AdmiralDonSnider Posted July 10, 2010 Posted July 10, 2010 Yesterday I experienced what I consider to be one of those annoying inconsistencies a pyro has to stand from time to time. I shot rolled D1 stars from my stargun to evaluate their performance before using them in aerial shells. To my surprise they didn´t behave as desired: a few meters they seemed to glitter quite well but then the "drops" (the molten mass responsible for the effect) stopped ejecting spritzels and came down all the way back to the ground without anymore twinkle. I have never seen such a strange behaviour; what irritates me the most is that I´m pretty clueless about the reasons. I had made up exactly the same (tried and successfull) modified D1 formula and rolled it to exactly the same size. I can´t think of any variable that changed except that probably ambient temperature; the first (good) batch I had rolled during spring. I don´t know if any undesired reaction took place just because of this change in ambient temp. I know that moist glitters don´t like heat so I always dry them indoors and never in the sun... What could have caused the formation of giant droplets which never send out spritzels in the end of the flight? Has anyone ever experienced something similar? It´s like using loads of delay agent...while they contain the exact 7% bicarbonate used earlier... Please advise! Stars were thoroughly dry by the way...
Twotails Posted July 10, 2010 Posted July 10, 2010 It may be that a "crust" formed on the outside of the star in flight, eather by the rection of your prime, or somthing maby having to do with moister in the air, while unlikely it may be somthing as simple as your chemicals are to corse, or to fine(unlikely probably) other than that I'm not sure what could have happened, it may be that your seeing a "droplet" effect similer to a seko-hanabi sparkler.
Cookieman Posted July 10, 2010 Posted July 10, 2010 I know of 2 things that would kill a glitter effect. Overwetting your comp. and a high mesh Al. content. Did you add any boric acid? I remember reading comments on Pyrotecknic.org that these stars work better pressed than rolled and that too much water makes them look more like a white star with few sparks. -325m spherical works best with D1.
al93535 Posted July 11, 2010 Posted July 11, 2010 Did you use different chemicals? Did you mix and screen them the same way? My guess is that the star didn't burn fast enough, therefore didn't eject small enough spritzels. They were simply too big to glitter, cooled and fell back to earth. Perhaps an error in weighing? If not, I'd say it wasn't mixed well enough.
AdmiralDonSnider Posted July 11, 2010 Author Posted July 11, 2010 (edited) I think I´ve already found the solution of my "fallout" issue. A post on rec.pyro reminded me of a detail I had forgotten. Last week, when the stars were set to dry, we had some muggy weather with high humidity for a couple of days, enough humidity to feel it oneself and to perspirate on every occasion. This ambient conditions didn´t allow the stars to dry properly. This doesn´t mean they´re still dry by now, but it took them days to dry out completely. Here is Lloyd Sponenburghs comment:"If they stay wet too long, they will become drossy, slow, and rather "inactive" in terms of spritzel output. The symptoms you describe - of dross falling without spritzels being ejected - is a common failure. Glitters can take quite a bit more moisture than the recommended maximum of 8% so often recommended in how-to books. However, any drying regimen that causes the stars to stay wet over about 48 hours will result in a deteriorated effect. The longer they stay wet, the worse the effect. The aluminum slowly reacts with the nitrate, so long as moisture is present." While aware about the detrimental impacts of wet reactions I personally did not know that the result could be the strange drossy behavior I had experienced. It seems that most of us are wrong subscribing to the theory that moisture (overwetting) harms the glitter. Instead it´s the long drying time (long wet phase) of the stars that presents the problem. Edited July 11, 2010 by AdmiralDonSnider
Mumbles Posted July 11, 2010 Posted July 11, 2010 I cut all of my stars. I've taken to drying the stars with a fan over night or 24 hours and then putting them in my new drying box. They tend to swell if I put them in right away. There is a lot of water lost right away when cut. My cut stars usually have 20% or a little bit more water in them. I'd bet it's down to 10-12% within a day or so. Pumped stars I can put in right away.
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