For those using scratch mix for prime...

[braddsn]

I am just starting this post for a 'discussion'... and like everything else in pyro, all of our bp's are a little different, charcoals a little different, methods different, a lot of variables..but this is something I noticed during the last 2 shell testing sessions I had. I use the 2-step KP hot prime system.. which consists of a layer of KP hot prime rolled onto the star, then a final layer of bp+mgal. My final bp layer was "scratch mixed" instead of lift quality. I fired 4 shells. I noticed that throughout about the first half of the stars trajectory I had some orange fallout. It took away from the clean color that I was looking for. It took me a fair bit of time to figure it out, but after watching the video in slow motion I noticed that the fallout was caused by the scratch mix bp burning so slow.. So I primed the next batch of stars with lift quality bp+mgal for the final layer, and the fallout was completely gone. Plus, in watching the video in slow-mo, the color "turns on" much quicker. I know this is nit-picking.. and most ppl probably don't care.. lol. But I figured I would throw it out there. I am starting to think that if your chems are screened/mixed correctly, and your prime is rolled on in the right amounts, then "scratch prime" is not needed. Lift quality bp prime is snappier and gets the job done "cleaner" if you will. Yes, I am becoming a pyro-geek. What is wrong with me? Cheers!!

[enanthate]

How much prime do you add, KP and BP? And when people say 1mm for example, is this 1mm layer or 1mm total growth in diameter (i.e 0.5mm layer)?

 

Sorry, had to ask about this, had some ignition issues that almost made me depressed lately! Even my TT stars had a 10% ignition rate the other day, and I was firing 7 shells without any booster, pasted with 12+ layers. Something is wrong, and I suspect I'm not adding enough prime. I've been adding about a 0.5mm layer of monocapa, little bit of BP/monocapa step, then 0.5mm BP. Maybe even less. Is this not enough?

This was for colors obviously, the TT/any charcoalstars wasn't primed at all.

[braddsn]

Ok this is my experience so far with prime enanthate... I was also having some ignition issues, but now I believe I have solved them. First, I was just trying to (estimate)and add about 1mm of prime to my stars, and that was a mistake. Trying to estimate amounts of prime is a bad way to go about it, the results vary too much. So, take the amount of star comp that you are using, and you will need to prime 30% by weight. So in my case, I use a 2 step prime system. Thus I split it.. 15% kp hot prime followed by 15% bp+mgal. So for example, if I roll a batch of stars using 1kg comp, I will use 300g prime total.. 150g KP and 150g bp+mgal. I personally have not used Monacopa, but I do remember reading good things about it. IF you are using 30% and still having issues, I suspect maybe you are not screen mixing your comp well enough, or maybe not mixing your prime properly. Now for the next subject, charcoal stars. I have recently discovered something interesting. IF I use my homemade charcoal (Eastern Red Cedar) for my charcoal stars, they don't need primed because they light without it. BUT, if I use commercial air float charcoal, they must be primed. The type of charcoal varies from person to person, so my final decision is simple... PRIME EVERYTHING. Prime your charcoal stars just as you would any other stars. This will accomplish 2 things. 1) It will ensure that your stars light regardless of charcoal type, and 2) It will provide a more uniform ignition. I have noticed that when charcoal stars don't have uniform ignition, they can sort of act like 'go getters'... some of them will fly in odd directions during a break. Good priming can eliminate 'some' of this. Hope this helps you. Oh and, like I said above.. .I have found that it is imperative that you screen mix your chems properly. I now screen mix with a 60 mesh screen.. and there is alot of parlon and red gum that doesn't make it through the screen. Also there is a fair bit of charcoal that doesn't make it either. These "chunks" have an effect on how your stars look, and how they light. Before about 2 weeks ago, I just screened through a kitchen sieve. Now that I am screening properly, I have noticed a big difference in how pure my colors are, and how they light. Hope this helps ya. Good luck!

