Booster for 2.5" shells

[asdercks]

Hi guys I am building some 2.5" shells and I was wondering what kind of booster and how much of it should i use?, this is not the first time I make this size of shells but the last time I made them I blew some stars blind, so my guess is that I used too much flash, I know the best way to figure how much flash to use will be making lots of shells and use different ammount of flash until I get the results I want, the problem for me is that I live in the city and is not like I can be firing shells everytime I want, so if any of you guys can share some knowledge that can help not to waste so many shells trying to figure out the right ammount of booster to use

 

[nt8]

Don't have too much booster, just not enough good prime (I saw on our club meeting 5" ball shell with 50g perc./Mg booster, all of the 38 comet star was ignited)

 

What kind of shell? Ball or canister? What's your aim with shell? Hard break, symmetric not too hard break, willow style or other effect?

 

I use 70/30 for booster! My opinion, 2-3 g 70/30 must be enough for hard break too in this caliber.

[asdercks]

Don't have too much booster, just not enough good prime (I saw on our club meeting 5" ball shell with 50g perc./Mg booster, all of the 38 comet star was ignited)

 

What kind of shell? Ball or canister? What's your aim with shell? Hard break, symmetric not too hard break, willow style or other effect?

 

I use 70/30 for booster! My opinion, 2-3 g 70/30 must be enough for hard break too in this caliber.

I'll be using ball shells with winokur 20, chrysantemum #6, rubby red emmerald green stars (peony style),I'll also be trying firefly stars and of course I'd like to get a symmetrical break, last time I made them I used 70/30 flash and was using 2-3 gr. of booster, shells had 5 layers of pasting

[pyrojig]

Softer stars need to have softer breaks . One way that may help is use round rolled stars that can take a harder break. Also for a small 2.5 shell You may want to throttle back on the flash. 1-1.5g should be fine with that many layers of pasting . Peony stars can take a harder break, but as stated above , priming is a mandatory step that insures ignition. I step-prime most all my stars( color and or high metal content stars).

Using large amounts of flash in shells is not the best advise, as it adds additional dangers ( especially a 50g flash broke 5" shell) More like a Salute effect , and lucky the comets lit. I like boosting smaller shells with both flash or whistle , but I start out with a smaller amount and build up from there. Pasting more will reduce the need for more flash, and sometimes bp burst will be fine alone .

[asdercks]

Softer stars need to have softer breaks . One way that may help is use round rolled stars that can take a harder break. Also for a small 2.5 shell You may want to throttle back on the flash. 1-1.5g should be fine with that many layers of pasting . Peony stars can take a harder break, but as stated above , priming is a mandatory step that insures ignition. I step-prime most all my stars( color and or high metal content stars).

Using large amounts of flash in shells is not the best advise, as it adds additional dangers ( especially a 50g flash broke 5" shell) More like a Salute effect , and lucky the comets lit. I like boosting smaller shells with both flash or whistle , but I start out with a smaller amount and build up from there. Pasting more will reduce the need for more flash, and sometimes bp burst will be fine alone .

thanks for the reply pyrojig, now that I think about it maybe the issue was the prime, next time I'll add more prime to the stars to see if that was the problem with my previous shells, you mentioned that round tars can take a harder break, but how about pressed stars, can they take harder breaks? I'm pressing all of my stars using a 1/4" plate for colored stars and a 3/8" for all the glitter and tailed stars

[SideGlance]

make one with extra bp prime and one with 1-2 grams of flash booster... test and decide

[pyrojig]

Pressed stars will be in-between. They will take harder breaks than cut stars for the most part, but the shape of round stars will take more abuse (harder breaks) . The binder used will also have a direct relation to the stars strength . Sometimes good ol' dextrin will win the battle for strength and cost. Color stars bound with parlon etc will be very hard too. I screen slice some of my color comp (skylighters method) then roll to round in prime. THis too can be done with the pressed color stars . You want a 2mm layer of hot prime for colors then a 1/2mm finish prime of meal or green mix. WHen rolling round stars you can step prime( with 50% color star comp+50% prime) for the 1st layer of prime if needed( for stubborn high metal stars).

Edited October 25, 2013 by pyrojig

[asdercks]

make one with extra bp prime and one with 1-2 grams of flash booster... test and decide

hey good idea I'll try that

[asdercks]

Pressed stars will be in-between. They will take harder breaks than cut stars for the most part, but the shape of round stars will take more abuse (harder breaks) . The binder used will also have a direct relation to the stars strength . Sometimes good ol' dextrin will win the battle for strength and cost. Color stars bound with parlon etc will be very hard too. I screen slice some of my color comp (skylighters method) then roll to round in prime. THis too can be done with the pressed color stars . You want a 2mm layer of hot prime for colors then a 1/2mm finish prime of meal or green mix. WHen rolling round stars you can step prime( with 50% color star comp+50% prime) for the 1st layer of prime if needed( for stubborn high metal stars).

so what kind of hot prime do you use? I really don't want to use velines hot prime due to the potassium dichromate, I'm using bp+silicon as a hot prime do you think I should use another kind of prime

[Seymour]

In my opinion the dichromate in the veline prime is quite un necessary. Overall the prime is not very different from other hot primes, and you can use any of them in it's place. I'm sure you can get excellent results from simply dropping the dichromate and not replacing it with anything. Ideally you will be priming the hot prime with a BP type prime, so catalysts are not really required, and there are not going to be any reactions occurring that need passivisation with the dichromate in any hobby situation without getting in to Ammonium perchlorate compositions.

