Aluminum (Al) and magnesium (Mg) are useful metal for pyros because of their burning properties. They can be used for flash powder and, in larger flakes, for spark effects. You can get Al and Mg from various suppliers, but if you can't, there are still ways to make useful metal powders.
The best way to make fine Al powder from what I have read (I havenÔø‡t tried myself because I have access to high quality metal powders) is to use a combination blending and milling process. Get aluminum foil and tear it into squares about an inch square. Put these in a motorized food blender (not one you use for eating! You could find a cheap one at a used appliance store or something) with enough water to cover it. The Al squares should be added slowly rather than all at once to avoid overheating it. Only run the blender for a short time before letting it cool a bit and repeating. Once the Al isnÔø‡t getting any finer, pour all the liquid into a beaker or other container and let it sit. This will allow the Al to settle to the bottom so you can pour off most of the water. This is then dried. It can be used for different things depending on how fine it is. If you want to make flash powder with your Al, you should put it in a ball mill and basically mill it as long as you can stand to wait (hours and hours!). You canÔø‡t just turn it on and leave it however, because this can cause the metal to become pyrophoric, meaning it will catch on fire when you open it and it is exposed to fresh oxygen. To avoid this, open the milling jar every few hours to let it air out for a couple minutes. The longer you mill, the smaller your powder will be (to a point). I couldnÔø‡t say exactly what mesh size you will get because it depends on so many different factors. Test it out yourself to find how to make it work!
Go to a hiking store and many have Mg fire starters. I got mine at REI for $5. They are solid blocks of Mg a bit longer, and about the same thickness, as a matchbox. On one side they have a flint strip. What you are supposed to do with it is scrape of some Mg and light it with the flint. This is used to light a fire when a lighter or matches are not available, or when things are wet. For aluminum you could use aluminum cans or something, many things are made from aluminum that could be used. Both metals can apparently be purchased from scrap yards and probably metalworking shops, but I have not tried this myself. I got an email from somebody who said they purchased a 5lb. chunk of Mg at a scrap yard for four dollars (USD)! Much cheaper than Mg firestarters... Read the article below...
To get a decent amount of Mg, use a metal file and just scrape away. It takes a while... Wear breathing protection because it gets into the air. Also be careful not to scrape the side with the flint and ignite all you powder! Then you will feel stupid as well as having burnt up your Mg, burning your work surface, and possibly yourself. The same can be done with Al and a file. A faster way to do this would be to use some kind of motorized tool like a dremel tool or a grinder to powder the metal.
I've heard that aluminum powder of various mesh sizes can be found inside Etch-a-Sketch toys, but I havenÔø‡t tried it and it certainly wouldnÔø‡t not be a very cost effective method.
Another magnesium product is Mg ribbon. It burns like a fuse and very brightly, but it's not particularly useful, just fun. It can be used to ignite thermite, which is one of it's more common uses.
Here is something that was sent to me that could be useful:
by A J Smith
A group of alloys known commonly as "Magnalium" finds widespread use in pyrotechnic applications: it provides excellent heat and light output in numerous applications from sizzling comets to bright color compositions to "Dragon Eggs" and more. The alloy that is 50% magnesium and 50% aluminum is probably the most commonly used variety in the United States. However, alloys of other ratios have different characteristics, and are worthwhile materials for experimentation.
The history of "magnalium" alloys in pyrotechnics is unclear. We know that refining of magnesium and aluminum both became practical on an industrial scale during the late 19th century. Before this, the metals were both horrendously expensive in their pure form, because of difficulies involved in isolating them from their naturally occuring sources.
Pyrotechnists have long been a secretive lot, not inclined to share the results of their researches with the general public, and certainly not inclined to do so among their professional colleagues, i.e. "the competition." It should come as no surprise that the introduction of aluminum, magnesium, and "magnalium" powders into fireworks was not well documented as it occured. However, at least by the time Thomas Kentish published The Pyrotechnist's Treasury in 1887, fireworks makers were using magnesium in color formulae.
We also know that magnesium and aluminum powders were used in various photographic flash mixtures around this time, and that the technology of preparing and using these mixtures in photography spread rapidly around the world.