[rogeryermaw]

thank you for sharing your findings. this is solid gold! got me scratching my head wondering about those strobes that blew blind on me...i know stars are not exposed to flame as long when breaking from a shell as they are fired from a test gun, but wondering what else i could have done to get them going...

Edited February 12, 2015 by rogeryermaw

[braddsn]

Roger, did your stars blow blind from a test gun or from a shell? I believe that there has to be just enough prime to burn while the stars are going warp speed. If your prime goes out while they are going too fast... they will just blow out. On another note, i sometimes have trouble getting stars to light out of a test gun no matter what i do. I think the containment from a pasted shell can actually help ignition. With a star gun of course there is no containment. I dunno... im constantly tryin to chase down what works best. Roger I think we will eventually be makin Japanese quality shells. Just might take a while.

[pyrojig]

Rodger : I think that Braddsn nailed it . Sufficient prime is key .Also the particle size of the metal in the strobe is a factor. To big and the stars are never gonna light. I had this issue, one cure is mix mesh to aid in ignition , if going for larger metal in strobes. I took another approach for the strobes ignition , because I was breaking my shells very hard, I rolled the primed stars ( that wernt lighting ) in glitter. It made a HUGE diff. and the stars lit( had time to slow in flight) , and gave a wonderful full break in the center of the burst.

Edited February 13, 2015 by pyrojig

[schroedinger]

Also one thing i can just recommend is to use silicone and/or barium coumpounds in a prime for hard to light stars. They both result in a lot of dross sticking to the star.

[enanthate]

First of all, thanks brad, your post is helpful indeed. Will start weighing out my primes, and get a new feel for it.

 

I finally figured it out yesterday. My problem all along has been, believe it or not, rice hulls. I like to really compress my shells real hard when building them. I've been creating "fireblocks" in every single shell I've made. The primes were rarely the real issue.

Throwing my rice hulls away, will never use that crap again. New era of optimism, hope and awesome videos to come!

Edited February 13, 2015 by enanthate

[Mumbles]

Why would you want to use silicone in a prime? It's already mostly oxidized.

[FlaMtnBkr]

Isn't silicon used in prime fairly often? I know I've used it and assumed it was helping. Do you know something we don't or just picking on the incorrect spelling?

[Carbon796]

First of all, thanks brad, your post is helpful indeed. Will start weighing out my primes, and get a new feel for it.

 

I finally figured it out yesterday. My problem all along has been, believe it or not, rice hulls. I like to really compress my shells real hard when building them. I've been creating "fireblocks" in every single shell I've made. The primes were rarely the real issue.

Throwing my rice hulls away, will never use that crap again. New era of optimism, hope and awesome videos to come!

Did you coat your rice hulls in BP ?

[schroedinger]

Why would you want to use silicon in a prime? It's already mostly oxidized.

Thats the wrong stuff. You need to silicone the metall. This will result in molten glass sticking to the star. This way you get good ignition since heat can be transferred by contact and not only by radiation and for a prelonged time.

Edited February 14, 2015 by schroedinger

[rogeryermaw]

i mixed the comp, cut with n/c and flattened it out to about 1/4". my prime is typically two stages: first is kp- kp 70, c 20, si 5 and gum 5. second is to wet with thin n/c and roll in b.p.

 

this has generally worked on every formula i have made. the combined layers of prime ususally builds up to about 1/16" leaving most color stars about 5/16"-3/8" or so when finished.

 

they light perfectly out of the star gun even fired hard, but failed in a 4 inch shell, unboosted. i don't typically use rice hulls so may be breaking too hard. i have been wrapping my shells to fit the mortar so i don't get low breaks...perhaps one or two less layers?