 

Standard coloured stars are typically primed with a layer of KClO4, resin, Charcoal, metal (MgAl or or Al typically, but Si is superior) and a binder, dextrin usually. This priming is coated with a final prime of rather average BP with some binder. This should not be fast BP, you want it somewhat slaggy. Often extra charcoal and/por metal is added to this, and often the BP is simply screened together or only lightly milled. Basically like Pyrojig said, though I must admit 2mm sounds like a very thick layer to me. Certainly this will provide reliability, but I'd probably use half that.

 

I've seen very good results with plain BP + Si though, and this 'single step' prime is not uncommon. If you are still having blind stars, perhaps your layer is not thick enough, or your prime is too clean burning. Using lower quality BP helps. For really hard bursts I sometimes like to roll a layer of charcoal streamer over the priming to buy the stars a few moments to slow down, though this ids not so much a necessity as a way to use less expensive chemicals in prime by using a thinner layer.

 

I have to say, considering that the Veline star system are aimed at people who want no fuss, minimal chemicals and essentially little interest in the chemistry/formulation side of things, adding dichromate to the prime is not only un necessary, but runs counter to the whole idea of the composition set.

[Mumbles]

I've heard of some people leaving out the dichromate, or replacing it with another, more benign, transition metal. Think something like iron oxide, copper oxychloride, etc. Basically if it makes a good whistle catalyst, it should make a good burning catalyst. I know it's rather complex, but you really can't argue with success.

[pyrojig]

2mm perch prime( like shimizu's ) is good if your after extreme hard breaks. 1mm(perch prime)is perfect and a finish up of 1/2-1mm hot bp prime of glitter comp is good to slow down the stars to a ignitable speeds .It is all balanced on the burst(hot or light)and the aesthetics one is after . I find that using a glitter as a prime not only functions well, but also adds a nice filler to the initial break, where most stars leave a "black hole " in the break . Using a perch prime is needed for most metal +color stars as the primary prime. Then a hot bp or green mix laced with SI or metal . The need for K-Dichromate is not as critical , but does aid in reducing the energy needed to ignite the perch prime. As stated by the fellows above, it can e subbed out for another just as effective prime.

[asdercks]

In my opinion the dichromate in the veline prime is quite un necessary. Overall the prime is not very different from other hot primes, and you can use any of them in it's place. I'm sure you can get excellent results from simply dropping the dichromate and not replacing it with anything. Ideally you will be priming the hot prime with a BP type prime, so catalysts are not really required, and there are not going to be any reactions occurring that need passivisation with the dichromate in any hobby situation without getting in to Ammonium perchlorate compositions.

 

Standard coloured stars are typically primed with a layer of KClO4, resin, Charcoal, metal (MgAl or or Al typically, but Si is superior) and a binder, dextrin usually. This priming is coated with a final prime of rather average BP with some binder. This should not be fast BP, you want it somewhat slaggy. Often extra charcoal and/por metal is added to this, and often the BP is simply screened together or only lightly milled. Basically like Pyrojig said, though I must admit 2mm sounds like a very thick layer to me. Certainly this will provide reliability, but I'd probably use half that.

 

I've seen very good results with plain BP + Si though, and this 'single step' prime is not uncommon. If you are still having blind stars, perhaps your layer is not thick enough, or your prime is too clean burning. Using lower quality BP helps. For really hard bursts I sometimes like to roll a layer of charcoal streamer over the priming to buy the stars a few moments to slow down, though this ids not so much a necessity as a way to use less expensive chemicals in prime by using a thinner layer.

 

I have to say, considering that the Veline star system are aimed at people who want no fuss, minimal chemicals and essentially little interest in the chemistry/formulation side of things, adding dichromate to the prime is not only un necessary, but runs counter to the whole idea of the composition set.

mmm interesting, I never thought that using fast bp would be an issue next time I'll try some slower bp, also I think you're right about the veline system being aimed at certain people, but can you blame us rookies who don't have a lot of chemistry knowledge for using a system like veline, I can certainly tell you that at this point I've realized that i really love this hobby and that if I want to continue to develop good skills I also need to get some really good literature about the chemistry of fireworks and to practice a lot hahaha..... any books that you recommend