FlaMtnBkr Posted December 21, 2011 Posted December 21, 2011 I have a lot of 200 mesh mg and want to try substituting it for mg/al in some formulas. I don't want to have to use potassium dichromate if I can help it. I have read of using linseed oil, parlon in acetone, and gilsonite in naptha to coat metals. This sounds good but I can't imagine it being easy coating a fine metal with one of these and them not clumping into big blobs of metal. It seems like when it dries and the metal is broken apart and back into a powder there will be lots of uncoated areas that pulled away when breaking up the clumps. I am wanting to try Ned Gorski's system of colors that use parlon and acetone and are pushed through a screen to make uniform cut stars. Maybe using acetone and parlon and no water, using coated mg is not needed? Even if it's not easy, I would still like to figure out how to coat the metals for use in other formulas down the road. Any input would be great. How much to add to the metal and how to not have a big clump are the things I'm most interested in learning. Thanks!
Deafaid Posted December 21, 2011 Posted December 21, 2011 you can find info here: Mg and MgAl coatingMg/AL passivation
FlaMtnBkr Posted December 22, 2011 Author Posted December 22, 2011 you can find info here: Mg and MgAl coatingMg/AL passivation While I appreciate the links, the first one basically only says that one percent parlon and alcohol can be used to passivate mg and the second says mg/al doesn't need anything in most formulas. They don't tell how it is done or how to avoid problems. I can always experiment but I was hoping someone had already figured out a good way to do it and could share the process. I guess most people just use the carcinogenic potassium dichromate. Thanks
NightHawkInLight Posted December 22, 2011 Posted December 22, 2011 Here's a little bit more about parlon coating Mg, not very many people have tested it: http://www.amateurpyro.com/forums/topic/3835-coating-mg-with-parlon/page__p__53053__hl__%2Bcoating+%2Bparlon__fromsearch__1#entry53053
Mumbles Posted December 22, 2011 Posted December 22, 2011 If you want to use it in ammonium perchlorate strobes, you'll have to use dichromate. Linseed oil definitely doesn't work. I'm not sure about gilsonite. Parlon showed promise, but still needs testing. For the most part, yes, magnalium does not need any special treatment. It seems to be compatible with ammonium perchlorate, though may still benefit from some dichromate in the mix.
oldguy Posted December 22, 2011 Posted December 22, 2011 I tried to passivate some 30 mesh Mg with a gilsonite solution. Big PITA. Finally, got it to where it would pass a quick vinegar test , but it took 2 separate trips through a 1 gallon ultrasonic cleaner tank filled with a fairly thick gilsonite solution. After each trip the Mg was strained out, then spread out thin on a Teflon coated cookie sheet to dry. One soak & dry cycle didn’t do it, second did. But, anything smaller than 30 mesh would be a giant PITA, rather than a big PITA. Even then, I would not trust it for any length of time After going through all that messy gilsonite solution BS, I made some 50/50 Mg/Al & water quenched it. Which was air dried outside for a couple hot sunny summer days. Once dry, it would pass a vinegar test. My assumption being with that much Al in the Mg/Al alloy it forms a protective oxide layer over time anyway and water quenching helps it form a protective oxide layer immediately.
Peret Posted December 22, 2011 Posted December 22, 2011 I don't understand why you'd have reservations about "carcinogenic" potassium dichromate, which is harmful only with chronic exposure, yet be quite happy (in another thread) to work with the acute toxin Paris Green. Anyway, in terms of balancing risk, I think the negligible risk of poisoning yourself would be preferable to the considerable inconvenience of a fire from improperly passivated magnesium.
FlaMtnBkr Posted December 22, 2011 Author Posted December 22, 2011 I don't understand why you'd have reservations about "carcinogenic" potassium dichromate, which is harmful only with chronic exposure, yet be quite happy (in another thread) to work with the acute toxin Paris Green. Anyway, in terms of balancing risk, I think the negligible risk of poisoning yourself would be preferable to the considerable inconvenience of a fire from improperly passivated magnesium. Thanks for the replies. Peret: That's what I was hoping to find out with this thread is if there is a good alternative to the pot. dichromate. I have over a 100 lbs of 200 mesh Mg so would have much more frequent contact. I only have 2 lbs of paris green and will only make stars with it a few times so will have less contact with it and who knows when I will actually get around to using it. I'm sure I will be paranoid enough to wear a disposable 'bunny suit' and shower immediately after working with it. I would get tired of doing that if I had to do it every time I used Mg. I have a very rare blood disease from exposure to industrial toxins and will be lucky to live another 10 years (I'm 32) so I am extra paranoid when it comes to exposures to chemicals.
Peret Posted December 23, 2011 Posted December 23, 2011 I have over a 100 lbs of 200 mesh Mg Seriously?!? If I had 100 pounds of unpassivated 200 mesh magnesium laying around, I'd be out there shoveling dichromate into it right now before it has a chance to get damp.
oldguy Posted December 23, 2011 Posted December 23, 2011 If I had your #100 of Mg. I would set maybe 10 lbs aside & passivate with pot dich.The remainer I would make 50/50 Mg/Al out of & water quench it.Al scrap is cheap & can be found about anywhere.
FlaMtnBkr Posted December 23, 2011 Author Posted December 23, 2011 (edited) Seriously?!? If I had 100 pounds of unpassivated 200 mesh magnesium laying around, I'd be out there shoveling dichromate into it right now before it has a chance to get damp. Yep I have a 100 lb drum (it may be 50 kg) of 200 mesh magnesium that the manufacturer put it in probably 20 or 30 years ago and it is still sitting there. It has a secure lid that is tightened down good and I put a thick plastic bag over the top in case a hurricane rips the roof off the shop. It's also on wood blocks so air can move under it or an inch of water comes from somewhere. I bought it for cheap that someone bought a lot of as surplus material. He had about 90 drums of it sitting around. Unpassivated and unreacted. I opened it once to put about 5 lbs in a double bag. It was still all a nice uniform silver color. It hasn't burst into flames either. I also have about 25 lbs of scrap magnesium turnings that I would turn into mg/al before the drum of good magnesium. And I could probably get another 25 pounds or more when that is gone if I wanted it. It has probably been sitting around for 20 years as well going by the packaging. I have had it for at least 5. If I find out a good way to coat it I will be sure to share the results. Edited December 23, 2011 by FlaMtnBkr
Mumbles Posted December 25, 2011 Posted December 25, 2011 I have a 115lb drum of -200 mesh Mg too. If it's from the same place (a guy in Michigan or Chicago), it's actually from WWII era I've been told. Still very silver, fairly caked down, but in good overall quality.
pyrogeorge Posted December 25, 2011 Posted December 25, 2011 I coat my mgnal and mg with linseed oil.i haven't any problems and never clump like rock..i use 2-3% oil.
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