Edited February 13, 2015 by rogeryermaw

[braddsn]

Schroedinger, Mumbles was referring to the fact that you said "silicone", a completely different substance than "silicon". hehe. I do use silicone, but usually to seal around my windows. Schroedinger, I do in fact incorporate both silicon and diatomaceous earth in my bp+mgal final prime mix. Roger, if anything, I usually find it harder to light stars out of a star gun than in a shell. I suspect it's because in a shell that is pasted many times, the stars are exposed to a little higher temperature for a longer duration before they are thrown away from the shell...whereas in my star gun, there is no resistance. I am curious as to why you are not using rice hulls?? I am trying to figure out what might be amiss for your stars not to light. You are too methodical to have left something out... so it has to be something tricky...like maybe the fact that you are not using hulls. Also for what it's worth, I found on 4" shells that pasting 6-8 times seems to be the sweet spot. I think any more than 8 layers on a 4 is a waste of time. Plus, with my 4's, at 8 layers they are fairly snug in the gun... no clearance and slide slowly to the bottom. I don't think pasting is your issue, personally. I would try meal coated rice hulls at 5:1 or 7:1 and see how it goes. I have a feeling they will light. I do want to know what your thinking is about not using rice hulls. For the longest time I wondered why rice hulls were used, and not just granulated bp. But I finally just decided that there has to be a good reason (besides rice hulls are very available to the oriental folk.. lol). They are the #1 carrier used in shells worldwide, and I assume there has to be a reason for that. In my shells up to this point, I have found that MCRH 7:1 with NO booster is the sweet spot for me. Booster made my shells break much harder, but it blew blind stars frequently, and took something away from the beauty of the shell. Hard to explain. Thus, I am not a fan of booster. Instead, with solid pasting and powerful bp, I have been able to achieve the breaks I want. I hope to have some videos up soon of some more shells. I have been rolling stars like a madman! Good luck pal! Keep me posted!

[schroedinger]

Ok that explains the fault. I will edit it.

Braddsn rice hulls are used to safe weight and cut down the strenght of the break. Pure granulated bp is much heavier then MCRH. Specially if you go bigger then 4" you will see the difference increasing. A 6" would use about 3 to 4 pounds of 2 FA. But all you really need is 1/2 to 3/4 pound of bp.

 

Also imagin a break of 3 pound bp in a 6" many stars would propably shatter or stay dark, since the burst would be way to strong.

Edited February 14, 2015 by schroedinger

[enanthate]

Using hulls in larger shells is not ideal, unless its a double petal or something similar. A large shell with only a normal row of stars will typically be too big for hulls, creating a fireblock. Flame propagation is highly limited, and the shell might break without igniting stars.

Much more on this on passfire.com.

[Mumbles]

I've seen a 6" shell broken with just 2FA. They don't really break any harder than a similar shell with BP on a carrier. I suspect they both rupture at the same internal pressure, and the excess BP remaining from the 2FA just burns away in the atmosphere.

 

I don't know if I entirely believe the fire block arguments that Kyle has made. If made right, the hulls are fairly robust. Other carriers are available as well.

[enanthate]

In my situation im 99% sure, because of the ring and bowtie example among others. Maybe I havent been making it right, like you suggest.

I had a batch with relatively wet bp on hulls, which dried to become more like hard pellets than soft hulls. This worked well.

Most of my batches have been soft, dry hulls. Give this enough compression in a 4" and youre asking for trouble. BP's burnspeed is probably relative to this subject. I've been using same quality powders as I lift with, which is fairly hot (10% takes them too high).

Edited February 15, 2015 by enanthate

[braddsn]

Enanthate, I would do more experimenting with MCRH. I would highly suggest you not throw them away. There is a reason that almost every shell you have ever seen break has been loaded with them. I have zero experience with anything beyond a 6" shell, but I can tell you that coated hulls perform perfectly on 3, 4, 5, and 6" shells. I have also seen many videos of bigger shells being loaded with coated rice hulls. The flame block argument is not working out in my head. Fact is, the hulls provide pretty large (relatively) areas where flame propagation can take place. One thing I have learned in pyro so far for sure, is that when a 'tried and true' method of doing something is not working for me, it is usually my fault. I have had stars blow to pieces because they weren't dry yet. I have had lift powder perform very poorly, because it wasn't dry yet. I have had stars blow blind, because I didn't prime them enough. The list goes one. MCRH is tried and true as much as black powder. Keep working on it. Make sure your burst is COMPLETELY dry, then dry it AGAIN. And go for a 7:1 ratio. I think you will be surprised. Done right with proper pasting, and you won't need to boost anything.

