kingkama Posted February 3, 2019 Share Posted February 3, 2019 I'm trying to use a flash bag for breaking a 70 mm shell, but, also using just 4 grams (that I think not so much) the stars go blind. The stars are primed with 60 30 10 plus 5% silicium 5% black aluminum and all is filled with pulverone. I tried to add more flash but the result was worst. I used rinfasciature technique. Someone have some hint? Thaks Link to comment Share on other sites More sharing options...
dagabu Posted February 3, 2019 Share Posted February 3, 2019 4g of flash is a lot in such a small shell. You may wish to sprinkle it into your burst instead? Link to comment Share on other sites More sharing options...
Mumbles Posted February 3, 2019 Share Posted February 3, 2019 Also,what kind of stars are you using? Link to comment Share on other sites More sharing options...
kingkama Posted February 3, 2019 Author Share Posted February 3, 2019 I will try but I have to say that before I used a nitrate flash 5g, I had good result, I thinked that the power of a standard one was a bit more, but, I understand that the difference between the two is more than 3 time much. Wow scaring thing, unconfined the nitrate one seemed to me better and powerfull... I'm really a newbie... Link to comment Share on other sites More sharing options...
kingkama Posted February 3, 2019 Author Share Posted February 3, 2019 Chlorate and nitrate for red and green, chlorate and carbonate for orange, chlorate, CuO and srno3 for violet, chlorate and CuO for blue (Shimizu - conkling hibrid). Link to comment Share on other sites More sharing options...
Arthur Posted February 4, 2019 Share Posted February 4, 2019 The purpose of a break charge is to light all the stars before pushing them outwards. If you over boost the break then there is a risk that some to all of the stars will not light before they travel outwards.Your nitrate boost was slower than your flash boost, try reducing the boost even more, the stars must light before they spread out. Builders of big cylinder shells use a weak break powder with rice hulls or similar diluents. Just a few times you want the break to start at the centre of the shell so you need to pipe the fuse fire to the centre in a cardboard tube and fit it with a flash bag in the centre but containing a very small amount of slow flash, say 0.1g of flash. Link to comment Share on other sites More sharing options...
wildcherryxoxo Posted February 5, 2019 Share Posted February 5, 2019 Arthur, Who is building large cyliders, with rice hull diluted powder? Link to comment Share on other sites More sharing options...
MadMat Posted February 14, 2019 Share Posted February 14, 2019 A few thoughts on your problem. I don't know how much experience or knowledge you have so please, don't take offense if anything I say is too basic for you. Poor containment (insufficient pasting/spiking or even poor quality paper) can cause poor breaks and bad ignition of the stars. The stars are simply flung out into the air before getting a chance to light. So then, you try boosting your break more to make up for the poor break caused by bad containment and just make star ignition even worse. I say all this because I agree with Dagabu; 4 grams of flash in the size of shell you described is an awful lot, which makes me think your experiencing exactly what I just described. In any case, even well made shells that are hard breaking shells always present a challenge to get 100% ignition of the stars and I believe every pyro goes through this problem early on, I know I sure did. Among other things, my best solution blind blown stars was a double layer prime. My first layer is a perchlorate based prime with aluminum and silicon. I then add a layer of finely granulated BP. Yes, finely granulated as it creates a rough surface that takes fire much easier. Good luck! Link to comment Share on other sites More sharing options...
kingkama Posted February 15, 2019 Author Share Posted February 15, 2019 (edited) I found that my problem was a mix of all of you reported. Obviously no offence taken, I like to write here to be criticized then learn from that. I reinforced the priming using 69 21 10 mix (that I use for black matches) applied as slurry than covered in the same dusty mix plus 8% Si and 5% black aluminum, reduced the flash bag to 1 gram of 70/30 or 3 grams of Allen report 6, used 2 string of hemp twine(rubbed in wax) for spiking the 12 vertical and half in the rinfasciature, used a hot pulverone fine granulated for filling the space between stars and the flash bag/spolette assembly, I built two shell for my birthday they worked pretty good. I started to experiment with standard flash to add a little of booming sound, because my old version (slow nitrate) sounds me too weak, obviously I will continue to experiment to obtain a better and homogeneous result, thanks to all and if there is some other hint I will be happy to read it. I have no access to perchlorate at the moment, but when I can I will try the double layers, also my stars are all pressed or cutted to forming a color inner core to the shells, so next step is to build a stars roller. Also I discovered that the craft I was using was a recycled one that I found really weak and substituted with a first quality one. Edited February 15, 2019 by kingkama Link to comment Share on other sites More sharing options...
braddsn Posted February 21, 2019 Share Posted February 21, 2019 Kingkama, try and double the amount of prime you are currently using. In my experience, not enough prime is often the problem. You will know when you are using too much flash when your stars break into pieces. I can use 5g of 70/30 in a 3" shell and get 100% ignition. Link to comment Share on other sites More sharing options...
dntmi Posted April 30, 2019 Share Posted April 30, 2019 Following Link to comment Share on other sites More sharing options...
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