Priming stars

[MadMat]

I still have some nagging problems with partial blind blown stars on a couple of my star comps. I have read about potassium dichromate being a catalyst, but have never seen any prime formulas utilizing it. My most successful priming procedure to date has involved spraying my dried stars with a 2% dextrin solution and rolling the stars in the prime powder (also including a small percentage of dextrin). Presently I used two different prime comp. the first being simple mill dust and the other being a "hot prime"

71 KClO4

14 Charcoal

9 Red gum

5 magnalium

+3 dextrin

+4 silicon/ground glass

I have done single and duplex prime coatings depending on the difficulty of star ignition. My idea now is to add a small percentage of potassium dichromate to the spray solution. My idea behind this is that the dichromate would do the most good at the interface between the star and the prime.

Any opinions on my idea?

[PhoenixRising]

Actually a (now) common recipe uses it: Veline's prime.

 

KClO_{4 - 55}

_{C - 20}

_{Sawdust - 6}

_{Red Iron Oxide - 5}

_{Magnalium - 5}

_{Potassium Dichromate - 5}

_{Dextrin - 4}

 

_{The reasoning behind the sawdust is to create a rough finish that has more surface area and takes fire easier.}

[PhoenixRising]

And another for fun: Perigrin Perchlorate Prime.

KClO₄ - 72

Red Gum - 11

C (airfloat) - 7

Dichromate - 5

Dextrin - 5

 

Here's a good page for some more primes and formulas. http://pyrodata.com/composition/primes

[MadMat]

Duh.... I have this website book marked and have never looked at primes on it!! The Perigrin formula looks like one I might just try out.

 

The ground glass I referred to is blasting media and is 80-120 grit. It's way cheaper than buying silicon at a pyro chem place and seems to work quite well.

Edited May 30, 2016 by MadMat

[lloyd]

You'd be wise to stay away from any "Peregrin" formulae... no matter their purpose.

 

I was - um - VERY close to the development of that book, and wish I could divorce my reputation from it!

 

LLoyd

[PhoenixRising]

That's funny, I don't see any sodium anywhere in the formula.... (Please don't hit me)

[lloyd]

I MIGHT hit you... if I got the joke! (I must be getting old!)

 

Lloyd

[MadMat]

Umm I think he's referring to your disdain for sodium yellows? Anyways, any comments on adding dichromate to a solution for wetting stars before priming them?

[PhoenixRising]

The last post here:

 

http://www.amateurpyro.com/forums/topic/9826-lemon-yellow-stars/?do=findComment&comment=157259

 

I know, it's all tongue in cheek and your dislike of sodium is pertaining to yellow (yella').

 

(darn as I type MadMat beat me to it haha)

[Mumbles]

I'm glad it's working, but you should probably know that silicon and ground glass are not interchangeable and will serve two very different purposes. Silicon is a hot burning fuel, and is particularly good as leaving slag behind. It essentially leaves molten glass behind after it burns. Ground glass is already oxidized, and thus can't burn. It primarily will be providing a rough surface. Sawdust, diatomaceous earth, finely granulated composition, etc. all provide similar roles. I can't really say if they're all equally effective though.

 

In my experience it's not usually the prime formula that causes blind stars. It's usually the thickness of the priming layer itself. Too thin of a layer may not allowed sufficient time to light the star, or will stop burning while the star is still traveling too fast. This is the biggest problem with blue stars which are prone to blowing out, but a lot of stars will exhibit this type of behavior to varying degrees. I would also generally recommend a final layer of BP or green meal over the top of the stars. This usually ensures igntiion. Too smooth of a star/prime surface can be difficult to light. This is not encountered too often though.

[MadMat]

My prime layers are quite thick, especially the duplex coated ones, which is what is on my "problem" stars. The surface is also rather rough (maybe due to the glass in the prime comp.) This is turning into a hair pulling situation with everything I've tried. I do get ignition, it's just that I know not all the stars are lighting. It creates a rather disappointing effect on the particular firework.

[lloyd]

Oh... it took me a while... "stay away from it", then "there's no sodium". WELL! I am OFFENDED! (or not!)

 

There are formulae out there WITHOUT sodium that are to be avoided, also!