As to magnalium per se, however, the earliest reference I am aware of to this material is in a work by a Karl Gellingschein of Germany who documents its use in fireworks to produce a flash report powder or "Blitzpulver". Certain Chinese sources confirm the early uses of magnalium in flashcracker compositions very early during the twentieth century; unfortunately these sources do not indicate why or how these materials came into use for this purpose. However, we can make some educated guesses, and back these up with experimental & circumstantial evidence. Magnesium and aluminum in their pure and commonly alloyed forms are very ductile, but strong metals. This makes aluminum, for example, an excellent candidate for extrusion into wires and many other products. Magnesium, similarly, has excellent mechanical characteristics which lend it to use in applications such as casting into basic machine components such as engine components and aircraft parts.
However, when melted together and cast as magnalium alloy, the resulting product is soft, and incredibly brittle. This property of magnalium makes it practically useless for ordinary industrial applications; however, for the manufacturer of magnalium metal powder this brittleness is most useful, because it makes magnalium much easier to mill into a powder than either aluminum or magnesium. Under the primitive, field-expedient conditions that characterize fireworks amnufacture in many parts of the world, the pyrotechnist can make his own supply of magnalium with a minimal investment in materials and technology. Often, recycled materials can be used. A friend and collaborator in my research performed the following experiment to test the hypothesis that it would be practical to manufacture modest quantities of magnalium powder under conditions most primitive.
The base materials selected for the experiment were scrap magnesium of unknown origin in the form of a section of inch thick plate, a dull grey color on the outside and scrap aluminum wire. Aluminum melts at 660.2oC, and magnesium melts at 651oC, temperatures easily attained in almost any fire using any common fuel. A mass of 454 grams of the magnesium metal was weighed out on an Ohaus lab balance. 454 grams of aluminum in the form of used aluminum electrical wire, stripped of all insulation, was also weighed out on the balance; electrical wire was selected because of its probable purity relative to other common aluminum alloys. Further experiments ought to also take into account the presence of other metals present in the magnesium sample, such as aluminum (commonly present in amounts of 9% or less). Both samples of metal without further preparation were then placed in a common cast iron "Dutch oven" kitchen pot. Some Argon gas was injected into the container to limit the amount of oxygen available to the metals, although this may not have been necessary or even effective.
The experimenter then built an open, outdoor fire of scap wood and placed the covered Dutch oven in the fire. The Dutch oven containing the metal samples was heated until it was observed to have come to a "red heat" and kept hot for about 1/2 hour. After the fire had died down, the kettle was removed from the ash pile and opened. The metal samples had indeed, melted and formed a homogenous pool of molten metal alloy in the bottom of the pot, which had solidified, leaving behind limp grey ribbons of aluminum oxide, the residual coatings of the aluminum electrical wires atop the magnalium alloy sample. A peculiar aroma was present when the vessel was opened, reminiscent of Calcium carbide. Possibly there may have been unknown by-products formed during the process -- perhaps carbides, or nitrides from reactions with atmospheric nitrogen. The resulting sample of magnalium had a bright, silvery appearance.
The composition of the sample was probably slightly slanted to the magnesium end of the continuum, perhaps about 55/45 magnesium / aluminum because of the oxide content of the aluminum sample. Qualitative analysis of the sample was not available. However, pounding portions of the sample in a steel mortar and pestle revealed that it crumbled into a granular powder with minimal effort and minimal expenditure of time. The resulting powder was screened into powders of different particle size and tested for its charachteristics in several pyrotechnic mixtures. Admixture with water produced the aroma of ammonia (i.e. NH4OH), which suggests that care should be used with this material, avoiding mixtures with chlorates especially in water-based systems (e.g. stars bound with dextrin and water). Magnalium glitter made with the material had bright flashes and the characteristic sizzling sound associated with other magnalium based pyrotechnic mixtures. Dropping small quantities of the coarser powder through the flame of a propane torch also elicited the characteristic sizzling sound, and produced bright flashes of white light.
The results of the experiment suggest several conclusions. These are 1) It is practical to manufacture small quantities of magnalium metal from common scrap on a small scale with minimal capital investment. 2) The metal so produced can be utilized to produce pyro grade magnalium powders with again, minimal expense, effort, and time. 3) It would have been possible for fireworks makers a century or more ago to have produced similar magnalium type compositions and use them to develop pyrotechnic compositions. Further research seems warranted to establish whether such small scale manufacture of magnalium would be useful for amatuer orprofessional fireworks makers desiring material not commonlyavailable on the commercial market. Furthermore, the presence of impurities or by-products from this process in the magnalium produced should be assayed and reported on in later research.