dagabu Posted June 11, 2014 Share Posted June 11, 2014 I guess I dont understand the concerns with Mg/Al, I have Mg/Al that was several years old when I got it and I have had it for half a decade and it shows no less brightness then when I first got it. Its been over a year since I made anything with it but it worked fine back then... Link to comment Share on other sites More sharing options...
LiamPyro Posted June 12, 2014 Author Share Posted June 12, 2014 I guess I dont understand the concerns with Mg/Al, I have Mg/Al that was several years old when I got it and I have had it for half a decade and it shows no less brightness then when I first got it. Its been over a year since I made anything with it but it worked fine back then... Interesting! I have heard very controversial things about magnalium oxidation. Some say it gradually oxidizes and eventually becomes unusable. Others say it develops an oxide layer within seconds in air, like aluminum, and does'nt further oxidize. Yet others say MgAl does'nt oxidize at all. Btw what mesh size is your MgAl? Do you know if it is coated? Link to comment Share on other sites More sharing options...
LiamPyro Posted June 12, 2014 Author Share Posted June 12, 2014 I'm probably wrong, but I think one reason why MgAl is sometimes coated is to reduce it's ignitabilty and raise the ignition temperature of the composition it is in, therefore making it safer to handle. Link to comment Share on other sites More sharing options...
psyco_1322 Posted June 12, 2014 Share Posted June 12, 2014 I'm probably wrong, but I think one reason why MgAl is sometimes coated is to reduce it's ignitabilty and raise the ignition temperature of the composition it is in, therefore making it safer to handle. Yeah that's totally wrong. When you hear about coated magnalium, it's usually in a comp with ammonium perchlorate (AP). It refers to is a potassium dichromate coating, which you have to put on yourself. If you buy magnalium from somone, is it not coated. AP is really the only thing that attacks magnalium, thus you don't need a coating on it for any other comps, or storage. This is totally different from what coated Al refers to. Al is usually coated with stearic acid when it's milled. This prevents the Al from oxidizing, it's stay shiny, and now it's what we call bright Al. Magnalium is never made with stearic acid coatings, so you won't see any form of "bright magnalium". Link to comment Share on other sites More sharing options...
dagabu Posted June 12, 2014 Share Posted June 12, 2014 But my Mg/Al is bright... Link to comment Share on other sites More sharing options...
dagabu Posted June 12, 2014 Share Posted June 12, 2014 I'm probably wrong, but I think one reason why MgAl is sometimes coated is to reduce it's ignitabilty and raise the ignition temperature of the composition it is in, therefore making it safer to handle. I have only coated Mg/Al with Potassium Dichromate and only when making AP falling leaves. I didn't do it to alter the burn rate but to protect the metals from oxidization in the comp. Link to comment Share on other sites More sharing options...
LiamPyro Posted June 12, 2014 Author Share Posted June 12, 2014 Thanks for clearing that up! Speaking of unwanted reactions between metal fuels and oxidizers, what's the deal with aluminum and nitrate? I've heard mixes with those two chemicals together degrade over time or if exposed to moisture. I've even heard they can even spontaneously ignite. I think the reaction can be slowed down with boric acid, but is that necessary? I'm curious because I want to use KNO3/Dark Al/Sulfur slow flash to break 1.5 inch ball shells, in addition to BP rice hulls of course. Would the nitrate in this mix still attack the Al, even though it is dark? Link to comment Share on other sites More sharing options...
Shadowcat1969 Posted June 12, 2014 Share Posted June 12, 2014 Yes, Dag, my MgAl is also nice and bright, several different mesh sizes, and some of it I know is over 4 years old, stored in ziplock bags in a glad "tupperware" type container. So nowhere near airtight, lol. It still works quite nicely too. I simply was replying to the question about what to coat it with, if you wanted to coat it, which I never have (I've not done any AP comps yet). Link to comment Share on other sites More sharing options...
FlaMtnBkr Posted June 12, 2014 Share Posted June 12, 2014 The nitrate and aluminum is only a problem when wet with water and is not an issue when dry. It is also usually only a problem with high amounts of aluminum and/Or it stays wet for a really long time. It seems like someone very knowledgeable (Mike S or Lloyd S.) also said they have only had a problem with glitters with sodium oxalate and is the only time they add boric acid. I have yet to notice a problem with the two. Link to comment Share on other sites More sharing options...
psyco_1322 Posted June 13, 2014 Share Posted June 13, 2014 The nitrate/Al reaction is mostly an issue in basic conditions. The boric acid takes care of this. Most of the time there is no issue with the reaction occurring though. I think some of the magnalium that Karl was selling a few years ago is not the normal 50:50 by weight alloy. It behaves and looks like there is more Al in the alloy. I've talked with some people and heard that sometimes magnalium is made 50:50 by mol, and thus results in a higher Al content. Mine stills seems to work in most formulas, but you can tell it's off a bit. Link to comment Share on other sites More sharing options...