 

<G>

Lloyd

[braddsn]

MadMat, when I started pyro, I had problems with blind stars, and I applied all of my energy and research to this 1 problem. Everything else seemed to fall into place, but priming was 'my challenge'. Through hundreds of tests, and taking a lot of great advice, I found the same thing that Mumbles stated above. 'Almost' all problems that I ran into ended up being -not enough prime-. You say your stars have thick prime.... what is "thick"?? Here is what I recommend you try... this works 100% of the time for me: Prime your stars with .5mm monocapa prime first. In the monocapa formula, you can substitute the MgAl with Dark Aluminum. I suggest you do so. Let the monocapa dry. Then, for your final layer, prime with 1mm bp + 5% silicon. Make sure that when you are almost done priming the star, you use very little moisture... you are almost 'dusting' the star. You want a rough outer layer. Now here is something that also helped me.... I cut into the stars as I am priming them to make sure that I actually see the thickness of the primes applied. Don't estimate or guess.... make sure there is .5mm monocapa and 1mm bp. You can even go with 1.5mm bp if you like. Better too much than not enough. Follow these steps, and I bet you get 100% ignition. Once you gain more experience, you can vary your thicknesses and types of primes you use depending on color, and break intensity. 1 more thing..... the star gun. Use a star gun to test stars after they are primed. IF they don't light out of the star gun, you can bet they won't in a shell. Some people claim that there is more heat/containment in a shell that aids in ignition.. while that may be true, in practice I have found the star gun to be the best test for ignition. Hope this helps.

Edited May 31, 2016 by braddsn

[ExplosiveCoek]

Braddsn, do you advice to you milled bp or handmixed/rough bp? Do you put a plug in the star gun? And just random lift charge or overlift on purpose?

 

I'm still struggling with ignition problems too.. I step prime everything, and on top of that finish it of with 1mm meal layer (measured and found true). Still bad ignition. Might be the smooth surface of the stars, the last batches I tried to dust them more in the final steps. Even till the point where they wouldn't pickup anymore meal, so let's hope that will do the trick now.

 

I do always use meal that is slightly milled, quite fast burning already. Now I'm reading this might be bad, either due to not creating slag due because it burns too good or burning of too fast and not propagating the flame. However this would be strange for step primed comps, as the meal is mixed in with the 'original' star comp.

 

Last time I cutted some parlon bound stars (red 2 from Spain), and primed them with meal. Perfect ignition.. However, this mix was only slightly milled, and had some rougher/dusted surface too. I applied the same batch of prime on several other stars. Have some shell's ready to be fired so hopefully this will solve the problem.

 

For now, any insights on this matter are welcome.

[MadMat]

Braddsnm,

I always get good ignition out of a star gun or mine for that matter. I have recently started packing my shells solid with polverone so there are no empty spaces in between the stars and that helped solve all my problems except for one or two star comps. The worst one I have is my parlon bound, metal fueled red stars (I have used both ruby red and independence red as named on this site http://pyrodata.com/composition/filter).

I love the look of these stars but am about to give up on them because of ignition problems.

[braddsn]

ExplosiveCoek: Whether you use ball-milled bp or screen mixed bp for your final prime layer is not really 'super' important, at least in my opinion. Some will disagree. I have tried both, and I personally use ball milled. The bp I prime with is the same quality as all of my other bp... it's hot and fast. I have also primed with screen mixed bp and haven't noticed much difference. The screen mixed obviously burns a little slower, but I break some of my shells VERY hard, and I feel that the ball milled bp performs slightly better if applied in a thick enough layer. BUT this is important: Do you have silicon or diatomaceous earth (5%) in your final bp layer? Try to use one or the other (I use both). Silicon is my favorite. It creates slag that adheres to the star at high speed, and makes a huge difference in my shells. And the way you described your last try at priming, you are certainly doing it right... you should roll the stars in prime until they won't pick up anymore prime, leaving a dry dusty surface.

 

MadMat: There are several reasons that stars can fail to ignite. In your case, my guess is that you need a hot prime to light these comps, followed by a bp layer. I recommend Monocapa prime, .5mm followed by 1mm of bp+silicon. I have yet to find any comps that monocapa won't light (with the exception of some strobe and white flitter comps). It doesn't have to be monocapa though... any 'hot' prime will do. There are a lot of them out there.. pinball, veline super prime, etc. Keep us posted!

[Mixer]

I always double step prime those Red comps to ensure ignition.

[ExplosiveCoek]

Yeah I like those hard breaks, it's exactly what I'm after too.

 

No, most of the time there is no Si or DE in my final prime, only in some of the hot primes (Iuse it as an additive in Pinball prime). I did notice a rougher surface when using not so finely grind meal for the priming, so maybe that already takes over the purpose of DE. But Si shouldn't be necessary as everything is completely step primed, so transitions should be good I think.

 

I did see that my glitter stars (drossy/slag) have a tendency to have better ignition properties than any of my other stars though. So maybe the Si wouldn't be such a bad idea after all. However still I don't get 100% ignition on glitter stars, which is basically meal.. So I guess the last option there would be was my surface was not dusty enough. I'll try to shoot some shell's this weekend, which have the dusty surface priming. So I'll report back to let you know if there was any better performance.

