Which star prime is used on commercial stars?

[redbullzuiper]

Im trying to figure out which star prime is used in commercial fireworks, like small cakes.

 

Just curious, because here in the Netherlands they use 2G of flash powder, inside the mortar, and all stars are igniting. I didnt succeed with my usual BP + Silicon prime.

Im trying to make my own cake, but ended up with salutes. Because the stars didnt ingnite. I used 2g of flash 7/3 KClO4/Ai.

 

I dont have a picture of the stars, and can't find them either. But what I do know is that the stars are looking lightgray. So the prime isn't black powder.

 

Anyone knows which prime is used?

Edited October 29, 2017 by redbullzuiper

[Mumbles]

It's going to depend on your stars too. Some have poor critical wind velocity. The best prime on earth wont solve that issue.

 

I've heard that using phenolic resin instead of other things like red gum can improve ignition. This would be applicable for something like pinball prime or monocapa. Another thing that can work is using a formula like C6 or spider stars instead of BP. These stars are designed to be broken hard, require no prime, and often light from primarily flash breaks. The higher charcoal helps it stay lit at high speeds to an extent.

 

The other thing you may want to think about is using BP or polverone in with the flash burst. That's how the chinese cakes and cylinder shells are made. They're practically pressed solid. BP increases the amount of gas produced and helps with ignition. Flash on it's own isn't a great burst.

[Arthur]

Prime needs to be a relatively slow comp. You can fire BP on a sheet of paper with no scorching, but prime will set light to the paper. Flash is a poor powder to use -it's too fastthe flame front can pass by before passing ignition. Lift with good BP, prime with screen mixed ingredient BP, maybe add 5% Silicon dust to the prime.

[redbullzuiper]

Thanks @mumbles. I will try this pinball prime. I like the idea of C6 as prime too, then you have some kind of multi-star.

 

I tried to break the cake with pulverone, they light indeed. But the break was really soft and small. The cakes are pretty small, so I think BP pulver isn't really fitting.

 

@arthur I tried BP + Si, but they were not lighting when using 2g flash burst.

[Arthur]

Screened BP ingredients (NOT milled) with added silicon makes a better prime for most things unless they are sulphur sensitive.

[Mumbles]

I go back and forth on that Arthur. There's reasonable explanations on both sides. On one hand screen mixed BP burns slower, and leaves more slag on the surface. This means more residue and more residence time to light a star. On the other hand, milled BP will quickly light the entire surface, probably be more ignitable due to a more intimate mixture, and burns hotter.

[RichardH08]

I have to agree with Mumbles - the more I look into this kind of question, the more I find that the answers aren't at all simple. I've recently been looking at one or two of the so-called 'hot' primes and have found that they don't burn anything like as hot as you might think. It seems that they owe their effectiveness to a relatively slow, slag-creating burn that efficiently transfers heat to the underlying composition. But there are also primes - like pinball - that appear to be more successful than you might expect from simple considerations of how fast and how hot they burn. It seems clear to me that other factors come into play, but I don't know what they might be.

[Carbon796]

Have you compared the flash comp you are using to their's ?

[redbullzuiper]

What I know for sure is that they use KClO4/Ai. Don't know the ratio. Ive once opened a cake to see whats inside and lighted the flash. It burned, as far as I remember, as fast as the flash I am using.

[Pyroboy]

I dont think they are using straight 70/30 KClO4/ dark Al Flash. Its way to strong, so maybe try some softer flash. I had succes with either 50/50 KClO4/ dark Al or 50/25/25 KClO4/Al/MgAl (65µm) or use some bariumnitrate flash.

It could also be that your stars are destryed by the force of the flash. Are you shure they just blew blind?

[braddsn]

Redbull, in all of the pain-staking testing I have done over the past few years, I agree with what Mumbles posted. First, for the prime used in cakes, if you will notice, the large majority of stars that are found in cakes are usually some kind of charcoal or metal streamer, that changes into a color star. They are killing 2 birds with 1 stone. It makes a pretty effect, and charcoal comps (eg C6) make fail proof primes. They light easily, and will keep burning at super high speeds. They are perfect for a color changing star. On the other hand, when you want to prime a plain color star, like a red star, things change a little. If you don't have a streamer like C6 for prime, you have to have a reliable prime that lights easily, lights quickly, and burns hot. The Chinese use a single layer of prime on their stars. I don't think they will ever let all of their secrets out, but I do know it is basically bp, but instead of using straight KNO3, it is around a 50/50 mix of KNO3 and KCLO4. They also add silicon and phenolic resin I believe. I am sure there are more 'secret' ingredients, but that is the basis. I do believe that when breaking a color shell hard, using a ball milled prime helps. There is debate about this, but a ball milled prime will certainly light the whole star quicker than a screen mixed one will. But this factor doesn't really come into play until you start breaking shells extremely hard. Also, like Mumbles said above, and probably the MOST important part, is using phenolic resin in both your star comp and in your prime. I am breaking shells very hard now and getting 100% ignition using only a .5mm layer of monocapa prime. I was never able to do that before when I was using red gum. Half of my stars would blow blind with monocapa only as prime. Now that the stars are made and bound with phenolic, and the monocapa also contains and is bound with phenolic, everything has changed for me. The Chinese use phenolic resin in their stars, and that is why. If you want to break shells like the Chinese do, phenolic is critical, in my opinion. Good luck!

[redbullzuiper]

Thanks @braddsn for sharing your finds. Ive heard and read alot of promising info about phenolic resin. Especcialy when redgum in quantity's bigger then 10% is used in stars, it can be replaced be phenlic resin.

 

So I ordered it a few weeks ago. Will get it this week I think. Im going to try it out as soon as I get the phenolic resin.

 

I indeed like color changing streamers. But some colors are prettier without it. Like a cake with orange and blue stars. I really like that combo

 

Anways, thanks for all the info.

[Yus]

braddsn said a truth. Recently, I have conducted a small experiment by using laboratory XRD diffractometer and established composition of chinese star prime /not only/. Indeed, it consists of crystalline KClO4, KNO3, AlMg alloy, sulfur and, probably, charcoal and binder - phenolic resin /it has black color and smells like phenol/.

Edited November 7, 2017 by Yus

[redbullzuiper]

I made a batch of Veline's blue star composition with C6 as prime. It works really well.

 

Here a video where I test it in a star mine.

 

https://www.youtube.com/watch?v=V_B_giWj4tY

[braddsn]

Looks perfect redbull! C6 is a very effective prime, and will stay lit in even the hardest breaks. You can add a little titanium (5-10%) to the C6 to give a sparking/twinkling effect.

[redbullzuiper]

I only have course titanium (Ti flakes 0 - 500um). I though it will be difficult to role stars with such course Ti in it.

 

Or is this not true? Never tried it.

[Mraliksr]

 

braddsn said a truth. Recently, I have conducted a small experiment by using laboratory XRD diffractometer and established composition of chinese star prime /not only/. Indeed, it consists of crystalline KClO4, KNO3, AlMg alloy, sulfur and, probably, charcoal and binder - phenolic resin /it has black color and smells like phenol/.

Greeting Sir,

I am also trying to make 25 shot cake everything all right but my small shell burst and stars not get ignition, I have used hot prime but strars not get ignition completely.

while chinese all shell explode with complete igition and all stars burns. Me need guidence and infromation.

I only have course titanium (Ti flakes 0 - 500um). I though it will be difficult to role stars with such course Ti in it.

 

Or is this not true? Never tried it.