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Yankies Flash Stars


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#1 Yankie

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Posted 29 August 2008 - 04:54 AM

Name: Yankie’s flash stars
Composition type: special effect star
Creator: Yankie
Effect: These stars glow orange for a short time before erupting in a bright white ball of light, similar to a camera flash. The larger the star is, the more strobe-like it becomes. These stars are great for those with limited access to chemicals as it uses only the most basic ingredients.

Composition:
KNO3: 40
Aluminum (300 mesh, atomized): 20
Sulfur: 10
Dextrin: 5
Boric acid: 1

Method, Ball mill all the ingredients except the aluminum for no more then 5 minutes, it may ruin the effect if it is milled longer.
Screen the aluminium into the mix using the screen method until the mixture is homogeneous. Now wet the composition with water:alcohol (75:25) (methylated spirits works). The stars can be pumped or cut, but must be bigger than 4mm as they may not work if they are smaller. Cutting the stars is easiest as you can paint a black powder slurry on the top of the slab before breaking it apart, thus only priming one side and allowing a longer delay. If you prime them on all sides the delay is reduced. Priming is not 100% necessary.

Summary, 4mm stars tend to flash 1 or 2 times, 8mm stars will flash 3-4 times and the bigger the stars get the more flashes and more rapidly they will flash.
Heres a video of a 4mm pumped star on the ground:
Here is several 4mm stars in a 2” shell: http://uk.youtube.co...h?v=duV42UxNV7U
And some 8mm stars in a 2” TT shell: http://uk.youtube.co...h?v=RQl3iNOSxvU

Edited by TheSidewinder, 10 December 2008 - 01:45 PM.
User-requested update of information

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#2 Gunzway

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Posted 29 August 2008 - 05:03 AM

I got to say, if these have a the same results in the air they will be great for star mines etc. The best thing about it is, the easiness of making them + the fact that most people have these chemicals. That way people which don't have access to KClO4 etc can have a good effect with just basic chemicals.
Thanks for this fredbert, tomorrow I'll be making a batch and doing a few observations and see what they work good in.

Cheers,

#3 crazyboy25

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Posted 29 August 2008 - 12:40 PM

Cool effect but microstars are well...micro. I doubt the effect will work with larger stars could you please try it make a pumped cut or rolled star about 1/2" diameter with this comp and see if it preforms the same?
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#4 flying fish

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Posted 29 August 2008 - 08:29 PM

I will definetely give this a try. What do you prime them with? I managed to get myself some silicon, but I wonder if the fence post prime might be overkill, or may even destroy the delay effect. After all, isn't the delay probably caused by the fact that the mixture has to build up to the ignition temperature of the aluminum?

Edited by flying fish, 29 August 2008 - 08:42 PM.


#5 crazyboy25

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Posted 29 August 2008 - 10:46 PM

I think hot prime would destroy it. I have seen a similar effect when lighting small piles of copper oxide thermite. It glows brightly then puffs.
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#6 Yankie

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Posted 30 August 2008 - 04:27 AM

quote: "I will definetely give this a try. What do you prime them with?"

They can simply be primed with bp, I just rolled them in meal powder and they light really easily, I doubt they even need a prime.

quote: "Cool effect but microstars are well...micro. I doubt the effect will work with larger stars could you please try it make a pumped cut or rolled star about 1/2" diameter with this comp and see if it preforms the same?"

I have made some larger ones however they are not totally dry, but from what I can see the effect is rather poor, sometimes it doesnt work at all. when I throw them in the fireplace however they are strobe-like. I will test them when theyre dry on monday.
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#7 Yankie

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Posted 01 September 2008 - 04:15 AM

My 60 gram batch of the cores is a dud :( took me hours to press them all
I think I may have milled the mix too long, as the first ones I only used a mortar and pestle.
I tested the large ones and the small ones, the large ones looked pretty good, and even though the small ones didn't work it looked pretty cool with the raining orange dots.

Not quite sure how to attatch video yet.
Attached File  flashy_flashy_stars.wmv   1.73MB   249 downloads

Edited by fredbert, 01 September 2008 - 05:52 AM.