[enanthate]

Maybe you're right. Are you members on PF though? Have you read the article? It really makes sense in it.

Got a batch cereal ready, will try that. I hope you guys are wrong!

[schroedinger]

Yes the passfire article sounds very reasonable, and I'm sure it is right, but the fore block mentioned will need some really high forces to work. I don't know how many hulls you used, but did you try to used only that much hulls that your shell has only a 1/2" gap between hemis before compressing the two shells together?

 

Also have a trie with puffed rice as a carrier. 4:1 BP on puffed rice works perfect.

Edited February 15, 2015 by schroedinger

[braddsn]

Enanthate, for what it's worth, you are not the only one having problems with rings, bowties, etc... LOL. I made a ring shell about a week ago...good primed stars, easy to light comp (red), shell pasted 8 layers.. everything done right.... and ONE SINGLE STAR lit... LOL!!!! Obviously, I built it wrong. I glued a ring of stars around one rim of a hemi and it didn't work. Then I started reading more about ring shells, and there are better ways to build one. I have a lot to learn.

No I am not a member on PF. This is the only forum that I am a member on. I tend to rely heavily on the word of people that have experience, and success. Mumbles (a master shell builder/chemist), Xtreme Pyro (shoots professional pyro shows), Jessoman (very experienced pyro) and Seymour (rolls stars for a living), those are just 4 examples of guys that I can think of that will say rice hulls work! They have always steered me right and there is always continuity in their advice. (I don't mean to speak for them, but if you ask em they will all say rice hulls work). Thus, if hulls are not working for me, it must be something that I am doing wrong. I have found numerous articles on the 'internet' that were dead wrong. Initially I was putting 12mm color stars in 4" shells, because an article I found said to. Then XP told me that they should be more like 6-7mm. LOL.... I downsized and now I am not starting fires all over my property. You will figure it out I am sure. I still have little problems left and right.. still have a long way to go. But that's the fun of it, right? Cheers!

[MrB]

I have found numerous articles on the 'internet' that were dead wrong. Initially I was putting 12mm color stars in 4" shells, because an article I found said to. Then XP told me that they should be more like 6-7mm. LOL.... I downsized and now I am not starting fires all over my property.

Star size is always down to the effect your creating. Really fast burning stuff with high hard breaks can be large, slower burning, lower breaks, and they have to be smaller. Swatting fireflies might be one thing, but when your fireflies actually set shit on fire, i agree, thats a problem ;- )

 

B!

[braddsn]

Roger, (and others that may be interested), I had a discussion with Mumbles.. and I am going to try something that may really help eliminate any blind stars. We shall see. I am going to roll my stars in a very fine granulated bp on top of my final prime layer. Whenever I blow a blind star, it's always because the prime doesn't light. I think the rough layer on the outside caused by the small granules of bp may be the solution. I will keep you posted.

[nt8]

Roger, (and others that may be interested), I had a discussion with Mumbles.. and I am going to try something that may really help eliminate any blind stars. We shall see. I am going to roll my stars in a very fine granulated bp on top of my final prime layer. Whenever I blow a blind star, it's always because the prime doesn't light. I think the rough layer on the outside caused by the small granules of bp may be the solution. I will keep you posted.

I agree with you&Mumbles! What I wrote in the aqua topic, for me this mean the "scrapy" prime surface. I have used in the past a very fine granulated bp in the final prime layer. i use the method of my clubmate now, make fuzzy, scrappy surface. Our club like the hard brake, and the blowblind is very rare. (Sorry for my bad english...)

Edited February 16, 2015 by nt8