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First 4" shell


Tourbillon

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First 4" shell. Stars didn't ignite properly but overall it functioned correctly! I'm calling it a success.

Edited by Tourbillon
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Good job, Tourbillon! Thanks for posting video too.
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Thanks guys,

I'm assuming the poor ignition was due to the prime. It was just a BP layer. I have another batch of stars I'm possessing, this time I think I'm going to incrementally step prime from color comp to pinball to BP.

 

Any thoughts? I would like to find a prime that I can make using on hand chemicals to avoid shipping on only a few things. On hand would include most of the chemicals for shimizu low temperature color compositions, dark aluminum, and BP chemicals.

Edited by Tourbillon
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A couple percent dark Al would heat that bp up. I'd do a layer with that and a somewhat thick layer of screen mix over that to give the stars some time to slow down after the break before they burn down to the color comp. Decent break and symmetry though. Good job! Thanks for uploading!

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Thank you for the ideas. I have spent the day researching pinball prime and noticed some listed dark aluminum as an enhancer to help it trasfer. I'll do some experiments with pinball and bp prime enhanced with dark Al and report back!
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If you have a color that is hard to light i can recommend to use 75% color mix and 25% BP then a mix of 50/50 followed by a mix of 25% color mix and 75% BP and finally 100% plain BP.

 

Great job whit your shell!

 

Regards

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I decided to try priming with 4 steps 25%bp green mix, 50%, 75%, 100%, then dusted with some bp mill dust so it looks like a chocolate truffle (fluffy dusty coating). I'll start a new thread in the newbie section when this shell is done, with my future projects and troubleshooting. Thanks for the help!
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Tourbillon.

I'm only making canister 2.5 shells. So not that big deal, BUT, the first batch of shells had poor ignition.

The second batch had a ignition of 100 % (or so, didn't count the ignited stars vs the real number of stars in the shells).

it was just miraculous to me :-)

 

The prime I used was:

- BP (wine charcoal, ball miled)

- additional Silicium metal powder (can't remember the percentage, the mesh size, but few: I can send you the information if you want, once back home, and reading my sticker on the star prime container)

- additional KNO3 (SAME as above)

 

This was just the very last layer, the stars themselves were first primed with monocapa when using Jopetes stars, or with Veline prime when using Veline system.

For all the other stars (chrysanthemum, Zinc granite and basically the KNO3 based stars etc.) just the BP+Si made the job!

 

Additional info: my break charge was just Willow green mix coated ricehulls, no booster ( a nice pak!, and not a loud blam!). Sometimes it is also known that a too hard break creates such a high velocity for the stars, that ignition gets a hard matter.

Edited by Sulphurstan
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I use pinball with 6 percent dark aluminum and 6 percent silicon. I then step prime color and pinball in 3 steps 25:75 pinball to color then 50:50 then 75:25 pinball to color then finish off with hand mixed bp. Some may say it is a bit overkill but I had star ignition problems when I started out and I haven't had any ignition problems since I started priming this way. Hope this helps you out some Tourbillion.

Adam

Edited by clarkie752
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Something to consider is that BP mill dust may not be optimal for priming. A trick is to roll a thin layer of charcoal streamer composition on the outside of the star. These compositions tend to have good ignitability and importantly good wind resistance. The charcoal embers smolder and retain fire on the surface of the star. Star velocity is highest immediately after the break so the outer streamer layer allows the star to slow down a bit before ignition of the primary color. Step priming with three or four steps seems very impractical.

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I was recently talking with a friend about this very thing. Starting to prime my stars with a fast burning streamer, like C6. It's almost the same formula I use for spider web stars and shells. If it will take and hold fire from a flash bag, anything will light it. Bill Ofca once mentioned the same thing. One of his prime formulas is again very close to C6.

 

I will say that when rolling or priming with a toro like method, step priming is actually pretty simple. As long as stars are lighting, that's the important part. An important part I've often struggled with actually.

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I will say that when rolling or priming with a toro like method, step priming is actually pretty simple. As long as stars are lighting, that's the important part. An important part I've often struggled with actually.

 

So many lessons learned from so many blind stars. And barely scratching the surface.

 

Wonder if glitters make prime as good as C6? Lots of sulfur for a good slaggy covering should help.

Edited by rogeryermaw
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Glitters do work good for ignition but they will coat the stars with slag and wash out colors. Ask me how I know.
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So many things to try. I'm waiting for my burst and stars to cure. I'll probably start a new shell this weekend so it will be a couple weeks before my next test. If the bp step priming doesn't work it's on to the next method.

 

And I am rolling my stars so step priming just requires the extra task of planning out and measuring the ratio of the steps.

 

In the meantime you've given me lots of info to digest :).

Edited by Tourbillon
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So many lessons learned from so many blind stars. And barely scratching the surface.

 

Wonder if glitters make prime as good as C6? Lots of sulfur for a good slaggy covering should help.

 

 

Glitters do work good for ignition but they will coat the stars with slag and wash out colors. Ask me how I know.

 

 

If you choose the right glitter, it works great.

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If you choose the right glitter, it works great.

 

Yeah that is true, it all depends on what the delay mechanism is. I had to make my color stars quite large in order to burn of the W20 slag, even then they only displayed their true color just before burnout. A Winokur glitter with sulfer and RIO should work good, or one which uses coarse MgAl for the delayed flashes.

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I probably should have been more specific. Personally, I'd pick a relatively clean burning glitter actually. They're all going to leave plenty of molten material and slag behind. This generally entails keeping the elemental sulfur content down. Look for something in the 10% range, not the 17-20% range. This usually correlates with the use of antimony trisulfide, not not always. Antimony would only help primes. We're also often talking about colors here, so I'd avoid anything with sodium, or at least a lot of sodium in it. They're not perfect, but something like Winokur 30, or 31-38 might be good choices.

 

Also something like Williams No-Antimony glitter.

Williams No-Antimony Glitter
- 55 Potassium nitrate
- 17 Airfloat charcoal
- 7 Sulfur
- 4 Red iron oxide
- 10 Aluminum 12 micron spherical
- 3 Magnalium 100-200 mesh
- 4 Dextrin
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