metalhead Posted June 8, 2010 Posted June 8, 2010 Hey all, I think my magnalium may have been oxidized a bit. I was adding another 1/2 lb in and noticed the newer magnalium was noticeably darker in color. Is the lighter color a sign of oxidation? is it still usable?
AdmiralDonSnider Posted June 8, 2010 Posted June 8, 2010 I noticed that MgAl coming from different sources can look differently. Other than that finer metal will appear darker, while coarse grades will be silver in color. I don´t think that it oxidized - what should have caused that? Normal air contact will not cause any change, at least I do think so.
ExplosiveCoek Posted June 8, 2010 Posted June 8, 2010 I'm with AdmiralDonSnider, I once ballmilled it to get my chunks to a smaller mesh size. But I let it in my mill for something like 6 hours, so it came out a lot darker (smaller?) then the batches I had been milling for only 2-3 hours . Of course it could haven been oxidized, but I doubt it since my buell red turned out quite nice.. and fast .
metalhead Posted June 8, 2010 Author Posted June 8, 2010 hmm, that's weird because both tubs of mine were from skylighter and they were both 200 mesh.
Peret Posted June 9, 2010 Posted June 9, 2010 (edited) I too noticed that Skylighter's MgAl is strangely dark recently compared to MgAl from other suppliers, though they feel of equal fineness by the unscientific method of rubbing a pinch between my fingers, and they seem to perform the same. I wondered if maybe Skylighter's is passivated, or coated with something like stearine from the mill. Edited June 9, 2010 by Peret
Mumbles Posted June 9, 2010 Posted June 9, 2010 It's more likely that Skylighter just has old or surplus MgAl. Fresh MgAl drums are very silver in color. As you use them, and get toward the bottom, it takes on a darker color. My old MgAl is noticably darker than fresh MgAl.
Peret Posted June 9, 2010 Posted June 9, 2010 It's more likely that Skylighter just has old or surplus MgAl. Fresh MgAl drums are very silver in color. As you use them, and get toward the bottom, it takes on a darker color. My old MgAl is noticably darker than fresh MgAl.So maybe it does oxidize, or react with something in the air, over time. I have that problem with a silver chain I wear. The morning after a shoot I find it's turned almost black with silver sulfide. My wife is sick of cleaning it for me and reminds me to take it off now.
PyroMan LTU Posted June 9, 2010 Posted June 9, 2010 I have diffrent magnalium and magnesium powders. And new mgal and mg is bright metllic silver in color, though the old ones are so dark.. magnalium just grey and magnesium black grey.. I doesn't change it's properties too much in colored stars for example. Only noticible diffrence is that dark mgal doesnt work in dragon eggs at all, it just burns with sharp sound. I believe this might be a problem with that reacted outside layer of the particles, since DE require very specific mgal, I believe.. Which allows the smolder reaction with Mg which is inside mgal, not oxides. Like nitrate sulfur strobes. PyroMan
Bonny Posted June 9, 2010 Posted June 9, 2010 Only noticible diffrence is that dark mgal doesnt work in dragon eggs at all, it just burns with sharp sound. I believe this might be a problem with that reacted outside layer of the particles, since DE require very specific mgal, I believe. PyroMan I disagree here. I have MgAl that is a few years old and very dark and it works great in dragon eggs... no different than the lighter "newer" stuff.
PyroMan LTU Posted June 9, 2010 Posted June 9, 2010 That's odd, in my opinion. what chemicals did you use? I used lead tetraoxide/mgal/CuO. My grey mgal is kind of coarse and low quality, but when I got mine 200mesh bright, it worked well.
Bonny Posted June 10, 2010 Posted June 10, 2010 That's odd, in my opinion. what chemicals did you use? I used lead tetraoxide/mgal/CuO. My grey mgal is kind of coarse and low quality, but when I got mine 200mesh bright, it worked well. I make mine with Bi2O3, MgAl, CuO and Al, bound with ping pong ball NC. i've made then with 60, 100 and 200 mesh. The 60 mesh were the loudest, but the smoulder phase seemed to take forever...5 seconds or more. I've settled on using 100 mesh. I did find that cut or pumped is better/louder than screen granulated. When I make more (no time soon) as I made quite a large batch last time, I'm going to make a multi hole pump from a pc of copper pipe and an end cap. I used a garlic press and it worked very well aside from the comp oozing out the gaps. I think it was Frozentech's idea.
PyroMan LTU Posted June 11, 2010 Posted June 11, 2010 That's a good idea, I use 200mesh and smolder time is around 1-1.5s
gordohigh Posted June 24, 2010 Posted June 24, 2010 I'm going to need to make some more dragons eggs soon and I still remember what a pain it was to work with when granulating thru a 12 mesh screen. With the garlic press method do you use anything in the top like waxed paper to try to keep it clean as possible and does it require cleaning with acetone between each press? My last batch, (and first time I made them), worked well but I feel I wasted some both on my gloves and in the baggie I mixed them in, any tips would be welcome. Also, If I remember right, the acetone ate thru my nitrile glove on the finger tips, is there a better glove for this than nitrile?
FrankRizzo Posted June 24, 2010 Posted June 24, 2010 (edited) I'm going to need to make some more dragons eggs soon and I still remember what a pain it was to work with when granulating thru a 12 mesh screen. With the garlic press method do you use anything in the top like waxed paper to try to keep it clean as possible and does it require cleaning with acetone between each press? My last batch, (and first time I made them), worked well but I feel I wasted some both on my gloves and in the baggie I mixed them in, any tips would be welcome. Also, If I remember right, the acetone ate thru my nitrile glove on the finger tips, is there a better glove for this than nitrile? Gordo - You need a thicker nitrile glove. The disposable ones become weakened by the acetone, and wear through at the contact points. Check out the kitchenwares or painting section of your local retailer and look for the thick nitrile gloves you might use to protect your hands while washing the floor or using paint stripper. http://www.webstaurantstore.com/nitrile-glove-flock-lined-15-mil-large-1-pair/nitrile-glove-flock-lined-15-mil-large-1-pair.jpg Edited June 24, 2010 by FrankRizzo
oldguy Posted July 9, 2011 Posted July 9, 2011 Hey all, I think my magnalium may have been oxidized a bit. I was adding another 1/2 lb in and noticed the newer magnalium was noticeably darker in color. Is the lighter color a sign of oxidation? is it still usable? DIY Water quenched Mg/Al is darker.
Bonny Posted July 9, 2011 Posted July 9, 2011 With the garlic press method do you use anything in the top like waxed paper to try to keep it clean as possible and does it require cleaning with acetone between each press? Gordo, I didn't see this post until now. The garlic press did get mucked up, but worked well. It needed a scraping every second or third loading IIRC, as well as comp oozing out between the plunger and the cup parts. I was using a cheap dollar store garlic press though. When I make some more I'm going to try something a bit different.
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