What makes crosettes explode?

[OblivionFall]

Hi there,

 

I was doing some research and looking into various star types as I am getting ready to buy a pump.

 

I saw a video of a test of a crosette star, and I thought ok, cool, it will split into more stars then all of the sudden BANG the crosettes exploded into more stars! I didn't know they actually went bang when they split.

 

I read up on them and it said they utilize a break charge in their "cavity." How powerful of a break charge are we talking here? Would normal BP would? BP with Eckart Al? KNO3 slow flash?

 

Thanks

Edited December 8, 2015 by OblivionFall

[dagabu]

I use 70:30 flash to break them, it takes .75g of good flash to make a nice snappy crossette break.

[wizard7611]

Remember to paste wrap the crossettes! This is a very important step!

[mikeee]

And the answer is..............rapidly expanding gases.

Like Dagabu stated, flash powder is most commonly used, there are other compounds that can also be used.

You want a fast hard breaking composition that will split the crossette and send the segments radiating from the break charge. These are very memorable additions to any shell and add an exclamation point to the shell which gets plenty of attention.

Edited December 8, 2015 by mikeee

[schroedinger]

Or you use a shot in a round cavity.

[memo]

I tried using slow flash in my crossettes, not enough snap. they break but not real good, what else could I use I have no perc.

[nater]

Many people over the years use a dark report mixture of 1:1 potassium chlorate and antimony trisulphide. This is a sensitive mixture. Unless you have experience working with these types if comps, I would leave crosette alone.

[OblivionFall]

Ok well I can't get perchlorate unfortunately

 

So I guess I will just leave crosettes alone

[nater]

Note that I said potassium chlorate. That was not a typo. If you can get that and learn to work with is safely, you are in luck.

 

Due to the small cavity, one needs a powerful mixture that is easily lit to reliably break crosettes. Usually this is standard 70/30 flash or the dark report I mentioned above. Some have successfully used whistle, others use even more powerful types of flash powder.

 

Schroedinger mentioned using shots, these are usually filled with the same mixtures. If the only oxidizer you can get is potassium nitrate, you will probably be disappointed.

Edited December 8, 2015 by nater

[Mumbles]

If you make fairly large crossettes, you can get away with slower bursts. 2-3" crossette comets are about where I'd imagine it'd start working. Nitrate flash with blackhead aluminum might get you a little smaller.

 

I can't believe I'm about to recommend this here, but strontium nitrate based flash is actually pretty brisant. I believe you have some pretty fine MgAl. A 50:50 mixture should probably work for everything but the smallest crossettes.

 

As far as a pump goes, I'd recommend nothing smaller than 3/4". Not many tool makers stock anything smaller than this anymore, but they become a huge pain. They're hard to work with and start to require some rather exotic bursts. 3/4" can be broken with normal flash or whistle after a little bit of dialing in.

[mikeee]

You can always build a chlorate cell and make your own oxidizer.

There are a number of tutorials and videos covering this project.

[Davidg1]

I believe the op is from England. He can get perc and other restricted chemicals if he

became licenced. The equipment needed to produce his own chlorate

and perc is probably beyond his level of expertise and would more likely not work for him.

[OblivionFall]

I believe the op is from England. He can get perc and other restricted chemicals if he

became licenced. The equipment needed to produce his own chlorate

and perc is probably beyond his level of expertise and would more likely not work for him.

I'm in Canada.

[OblivionFall]

If KNO3:Al:S isn't powerful enough for a 3/4" crosette to break it then geez I'm going to need better flash.

What if I used KClO3:Al?

 

The MgAl doesn't work with KNO3:MgAl 1:1. Burns too slowly. Twice as slow as KNO3:Al:S So would it burn faster with strontium nitrate?

 

How dangerous is this strontium nitrate flash? Never heard of anyone using strontium nitrate flash before. How sensitive is it?

I'm just worried that something might go wrong and a 3" shell ends up exploding on me because of chlorate or strontium flash going off in a crosette.

[schroedinger]

Oblivion all your auestions are allready covered in this thread before.

You can also use 1:1 BaSO4 : Mg (at least #200 for 3/4 #400) prusiat/chlorate co-precipate

[OblivionFall]

Oblivion all your auestions are allready covered in this thread before.

You can also use 1:1 BaSO4 : Mg (at least #200 for 3/4 #400) prusiat/chlorate co-precipate

Yes I know I just want to know more info on strontium flash or if it would be safe to use KClO3:Al

 

Would you tell a person that they can use a dangerous comp with reasonable safety but not go over its incompatibilites or instabilities?

[schroedinger]

No i won't but i would advice you to use the search function once, instead of asking for getting spoon feed. Btw. There is also barium nitrate flash on which you can find a lot of information.

[gregh]

Even 3/4" inch crossettes are a pain in the butt. I use round cavity pumps and roll shots. They are very tiny. They make very interesting rising tails on 6" shells!

[calebkessinger]

my whistle seems too hot to break mine.. Something isn't right with your confinement if regular flash wont do the trick.

[gregh]

Yeah, I have seen that whistle in action...

...breaking a 5" lampare shell...

...and my eardrums!!!