vladou Posted October 7, 2009 Posted October 7, 2009 (edited) Hello, I was wondering if I just can pass my chemicals through a 100mesh screen to make stars compositions. I don't want to ball mill all my chemicals but i don't know if they will be enough fine.. Also, I could just mill oxyders like KClO4, Ba(NO3)2, Sr(NO3)2.. ? Thanks for your help =) Edited October 7, 2009 by vladou
AdmiralDonSnider Posted October 7, 2009 Posted October 7, 2009 (edited) It is indeed a common practice to separately pass the chemicals through e.g. a 100 mesh to make the mesh size uniform. If the same sieve is used it should be cleaned after each use to avoid contamination or hazardous chemical combinations. In practice many pyros tend to avoid prescreening (as outlined above) or grinding and will try to use the chemicals as is. It is plain that this only works well if the chems are already fine enough for use. This depends on the source, but many chemicals will generally come fine enough (even if they clump) e.g. KClO4, KClO3, Carbonates, Oxides, Sulhur etc. while others show a well-known particle size e.g. Parlon, PVC, Metals. As far as I´m involved I regularly have to reduce nitrates, red gum etc. in a well-cleaned coffee grinder. As I said, this will depend on your supply. Prescreening is and remains a good idea, but is tedious. Just in case of confusion: fine sieves such as a 100mesh are good for prescreening, but for mixing coarser mesh-sizes are employed, e.g. 40 mesh. Edited October 7, 2009 by AdmiralDonSnider
Swede Posted October 7, 2009 Posted October 7, 2009 In addition, YES you can mill an oxidizer so long as it has NO fuel. Keep everything squeaky clean to avoid contamination. Chlorates and some ammonium compounds (esp. the perchlorate) can have serious problems with contamination. Most guys have dedicated jars and media to mill chlorate, as well as a separate screen or three obviously labeled CHLORATE ONLY. Certain chemicals can compact and clump horribly when ball milled. Benzoate comes to mind. Red Gum as far as I am concerned cannot be ball milled - it formed a concrete gum layer in my jar. Maybe if it was dry... but I'll never attempt it again. Do not ball mill metals until you have infinitely more experience. Even then, it's probably a bad idea.
AdmiralDonSnider Posted October 7, 2009 Posted October 7, 2009 Swede is right, but milling oxidizers for use in common star comps is just unnecessary. You can mill some lumpy KNO3 for half an hour, sure, but who really uses ballmilled perc in stars?
Seymour Posted October 7, 2009 Posted October 7, 2009 One thing to note about Ba and Sr nitrates, is that besides burn rate, particle size does affect colour saturation. If they look like sugar, mill them up till they are fine, even if only in a coffee grinder.
TrueBluePyro Posted October 7, 2009 Posted October 7, 2009 Swede is right, but milling oxidizers for use in common star comps is just unnecessary. You can mill some lumpy KNO3 for half an hour, sure, but who really uses ballmilled perc in stars? Sometimes they do have to be ground. Like my Barium nitrate is a bit finer then sand. I have to ball mill it if I want the white strobe bleser #26 to work. But yeah, other then my barium nitrate, I dont ball mill anything else for stars, unless it is charcoal based then I might ball mill it.
vladou Posted October 8, 2009 Author Posted October 8, 2009 (edited) Ok, thanks everybody I bought my chemicals from Czort. Ba(NO3)2, Sr(NO3)2, BaCO3, PVC, KClO4 and CuO are definitely not enough fine. I didn't know if it was best to mill all my chemicals and mix them directly or mill oxyders and other stuffs separately every time and then mix when making stars compositions.. But if chemicals don't have to be ball milled I think I will just pass them in my coffee grinder and then through my 100 mesh screen. This week end I will try to roll some Shimizu red organic stars in my star roller and see if it's ok. Edited October 8, 2009 by vladou
Mumbles Posted October 8, 2009 Posted October 8, 2009 There is a big difference between clumpy and coarse. You might want to try passing some of the chemicals through a screen to see how well that works for you. The PVC you might be stuck with. All the stuff I have is slightly granular, and I get a little bit retained even on my 60 mesh screen. I don't frequently use PVC, but even it's slightly coarse state I've never had problems. That stuff is so static-y, I can't screen it alone. Most of my chemicals are acceptably fine with minor coarse particle presence. I just toss the coarse stuff out as I'm screening. The percentage is so small I don't worry about changing the effect.
AdmiralDonSnider Posted October 8, 2009 Posted October 8, 2009 I bought my chemicals from Czort. Ba(NO3)2, Sr(NO3)2, BaCO3, PVC, KClO4 and CuO are definitely not enough fine. I know his materials and both nitrates have to be coffee-milled for a few seconds...works very well. I´m quite sure the other chems are fine enough, carbonates and oxides tend to come extremely fine, at least where I´ve bought them so far. PVC works well even if not as fine as talcum, try it! And KClO4 is just clumpy, works flawlessly when coffee-milled, screened or even crushed by hand.
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