How do you tell the difference between White Metal and Aluminum?
Zoins
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There was a post by Bill of CoinPeople.com indicating the Elder Ericsson medal was struck in both white metal and aluminum.
How do you tell the difference between white metal and aluminum? Would an XRF gun work?
What I've generally read is that there isn't a good definition of what goes into white metal, and that it may have tin.
https://www.coinpeople.com/topic/25153-thomas-l-elder-store-cards-and-medals/
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Weight?
My impression is both are pretty light.
Do you know which one weighs more? Is there a reference on the % difference.
My guess is the white metal.
I think of white metal as any number alloys of pewter containing tin, zinc, lead, and perhaps some copper. Aluminum is very light in weight compared to white metal so weighing it and a specific gravity test should give you your answer.
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Nice. Thanks! An XRF gun should be able to identify metals other than aluminum.
I was surprised that this issue above only had 3 struck in white metal and 153 in aluminum. I never thought of white metal special that way, but now I'll have to keep an eye out for it!
Technically "density", not weight. Or, "specific gravity" as I hear Insider2 in my head.
An XRF could tell as aluminum should be mostly pure and "white metal" is an alloy.
If they are cataloged in both metals, there should be a weight difference. But it may not be known for scarcer medals. It can be hard to find accurate reference weights for some medals.
Good info. Thanks
Recently someone asked why a museum would want to crack out a PCGS protected collection donation, and what I've heard from others is that museum collections may do this to support research like using XRF guns and measuring weights.
the term "White Metal" seems to be a catch-all for any non-aluminum alloy that is white/gray in color. I have seen it referenced as Tin, Pewter and something that the describer most likely couldn't identify. until around 1870 most white/gray medals are in fact white metal of some kind, but then aluminum started to become the choice for issuers.
weight is the best way to discern the alloy, but aluminum is really the only thing that is certain. if you don't have one of each and a known weight of an aluminum medal it can be difficult to sort out. as PerryHall said, specific gravity would work best.
also, aluminum doesn't tone, so if you have a very light medal with color it's a good bet it's white metal.
You should be able to use the XRF through the plastic. Weight and density would require removal from the plastic.
Zions- an XRF should do the trick. But ‘white metal’ seems to be the default term applied often. Unless it’s so obvious that it’s aluminum- like this:
IMO.
White metal is usually porous from being cast. As stated above it is made from many different types of metals in a combination form. It can be very brittle and damaged easily.
Aluminum is a widely used true metal. It has strength and has some flexibility to it in thin sheets.
It has a manufacturing process in which it is tempered and rolled. It can be shaped and bent into a form without breaking where white metal will break.
They do have different weights. Again in my opinion, the white metal should be heavier than the aluminum which is used in manufacturing due to its lightness and flexibility.
Hope this helps.
Wayne
Kennedys are my quest...
Appearance, sound, weight, strike characteristics & age (the broad scale use of each has a very short serious crossover time frame). In viewing and attributing hundreds of thousands of AL, WM, PT, LD and related metals I have never had to go beyond the aforementioned elements to determine AL from WM.
If you still can't tell after judging the aspects noted above, An XRF gun would be preferred over a specific gravity test. White metal has a nasty tendency to be affected quickly by moisture and retains the same due to the porosity so make sure the piece is thoroughly dry after testing.
White metal is denser (heavier relative to the size or volume of the piece) and feels more substantial. When aluminum is used for a coin or medal, it feels like cheap play money. I am not a fan of either, but given the choice, I’ll take white metal. Aluminum is better than plastic, but that’s hardly a complement.
You don't need water to do specific gravity. You could use an organic solvent.
As I said in the article, Elder’s “White Metal” is basically Tin. I give the specific gravities.