AzoMittle Posted August 14, 2016 Posted August 14, 2016 Can MgAl be swapped for Mg 1:1? I'm mixing up a batch of parlon colors (cut and bound with the parlon). Realized I'm short on MgAl and don't want to have to buy/wait for more just for this when I have plenty of Mg sitting around that I wanted to get rid of anyway.
Seymour Posted August 17, 2016 Posted August 17, 2016 Yes, but not always. Mg will corrode fast in mixes that MgAl lasts a lonh time in. For this application I'd say yes, but don't expect the stars to last yearsin perfect condition. 1
taiwanluthiers Posted August 17, 2016 Posted August 17, 2016 It will work, in fact the color will be more brilliant when you do this (if using green or red). However you should not water bound them, and add a little bit of dichromate to protect things.
AzoMittle Posted August 17, 2016 Author Posted August 17, 2016 Yes, but not always. Mg will corrode fast in mixes that MgAl lasts a lonh time in. For this application I'd say yes, but don't expect the stars to last yearsin perfect condition. Will it still corrode if I dichromate it? Does uncoated magnesium corrode on its own when not in composition (or in other words, what causes this corrosion?)? I've heard that mag doesn't form a protective oxidation layer the same way that aluminum (or magnalium) does. Would it be a good idea to go ahead and dichromate all of my mag now anyways for storage purposes, even if I don't plan to use it right away? I have more magnesium sitting around than I realized, time to use it up. I have some white, silver, and MTV formulas I plan to use some of it for. I guess I could use it for colored salutes/inserts but that kind of sh*t always makes me nervous. Anyways I'm just rambling, any suggestions are appreciated, thanks guys.
OldMarine Posted August 17, 2016 Posted August 17, 2016 Upon trusted advice, I pre-treated my Mg before storing. I have a small baggie of coarse mesh that a fellow pyro sent me to play with that was left untreated and after six months it has a black dull look to it rather than its original silver lustre. Better safe than sorry!
Mumbles Posted August 17, 2016 Posted August 17, 2016 Parlon binding will probably help with the corrosion aspect, but dichromate treatment would be a nice insurance policy too. The parlon binding may help with one other issue. Since you said you're working with colored compositions, it should be noted that barium and I believe strontium nitrates can strip the protective dichromated layer off by forming insoluble chromates. This can be a big issue when used in conjunction with other highly corrosive items, like AP. 1
AzoMittle Posted August 17, 2016 Author Posted August 17, 2016 Parlon binding will probably help with the corrosion aspect, but dichromate treatment would be a nice insurance policy too. The parlon binding may help with one other issue. Since you said you're working with colored compositions, it should be noted that barium and I believe strontium nitrates can strip the protective dichromated layer off by forming insoluble chromates. This can be a big issue when used in conjunction with other highly corrosive items, like AP. Veeeery good to know. Is there a better way to treat it when working with those nitrates then? I ended up using magnalium for that purple by the way. I also realized I ended up mixing AP with strontium nitrate, how likely is it that I ended up forming AN by accident? Hope I didn't waste my AP but they are noticeably different from the control batch, still burns fine but noticeably softer and stickier instead of rock hard.
Mumbles Posted August 17, 2016 Posted August 17, 2016 Potassium nitrate is the biggest issue with AP due to the very low solubility of potassium perchlorate greatly driving the equilibrium. Strontium and barium perchlorate are both reported to be extremely soluble relative to AP (~20g/100mL), so there is not as much worry. Sodium nitrate is also compatible with AP stars for what it's worth. You will still have to deal with the hygroscopic nature of sodium and strontium nitrates though. These things are all equilibria, so there is likely some degree of AN and strontium perchlorate formed. Between the two, strontium perchlorate is probably the bigger concern with regard to hygroscopic properties. Hopefully it's just a slower drying process. Dissolved parlon can be a pretty effective coating on it's own.http://www.amateurpyro.com/forums/topic/3835-coating-mg-with-parlon/
Seymour Posted August 17, 2016 Posted August 17, 2016 I just want to add that Mg will possibly not work at all if it is used instead of MgAl in crackle.
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