USING TEMPERATURE TO SORT OUT TIN AND PEWTER

Mitty38

Seeker of knowlege
I have a hodge podge of assorted tin and pewter, plus a bunch of unmarked metal.

About 25 lb but probably 5 lb is aluminum and zinc. Some of it is mystery metal, not marked, but not soft enough to be pure lead.

My plan of attack is to start a puddle of pure tin in a large cast pot on my turkey fryer or BBQ grill. And keep that pot controlled some how, to stay between 500 and 550 degrees. Then add the other stuff a little at a time, skimming off what does not melt. Then add my 5 lbs of my already made "alphabet soup alloy" (aprox.91% tin 3% lead) to the mix. Then let it cook a while while stirring at about 500 degrees. Then flux and wax it.

My theory it this should keep the zinc and aluminum out and give me 15 to 20lb or so of a constant , nice pewter type alloy, that I can use pretty much as pure tin.
Plan on pouring it into 1/4 lb ingot, even if I have to make a mold. That way I can just drop one in every 10 lb pot for good fill out.
Am I going down the right road with this?????
 
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Brad

Administrator
Staff member
Can you identify the zinc and aluminum? The Al won’t melt at reasonable temps but the zinc can. I would personally not add anything that might be zinc just to eliminate and chance.
 

Mitty38

Seeker of knowlege
The aluminum not so much worried about. Not even going near half its melting point.
ZN melts at ~700 deg. Thru my work experience, I have known it to chemically bond or become reactive under the right conditions to slightly<600 deg. But this takes more then a few minuets to happen.
I am thinking by keeping temps below 550, and keeping time in the pot, for metal that does not melt, to well under 5 minuets, I should be ok. That this would be a viable way to keep unwanted metal out of my alloy.
I could be wrong, never went there.
Kinda hoping to see if someone has already tested my theory.
Before I toss any metal I bought, that may or may not be tin or pewter.
 
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Brad

Administrator
Staff member
People have used a similar method to eliminate Zn wheel weights. If it floats for long on 5-550° melt then skim it and toss it.

As long as you keep a close eye temp you should be fine.
 

Mitty38

Seeker of knowlege
People have used a similar method to eliminate Zn wheel weights. If it floats for long on 5-550° melt then skim it and toss it.

As long as you keep a close eye temp you should be fine.
Kinda of what I an thinking, keep temp as low as possible and limit time in the mix for anything that does not melt into my puddle right away. Figure I will just have to be very vigilant.
 

fiver

Well-Known Member
zinc is 787.
unfortunately tin likes zinc so much that zinc is used to reclaim tin from scrap lead alloys.
they drop the lead alloy in a sheet [waterfall] and shoot the zinc through it and it scrubs the lead out of the alloy that quickly.

I don't know how they strip the tin from the zinc though,, unless they oxide it out.
 

Mitty38

Seeker of knowlege
zinc is 787.
unfortunately tin likes zinc so much that zinc is used to reclaim tin from scrap lead alloys.
they drop the lead alloy in a sheet [waterfall] and shoot the zinc through it and it scrubs the lead out of the alloy that quickly.

I don't know how they strip the tin from the zinc though,, unless they oxide it out.
That is why I put in the ~ (approximately sign)Knew it was a tad over 700, from working with it at work. Just too lazy to google it in mid post.
Just won't cut me no slack, will ya.;)
 
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Bret4207

Undesirable member in absentia, Northern NY
FWIW, some of the WW I've dealt with are marked "Zn" if they are Zinc. Some, not all. If it's in unmarked non-WW form, I've found a simple scratch test against a known tin or lead alloy is a pretty good indicator. Kevins Acid idea is said to work to.
 

fiver

Well-Known Member
the point is melt each suspected piece individually.
there is a metal out there called white metal it looks and acts like tin until you put the heat to it then it just poofs off like smoke for the most part.
it will mix in readily to a tin or lead alloy and make your day miserable. [it's like adding calcium]
anyway it's the stuff they make that cheap fake county fair skull ring type jewelry from.
 

Mitty38

Seeker of knowlege
Had to look up white metal. Cadmium bismoth and zinc is one combination of it. I could see where that could mess your alloy up real quick.
 
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Ian

Notorious member
"Zinc" WW aren't pure zink. They're a castable alloy, likely Zamak #3 or similar which has a lower melt point than pure zink, like around 650⁰F.
 

fiver

Well-Known Member
I think the pile of it I have does melt around 700 or thereabouts.
I mostly use it as a lead alloy additive and haven't paid much attention to where it melts more like what the little blobs I make from it weigh.
 

Mitty38

Seeker of knowlege
So I see where the melt at a low temp, and scrape off method may work ok for wheel weights.Or at least in the situation of known possible alloys.
But maybe not so good of an idea for pewter and zinc looking mystery metal that is not marked.
 
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fiver

Well-Known Member
if it ain't marked I don't trust it.
and I definitely would not try to add it directly in a good pot of tin or casting alloy.
 

Mitty38

Seeker of knowlege
Well there is always a need for sinkers. Think I will sort out the mystery metal, and just melt it down together for sinkers. As I tend to loose a lot of those, now that I am fishing for catfish again. Might just save myself a few headaches.
Figure why get lazy and stingy, then mess up a lot of good material, when at least for me, it is so hard to come by.
 
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fiver

Well-Known Member
exactly.
for normal target type stuff like your 38 you probably don't even need to add in any tin if the alloy casts well as is.
it isn't necessary,, it is helpful when needed.