AldoSPyro Posted April 16, 2015 Posted April 16, 2015 Hey guys its been a long time but I'm back to pyro! Yesterday I started making some dark aluminum powder with shredded aluminum foil and a heaping tablespoon of charcoal dust. I used my ball mill which is a modified harbor freight rock tumbler with 3lb drums and lead-antimony balls. I remember someone saying that since hardened lead is softer than aluminum that it would be slightly consumed in the process and contaminate my powder, do you think that is an accurate statement because I dont really have any other media or grinding method. Do you think its safe to use my lead media? Thanks!
braddsn Posted April 16, 2015 Posted April 16, 2015 Just curious but what are you using this dark aluminum for? The lead contamination that will take place during this process will not affect the performance near as much as the fact that your aluminum will not be in 'flake' form. 1
LiamPyro Posted April 16, 2015 Posted April 16, 2015 All I know is watch out for the toxicity! That would be my personal main concern. Even if the hardened media is almost as hard as aluminum, which I doubt, a fair amount of it will still wear away and end up in your powder. Also, I doubt the powder will get much finer if the media is softer than it. One other thing, careful with the milling. I don't know much about the hazards of milling metal powders, but I know that magnesium/magnalium and possibly aluminum can become pyrophoric, which is definently not a fun thing. Hopefully you find a way to make your idea work!
pyrokid Posted April 16, 2015 Posted April 16, 2015 (edited) Pyrophoricity is a concern that must be attended to, but I'm pretty sure that the "make dark Al with normal Al and charcoal" is a bit of internet pyro lore, and not really grounded in reality. Real dark aluminum has its color due to surface oxidation and particle size. I guess I was half right. Read further: http://www.wichitabuggywhip.com/fireworks/aluminums.html Edited April 16, 2015 by pyrokid
AldoSPyro Posted April 16, 2015 Author Posted April 16, 2015 Just curious but what are you using this dark aluminum for? The lead contamination that will take place during this process will not affect the performance near as much as the fact that your aluminum will not be in 'flake' form.Just to see if I could make it, no real reason. One other thing, careful with the milling. I don't know much about the hazards of milling metal powders, but I know that magnesium/magnalium and possibly aluminum can become pyrophoric, which is definently not a fun thing. Hopefully you find a way to make your idea work!Also I dont really care about lead contamination more than the fact that my media might wear down, its pretty expensive, will it significantly wear my media? Also wouldn't the charcoal keep it from oxidising and prevent it from becoming pyrophoric?
MrB Posted April 16, 2015 Posted April 16, 2015 Just curious but what are you using this dark aluminum for? The lead contamination that will take place during this process will not affect the performance near as much as the fact that your aluminum will not be in 'flake' form.How do you figure? As far as i know, the only kind of powder we can make from (ball)milling metals is "flake". The main issue i see is the particle size. Stuff tends to clump together the way we mill it. Also, adding charcoal to aluminum isn't how they make "dark aluminum powder" but it just might prevent some of the clumping action. Not sure about how safe it is, but supposedly blade milling helps prevent some of the clumping as well, but i'm not sure if it's even able to reduce the stuff to a size where this becomes an issue. Speaking about the wear on your media. I'd really suggest getting stainless steel media for this, or ceramic. Your not only contaminating your aluminum with lead, but also the other way around. Lead isn't much to worry about as a contaminant, but alu might throw your colors off. What i'm saying is, you might have saved a few bucks not buying proper alu, but you lost more, now that you need to by new media anyway... Just my opinion, of course.B! 1
schroedinger Posted April 16, 2015 Posted April 16, 2015 1st. Yes for this attempt you need to use better suited media, brass or non spark steel are the best. 2nd. Since you are making flake Al and not atomized, it isn't needed to grind it down to <10 microns to make it performing right. 3rd. Like allready mentioned watch out that the Al can breath, open your mill multiple times during the run, at least every 12 hours. 4th. The charcoal added to the Al isn't a internet mith, but a little bit often a little bit missinterpreted. It is added as a surface inhibitor, so it is used to slow down the oxidation, for nothing else. It original comes from the old german dark patent, which is atomized in an inert atmosphere.Other ingredients that got used for the same purpose are e.g. waxes or graphit.Use it but do not rely on it pay attention to 3. 5th. A faster method can be to grind down your al foil by using a blender, a good blender will take about 500 g of Al and turn about 400g down <20 mycrons in about a hour. This is fine enough. The trick is to blend the Al together sith water. The water serves two purposes, it cools the al and it also serves as a oxidation agent, which is much less effective compared to air. If the blender becommes hot, let it cool before going on. If you get cakes of al formed after drying, run them for 1 hour in a ball mill and you got a free flowing powder again.
AldoSPyro Posted April 16, 2015 Author Posted April 16, 2015 How do you figure? As far as i know, the only kind of powder we can make from (ball)milling metals is "flake". The main issue i see is the particle size. Speaking about the wear on your media. I'd really suggest getting stainless steel media for this, or ceramic. Your not only contaminating your aluminum with lead, but also the other way around. Lead isn't much to worry about as a contaminant, but alu might throw your colors off. What i'm saying is, you might have saved a few bucks not buying proper alu, but you lost more, now that you need to by new media anyway... Just my opinion, of course.B!ive milled for about 6-8h already and Ive stopped milling (ill buy some steel media), do you think that my lead media is ok to still use? its only been reduced maybe by like a half mm to mm?