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#8 yellowcard

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Posted 01 September 2008 - 04:28 AM

Seems like a cool star. Do you think this wil also work with 250mesh atomized aluminium ?

#9 Yankie

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Posted 01 September 2008 - 05:51 AM

Seems like a cool star. Do you think this wil also work with 250mesh atomized aluminium ?


I am not sure, but I would think so, you will have to test it.
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#10 mike_au

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Posted 01 September 2008 - 06:14 PM

I pumped a couple of dozen of these yesterday, I tried one this morning and there was no delay it went up instantly with a bright flash :/

Was the one in your first video primed? I primed with meal, I'm wondering if it got too hot too quick.

Even if I can't make them work like yours, they would make nice cores for charcoal stars.

#11 starlight

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Posted 02 September 2008 - 02:26 AM

fredbert should try to lower the percentage of dextrin, try 4%

#12 Yankie

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Posted 02 September 2008 - 04:11 AM

Was the one in your first video primed? I primed with meal, I'm wondering if it got too hot too quick.

I did not prime them, I have made a few dozen today and am waiting for them to dry. I think they need to be milled for a minimum like D1.

fredbert should try to lower the percentage of dextrin, try 4%

I like my stars rock hard, you can try with less dextrin but theres a slight possibility that it could alter the effect.
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#13 Yankie

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Posted 04 September 2008 - 04:28 AM

I have tested these in a 2" shell with some D1 stars and may I say they look terrific.

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#14 Spider

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Posted 07 October 2008 - 12:09 PM

I'm quite impressed, very nice effect and a simple formula. great!
I made a small batch of about 30g today with dark alu. the next smallest aluminium I have is 63µ (about 230mesh), I doubt this will work, but we'll see:D

I hope rolling works as good as pumping does, if someone wants to know, I can tell more tomorrow:)
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#15 Miech

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Posted 07 October 2008 - 04:46 PM

Make sure it is atomized spherical aluminium you are using, flake aluminium will probably give you a sort of silver streamer stars.
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#16 swervedriver

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Posted 29 December 2008 - 12:08 AM

I made some of these today and quick dried in the sun, 4mm pumped using a 1cc syring. I used 400 mesh Al in a small 80g batch to test. I forgot to add boric acid, but a ground test worked anyway. The effect is just as described. 2-3 super bright strobing flashes after approx 2 second glowing delay on the ground.

I rolled them in tigertail. Man, that TT comp was hard to roll for me, maybe because it was a small batch, those are some super ugly stars. They look like black raspberries. Oh well, hopefully i didn't mess the Al in the Flash Star comp up by putting the TT and additional water over them. We'll see.

Anyhow, this composition works! Thanks!

edit: oh forgot to mention, I ball milled it for an hour and a half too. I've since quick dried some flash star cores with the tigertail comp rolled on them, they work great. Shell buildin' time!

Edited by swervedriver, 29 December 2008 - 05:12 PM.


#17 Yankie

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Posted 29 December 2008 - 08:26 PM

edit: oh forgot to mention, I ball milled it for an hour and a half too. I've since quick dried some flash star cores with the tigertail comp rolled on them, they work great. Shell buildin' time!


Well that is pleasing to hear, I said the comp cant be milled too long as after I made a batch that was well milled it none of them worked. Maybe the stars were too small, or I left a chemical out.
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#18 swervedriver

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Posted 30 December 2008 - 09:28 AM

Well that is pleasing to hear, I said the comp cant be milled too long as after I made a batch that was well milled it none of them worked. Maybe the stars were too small, or I left a chemical out.


I found that the flash stars have to be really dry to get the flash. Mine would light, then glow, then just go out if not bone dry. Maybe that could be why?

#19 droppin88

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Posted 14 January 2009 - 12:40 AM

what if I didnt have boric acid? whats the difference if I did or did not?

#20 WarezWally

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Posted 14 January 2009 - 01:30 AM

Boric acid is used to stop the aluminium reacting when wet, its not strictly required.




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