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Correctly identify Aluminum, smelting brass Answered

 How can I correctly identify aluminum?  Aside from the weight, how do I find out if it is pure or some alloy that will make make even the vultures drop dead when smelted. Owing to a project I'm working on where I wish to cast letters in aluminum for a wind harp, I have been on a search here on the farm. Have found literally 200kg of scrap brass and and about 35g of aluminum! The letters have to be out of aluminum for rust reasons.

2nd Question

Does zinc alloy aluminum rust in the same fashion?

3rd Question

Brass. I haven't researched it yet, but could anyone give me a clue as to smelting the stuff?



AVOID brass like the plague - a lot of it contains lead.
BRONZE is good though.


8 years ago

I tried melting/casting brass with my micro aluminium forge (back before I had to work for a living).  The zinc burnt off (pretty blue flame), and what was left was a horrible lumpy slaggy mess.  That wasn't even a very hot forge.

Your forge wasn't hot enough and what was left was contaminated by oxides. Run a hotter forge, add extra zinc after the scrap has melted ( I use sacrificial annodes from boats as they are pure zinc), use a lid on your crucible and cast in a well ventilated area

Aluminum does not rust red like iron, but will sometimes corrode to a white powder which usually sticks hard to the metal and seldom causes real structural damage. Beyond that, best guesses will found by using Lemonie's tables and link to figure which alloy would have been used for a given application.

2nd answer
Aluminum-Zinc alloys may produce a greater amount of whitish powder, and be more damaged by the corrosion; but it'd be a tough call to make a field ID on that.

3rd answer
To smelt scrap brass:
  1. Put all the scrap in the back of your truck or ute.
  2. Drive to your (probably not-so-local) brass smelter/refiner that handles small private lots, which you found by googling "brass smelter 'oakeyville.' "
  3. Say to the nice man at the gate "Good day, sir. I would like to sell you this lovely 200 kg of scrap brass."
  4. Take the money the nice man gives you and buy enough aluminum foil (shop for the best price/unit weight) for your project. Al foil is very nearly pure aluminum and is likely the best source for this sort of small-scale project.
  5. If you choose to turn any remaining scrap-brass-sale funds into beer, please make that a separate event from the return drive home.
Hope this helps - good luck with your project!

Thanks Gorfram, your humor always makes me smile !
I had never thought of the tin foil route - which is always so nice and - woo - shiny ! If it's made up of aluminum then why on earth is it's generic name tin foil anyway?

Rest assured that in the event of option 5 being exercised, they will be aluminum tins!

You said 'Lemonie's tables'. Did you mean the link he presented, or the tables created by Lemonie and then he gave me the link?

1.  I'm glad to know that there are at least two of us who enjoy my humor. :)

2. Tin foil and tin cans are are made of aluminum because -
Way back when in the late 19th century when they first came into widespread manufacture and distribution, they were made of tin. Tin was comparatively cheap, while aluminum was vanishingly expensive.

Aluminum is very difficult to refine by the methods known at the time, and was rare and precious. Then in 1890-something, a couple of guys figured out a way to refine aluminum very cheaply by applying largish amounts of electricity to the reaction.

Over the next several decades, aluminum became widely and inexpensively available; while worldwide tin resources were rapidly becoming depleted, with the rise in price that supply-&-demand economics would lead you to expect.

By the last quarter of the 20th century,  machinery and manufacturing processes had been fully converted to "tinning" everything in aluminum or (in cases where aluminum isn't strong enough) in steel. If you find a tin can that's actually made of tin, it's an antique that's probably worth a couple of bucks at a dealer's. Tin foil made of tin is worth many antique-dealer bucks, but was very fragile stuff and unlikely to have survived.

It's also a little bit of one of those "separated by a common language" things: American cats (like the one currently trying to block my view of my monitor :) are often fed canned cat food; while cats who must share their soveriegnty over their subjects with HM Queen Elizabeth are more likely to demand and receive tinned cat food.

3. I meant the tables in the links Lemonie gave, which is not really what I turn out to have said at all (oh, to be able to edit one's posted commments).

For instance, if you have what looks like a cast aluminum water tank, it's proabably the alloy listed in the tables as used for casting of tanks. If you have a welded aluminum tank, it's proabaly the weldable alloy listed for tanks. It's a limited sort of bass-ackwards reverse engineering, but is probably the best you can do outside of chemical or x-ray analysis.

Thanks Lemonie, you are always there with your time and knowledge for us lesser mortals. The effort is very much appreciated.

Someone asked a similar question earlier this year, I remembered that information was out there somewhere.