MrB Posted June 13, 2014 Share Posted June 13, 2014 As i said, i have as of yet to research if, and how to coat magnalium. The reason for any coating would be, of course, storability. Reading turns up concerns, and since i'm milling it anyway, adding the coating component wouldn't really be an issue. But just from reading the last few responses, it seams it might not be an issue. I'll look in to it some day...B! Link to comment Share on other sites More sharing options...
dagabu Posted June 13, 2014 Share Posted June 13, 2014 As i said, i have as of yet to research if, and how to coat magnalium. The reason for any coating would be, of course, storability. Reading turns up concerns, and since i'm milling it anyway, adding the coating component wouldn't really be an issue. But just from reading the last few responses, it seams it might not be an issue. I'll look in to it some day...B! Unless you are in a humid/salty location, you don't have the corrosion triangle to be concerned with. Mg cannot just corrode by itself and with Al intermixed, there should be no reason to think it has to be coated, just keep oxygen/water away and there should be no need for concern. Link to comment Share on other sites More sharing options...
LiamPyro Posted June 13, 2014 Author Share Posted June 13, 2014 Would storing MgAl in a plastic screw-lid container be good? It would be airtight but there would still be some oxygen with it. I don't want to spend a lot of money on some MgAl just to have it go bad! Link to comment Share on other sites More sharing options...
dagabu Posted June 13, 2014 Share Posted June 13, 2014 Displace the air with something else, Argon gas, Helium, a balloon or a zip lock bag full of air and you decrease your exposure immensely or just use a container that is to the brim full of your Mg/Al. I have a pyro buddy that was paranoid about some Mg dust he had for lampare shells so he took up the extra space with some rocks... The container burst from the corrosion that was taking place since the rocks contained so much moisture. Something like ping pong balls might be good too. Link to comment Share on other sites More sharing options...
LiamPyro Posted June 13, 2014 Author Share Posted June 13, 2014 Thanks for the ideas! I'll probably store it in a ziplock bag with the air squeezed out, and maybe put that in a container just to make it easier to store on a shelf.Also, I bet tossing one of those silica gel packets in the bag or container would help a lot since they would absorb any traces of moisture. I read that they are actually used to prevents rust, corrosion, and oxidation! Link to comment Share on other sites More sharing options...
dagabu Posted June 13, 2014 Share Posted June 13, 2014 Only if it's a new silica gel pack, if used or sat out for any time at all, its junk. Link to comment Share on other sites More sharing options...
LiamPyro Posted June 14, 2014 Author Share Posted June 14, 2014 I heard they can be dried in an oven and then reused. Makes sense, 'cause the reason why the packets absorb moisture is becuase they are extremely hygroscopic (I think). Link to comment Share on other sites More sharing options...
pyrojig Posted June 14, 2014 Share Posted June 14, 2014 NO need as Dag said. I have found that proper storage is the only thing needed. No descants are needed. Just take the advise of these fellows and use a couple zip locks rolled up tight and store in a well sealed container . I have many #s that sore for years and years w/o degrading . Now if the material is super fine like -400 mesh or smaller , then it may be more prone to degrade , but again with the "proper " storage your material will be fine. Link to comment Share on other sites More sharing options...
dagabu Posted June 16, 2014 Share Posted June 16, 2014 I heard they can be dried in an oven and then reused. Makes sense, 'cause the reason why the packets absorb moisture is becuase they are extremely hygroscopic (I think). "The gel can be regenerated by heating it to 120 °C (250 °F) for two hours." The big caveat to that is the use of natural gas introduces a lot of water into the air, the typical gas stove has 16,000-17,000 BTU and releases about a quart of water into the oven. Two hours can release a half gallon of water into the chamber and your desiccant gets really hot but not a whole lot lighter. Use an electric oven to dry the packages but be aware, a lot of them are in Tyvek envelopes, it melts at 275 °F but deforms at the target 250 °F you need for the desiccant. 1 Link to comment Share on other sites More sharing options...