Arthur Posted April 16, 2015 Posted April 16, 2015 (edited) I did once read a PDF online that was someone's research project to make fine pyro aluminium from soft drinks cans. They were successful after a fashion BUT after the preparatory work the final mill time was measured in weeks 24/7. It's possible but actually expensive in electricity. AND it's hazardous. Their initial finding was that without exactly the right mill charge the powder hit quite a large minimum size then reagglomerated again. Read this carefully http://www.pyrobin.com/files/wet%20aluminum%20powder%20fabrication.pdf Edited April 16, 2015 by Arthur
otto Posted April 16, 2015 Posted April 16, 2015 I did this a long time ago. Sometime before I stumbled in here and got educated.... I ran shredded foil in a blender for a while (dry) and it turned into little spheres of crumpled AL. Didn't know to go wet or for an hour (really?). My brain reasoned my rock tumbler re-purposed as a ball mill might do the job. I used a pile of 1/2 SS bolts with two nuts threaded (locked) on. At least I knew enough to use something non-sparking. That mill would run 24/7 for days, I never kept track. I'd open it once and a while and sift some out. Used one of those coffee filter cones, it was the finest thing I could my hands on. Probably my saving grace to open periodically and remove the finest stuff. Anyway, it took a long time, was a pain to babysit and didn't return much for the effort. I'm buying my Al from here on in. I still have a tub of those little spheres from the blender and a whole box of clean foil. Seems like there should be a way to get them lit and do something constructive..... Best part? Moron survived the Darwin Award. I did this in my basement. Never again!
Sparx88 Posted April 17, 2015 Posted April 17, 2015 Blender and water. Makes perfect sense to me. There's a youtube video of aluminum milling machine a guy custom built that uses a large grinding wheel half submerged in a water tank with an ingot of aluminum under tension againts the grinding wheel. Very slick so the blender/water is a good idea. Though maybe not as flakey as flake is supposed to be but would work for most pyro just fine I imagine.
schroedinger Posted April 17, 2015 Posted April 17, 2015 Yes the trick is to use water if you blend mg or al. The first -500 mesh al is allreadyroduced after 1 minute, but the bulk is much bigger. After about 10 minutes milling time the main fraction is <80 mesh with about 30% <120 mesh. If you want firefly or flitter al then you are allready done here, for finer al keep blending.
Arthur Posted April 17, 2015 Posted April 17, 2015 Remember that fine metals are pyrophoric, they will/may burst into flames. This really is a case for a good method, AND good PPE.
carbonhalo Posted April 17, 2015 Posted April 17, 2015 Have you thought of pouring molten lead into aluminium tube and using sections of that for media? should solve the contamination problem
schroedinger Posted April 18, 2015 Posted April 18, 2015 Remember that fine metals are pyrophoric, they will/may burst into flames. This really is a case for a good method, AND good PPE.Arthur this is as wrong as you can be. It is only pyrophoric in a very special situation and that is if the metall got reduced to a finer size without any oxidation ability for the new, clean surfaces.Also it is possible if you precipate a finely divided metal from an organic solution.Once the surface is oxidized they are stable.
Arthur Posted April 18, 2015 Posted April 18, 2015 Well I have a friend who was BADLY burned as a result of milling a metal (magnalium I think). If you need to mill metals than you need to think about your method and PPE.
MrB Posted April 18, 2015 Posted April 18, 2015 Well I have a friend who was BADLY burned as a result of milling a metal (magnalium I think). If you need to mill metals than you need to think about your method and PPE.Goes in line with what he's saying. It's only reactive like that, straight out of the mill, and only since it consumed all the oxygen inside the milling jar, and hence comes out without the protective oxide layer. Solutions for circumventing this problem ranges from additives that coat it, to opening and letting in oxygen at regular intervals.In theory you should be able to mill it in one long straight go, and then just open a tiny hole for the air. Over time it "should" let the oxygen from the surrounding air do it's thing, and be possible to open the jar safely, but the time-frame depends on the size / numbers of holes, how stable your temperature is, and so on.Could be hours, could be months. I have no idea. Currently i mill small amounts in a blade coffee-mill. It seams safer.B!
FlaMtnBkr Posted April 18, 2015 Posted April 18, 2015 I think Arthur just left a word out of his sentence. It's pretty obvious he meant 'finely milled metals' and not just fine metals. We probably all use fine metals and they don't burst into flames. But recently milled metals that had any oxidation layer removed can burst into flames while the metals exothermically oxidize. The point is that if you are milling metal powder you need to take the proper safety precautions and wear protective gear that will protect you in case of a intense metal fire. You need to also think about UV radiation that can burn you across the room and not just flames.
Arthur Posted April 18, 2015 Posted April 18, 2015 Thanks FlaMtnBkr it reads better as you put it for me. If you are milling metals to fine powder then you do need good safety practises.
LiamPyro Posted April 20, 2015 Posted April 20, 2015 Just to see if I could make it, no real reason. Also I dont really care about lead contamination more than the fact that my media might wear down, its pretty expensive, will it significantly wear my media? Also wouldn't the charcoal keep it from oxidising and prevent it from becoming pyrophoric?Yes, I think it would probably wear down your media quite a bit, so I wouldn't reccomend it. I've heard that charcoal can help prevent pyrophoricity, but I don't know enough to be sure.
Mumbles Posted April 21, 2015 Posted April 21, 2015 ... 4th. The charcoal added to the Al isn't a internet mith, but a little bit often a little bit missinterpreted. It is added as a surface inhibitor, so it is used to slow down the oxidation, for nothing else. It original comes from the old german dark patent, which is atomized in an inert atmosphere.Other ingredients that got used for the same purpose are e.g. waxes or graphit.Use it but do not rely on it pay attention to 3..... I'm interested in taking a look at this patent. Care to share a number with us?
gregh Posted April 22, 2015 Posted April 22, 2015 I thought the old german dark was flake and not atomized...
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