[JOPETES]

'Ignition of stars 100% !! This is the unfinished business of the vast majority, even some professional firework displays.

All advice and said Bradd steps are completely correct. I, in my case I have never used silicon in the black powder and the results are equally valid as the monolayer is very sensitive to the ignition of black powder. If we want an ignition of the stars at 100% even at high speeds (very strong openings aerial shells) must fully respect the thickness of the two layers of primer (0.5 mm monolayer + 1-1.5 of blackpowder) a good bond between the two layers and the star and finally a slightly rough surface, but ............. the key is the use of a good quality charcoal, always a light charcoal, the same which is used for lifting powder, charcoal willow, balsa, poplar, cottonwood etc ... I have said on many occasions in this forum, always use charcoal lighter, not just any coal for high speeds of the star.

Yes, although some do not believe, what happens in the test Stargun is a true reflection of what happens in an aerial shell, not only speak from theory but from practice as well. It is also essential to use a good quality black powder to coat the rice husk or the like has to be a very fast blackpowder in the combustion and must be milled in a ball mill for a few hours. The fire in aerial shell has to spread very quickly and must be retained inside of it, and this is where the game comes in the number of layers of paper used to close the aerial shell.

 

 

[lloyd]

"This is the unfinished business of the vast majority, even some professional firework displays."

---------------------

I'm VERY glad you got your ignition problem solved, but that statement is pure BS! If 'professional fireworks' companies couldn't get their stars to ignite, they'd not be in business! I mean... REALLY!

 

Yeah... we had lots of "issues" getting certain colors and star styles to ignite well -- but they NEVER LEFT THE FACTORY without having been 'solved' 100%.

 

To think that any professional manufacturer would leave such to chance is far beyond ridiculous!

 

Lloyd

[braddsn]

ExplosiveCoek, and Madmat, Jopetes is the guy who taught me most everything I know. What I put in the previous post I must give him credit for. I had ignition issues until I took Jopetes' direction. Lloyd, keep in mind Jopete's english is sometimes sketchy and he may mean something slightly different than what he is saying. I think what he is trying to say is that the vast majority of people in this hobby have issues with prime at one time or another. For me, it certainly was the biggest hurdle. And what he is saying about professional displays, I would agree that it is VERY few and far between, but I have seen a few high end displays where there were a few ignition issues that I picked up on.. affecting the symmetry of the breaks, etc. Nobody is 'perfect' when it comes to ignition (or at least I don't think so). ... don't take him too literal. I think he was just saying that ignition issues are common. Lloyd you sound a lot like a drill seargent! I am going to go out on a limb and say you were in the military at some point in your life? I am ex-military myself... you seem to be very "direct" in your way of addressing things (I wish more people were this way). Am I even close?

[lloyd]

Heh! Yeah... although I try not to let it show THAT much! <G>

 

Yeah... Dad was a career Army officer, and I was in a "special operations" Navy combat unit in Viet Nam.

 

<G>

Jopetes made it sound to me as if he felt professional companies let out products they knew didn't work very well.

 

Some may... (I guess)... but I wished to make clear that OURS certainly never did while I was in the front office! Not knowingly, anyway.

 

Lloyd

[JOPETES]

Hello LLoyd, as you said Bradd only referred me to a very small part of the professional sector, each fireworks factory has its way of applying layers of priming and I have seen at least here in Spain more than a factory of some prestige with system failures priming.

As for the pyrohobby, I sincerely believe that in many cases some want to run before learning to walk, that is, are more concerned searching perfect of colors and not in total ignition first get their stars. As for the public to watch the fireworks,one color a little more green, a little less green, a little more blue, a little less blue star,, what value most in my opinion is that stars light up perfectly and also good symmetry of aerial shells which has a direct relationship with the perfect ignition of stars.

I accept constructive criticism, I like to learn from others.

[lloyd]

"As for the pyrohobby, I sincerely believe that in many cases some want to run before learning to walk, that is, are more concerned searching perfect of colors and not in total ignition first get their stars. As for the public to watch the fireworks,one color a little more green, a little less green, a little more blue, a little less blue star,, what value most in my opinion is that stars light up perfectly and also good symmetry of aerial shells which has a direct relationship with the perfect ignition of stars."

---

And Jopetes, I agree with every word you wrote here! I'm sorry if my prior post was taken as criticism. I am a very exacting worker for the client's good, and sometimes I find offense in things not meant to be taken that way!

 

LLoyd

[asdercks]

You'd be wise to stay away from any "Peregrin" formulae... no matter their purpose.

 

I was - um - VERY close to the development of that book, and wish I could divorce my reputation from it!

 

LLoyd

Lloyd would you care to explain the reason why one should stay away from tom peregrin formulae, I'm just curious Edited June 3, 2016 by asdercks