MrB Posted June 16, 2014 Share Posted June 16, 2014 Unbag em, heat em in a electric oven, and reuse em. Works great. Dagabu is spot on.B! Link to comment Share on other sites More sharing options...
countryboy7978 Posted June 19, 2014 Share Posted June 19, 2014 (edited) OMG this thread is giving me a headache. All this talk of oxidation and milling MgAl.......What?? I have some very fine MgAl that I bought from a guy in NY many years ago on ebay. It looks like IBA. It is not available anymore but I'm just using it as an example. I stored it in the large ziplock bag in came in for all these years. It has not shown me any signs of degrading and I've opened and closed the bag dozens of times since I've owned it. Whoever said the finer stuff is weaker must be using atomized rather than flake. There is no way that it is weaker than the -325 stuff BTW. A 50:50 or 55:45 mix will rock your world and probably give you a suntan from all the UV it releases. In larger quantities it sounds a bit louder than regular 70:30 but for the added expense it's not really worth it. The formulas use a greater quantity of your more expensive MgAl than typical Al formulas. In smaller quantites the stuff self-confines in a rather dramatic way. Approximately a 1-2 gram pile ignited in the open with a fuse will produce a loud report with no confinement. Do not test it with a match or a torch. With that being said just stick with the regular mix of 70:30. Using IBA and good perc will produce an FP leagues better than what you will find in most any Chinese report items. If it's not impressing you then you are doing it wrong plain and simple. Edited June 19, 2014 by countryboy7978 1 Link to comment Share on other sites More sharing options...
LiamPyro Posted June 21, 2014 Author Share Posted June 21, 2014 Thanks for all the helpfull replies! A quick question, wouldn't superfine particles inevitabily be present in any mesh of MgAl powder, therefore causing the rest of the mix to degrade more easily or have other problems? Link to comment Share on other sites More sharing options...
pyrokid Posted June 21, 2014 Share Posted June 21, 2014 I don't think the presence of MgAl dust would accelerate the degradation of the particles that fall within the advertised mesh range. The trend in all the replies in this thread is that oxidation/spoilage isn't something to be overly concerned about. It isn't difficult to see that these things may occur over time, but you have to approach it from a practical perspective as well. Do you care if the material oxidizes at some rate if it doesn't affect the performance of your comps? Link to comment Share on other sites More sharing options...
psyco_1322 Posted June 21, 2014 Share Posted June 21, 2014 (edited) Thanks for all the helpfull replies! A quick question, wouldn't superfine particles inevitabily be present in any mesh of MgAl powder, therefore causing the rest of the mix to degrade more easily or have other problems? The amount of fine particles is going to depend on the supplier, and how the material was sized. If they don't screen out the fines, their is likely to be some in there. That doesn't mean it's going to affect the rest of the material, it usually migrates to the bottom of the bag anyways. Putting a tablespoon of powdered sugar in a bag of normal granulated sugar isn't going to make the rest of it turn into powdered sugar. Magnalium doesn't really "oxidize" as you keep thinking, it's not going to go bad just setting in a bag. These are only helpful replies if you take something from them and learn. Stick with some dark Al, 70:30 flash, and build some better rockets to lift headers that are bigger than black cats. Edited June 21, 2014 by psyco_1322 Link to comment Share on other sites More sharing options...
ddewees Posted June 21, 2014 Share Posted June 21, 2014 OMG this thread is giving me a headache. All this talk of oxidation and milling MgAl.......What?? I have some very fine MgAl that I bought from a guy in NY many years ago on ebay. It looks like IBA. It is not available anymore but I'm just using it as an example. I stored it in the large ziplock bag in came in for all these years. It has not shown me any signs of degrading and I've opened and closed the bag dozens of times since I've owned it. Whoever said the finer stuff is weaker must be using atomized rather than flake. There is no way that it is weaker than the -325 stuff BTW. A 50:50 or 55:45 mix will rock your world and probably give you a suntan from all the UV it releases. In larger quantities it sounds a bit louder than regular 70:30 but for the added expense it's not really worth it. The formulas use a greater quantity of your more expensive MgAl than typical Al formulas. In smaller quantites the stuff self-confines in a rather dramatic way. Approximately a 1-2 gram pile ignited in the open with a fuse will produce a loud report with no confinement. Do not test it with a match or a torch. With that being said just stick with the regular mix of 70:30. Using IBA and good perc will produce an FP leagues better than what you will find in most any Chinese report items. If it's not impressing you then you are doing it wrong plain and simple.What surprise... a goofy post by CB about flash power or salutes. Link to comment Share on other sites More sharing options...
Recommended Posts