a booster. Filled up and fused my big rack together today, around 25 shots of 45mm, 2.5", 3" and 4".

 

Heres the video of the shells:

 

What are those bushy simmering stars you used, the ones that you have for rising tails?

[Yankie]

What are those bushy simmering stars you used, the ones that you have for rising tails?

 

They were just a BP+Al comp,

BP - 100

Al - 20

dex - 8

 

1/2" cut stars. I used 200 mesh granular Al, ground tests look pretty cool bacause the silver sparks "dance" in the air and you can hear them flying around.

[Richtee]

Debris management

 

I want to build a couple flying fish shells, and I have some 3" salute cans I want to use.. "upside down" I figger... fusing the bottom and making a cardboard "lid" that's easily popped off, ejecting the primed, lit FF fuse.

 

But I really don't want this 20 gram can coming back down. How do you folks handle such shells? Roll paper cases? This IS a problem with the plastic hemis/cans that is handily avoided by the paper guys. Sigh...maybe I better break down and start pasting.

[Pretty green flame]

If you are worried about the plastic can coming down and hitting something, your best bet is rolling a paper canister, roll your own or use those thin walled spiral wound casings that come with paper caps and discs, a few wraps of pasted paper is all you need to send some FF flying around. Though that plastic canister doesn't really present any significant danger IMO, so I personally would have little worries when shooting in an open area away from cars and other people.