Antimony Tin Alloy

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Last Post 30 October 2022
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Eutectic posted this 03 March 2022

Antimony Tin Alloy

I have recently made a second and larger batch of an antimony tin alloy. This alloy, 75% antimony and 25% tin by weight is the same ratio found in Linotype alloy. This was chosen both for reasons of utility and the lower liquidus of 1000 F which made production in a simple gas fired pot with normal flux for oxidation protection possible. The high temperature soap/fat flux I reported on in 2020 was effective.

The alloy pours freely and solidifies with a shiny surface. It is hard and brittle as expected of a high percentage antimony alloy. On fracture it produces a pronounced crystal structure. The first batch showed the blending of 75/25 alloy with lead turned out to be much easier than expected. Without any special flux, the alloy rapidly goes into solution in lead at 650F. The production of Linotype or any lead antimony tin alloy of similar composition is readily achieved.

This pathway to introducing antimony into lead alloys is much simpler than direct addition of antimony with the required special fluxes, exacting procedures, and associated dangers.

Steve

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Duane Mellenbruch posted this 03 March 2022

Thank you for the update. This is a back burner project for me. I have the material, but have just not taken the time to work it out. Your efforts are appreciated.

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Eutectic posted this 03 March 2022

Thanks Duane,

Theory predicted it should work, it is energetically favorable. However we both know nature has a way ignoring theoretical calculations.
The next question is how low a percentage of tin can be used. Tin is the most expensive component and a lower percentage is desirable for some uses.

One percent probably will not work, limited by energy and oxidation, but 10% is still favorable and may work. The liquidus temperature will increase and better flux protection may be necessary. We will see, let me know it it moves to your front burner.

Steve

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Duane Mellenbruch posted this 03 March 2022

I was looking at the ratio as being like a universal enrichment alloy. As an easier way to produce a given alloy from common soft lead scrap. Most soft lead such as plumbing probably has about 1% antimony to make it easier to produce a product. With a basic alloy of 25% tin, and 75% antimony the hobby caster could start with 96 pounds of scrap and add 4 pounds of enrichment alloy for a final alloy of 1-3+-96- which would be a good general purpose alloy. Somewhat like COWW. Reducing the soft lead basic alloy, and keeping the same amount of enrichment could result in 2-6-92 which is magnum pistol alloy. Additional concentration could result in an alloy similar to linotype. But not that many use lino for general shooting and hunting due to it being brittle.

Higher concentrations of antimony might raise the melt temp to a more difficult temperature to reach for easy alloying by the home caster. I suspect that it will not take nearly 25% tin to make antimony easier to alloy with lead at common casting temperatures.

Considering that COWW only have about .5% tin and 2.5% antimony which is a ratio of 1-5, there is some room to explore, but is that practical? There a lot of paths out into the weeds trying various methods of blending antimony with lead or tin to make a good repeatable casting alloy.

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BigMan54 posted this 03 March 2022

Thanks for the info

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

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NH_Jim posted this 21 October 2022

Does anyone know who sells the cheapest pure tin or antimony?

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Eutectic posted this 22 October 2022

Jim.

Roto Metals is my first stop. Sometimes you can get free shipping. I have not used any other dealer for many years, if there is another choice others may know.

My cheapest tin has come from a local scrap yard. Ask if they have solder, you may be surprised. No it is not pure tin but 60/40 solder is good as gold.

Steve

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Ross Smith posted this 24 October 2022

Have any of you cast a bullet of this antimony-tin alloy? My latest batch of linotype from evil bay casts bullets up to 20 gr. lighter than the previous lot. I'm wondering what it is. It casts well and the bullets are hard and shot well without leading?????????????

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RicinYakima posted this 24 October 2022

Probably not linotype, but monotype. Those folks don't know the difference.

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Eutectic posted this 28 October 2022

Unfortunately, there are several compositions for hard "Monotype" alloys, it may be as much as 28% antimony, linotype alloy is 12%.

You can add lead to the alloy to get the % antimony down and still have the hardness you need. Might be a good buy!

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Bud Hyett posted this 28 October 2022

Several thoughts:

There is an obscure "Factory" type that is harder than Monotype. I only know it has more antimony than even monotype.
The linotype printer operators often added the correction material by guess until the printer was running correctly. They were under schedule constraint to get the paper out.
I've bought used "Linotype" metal in varying hardness. I mix up a 120/140 pound batch in a large pot and then shoot it until I need more.

And as Ric stated, the seller often does not know the difference. They figure if it is hard, then it is Linotype.

Farm boy from Illinois, living in the magical Pacific Northwest

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Eutectic posted this 29 October 2022

In the early 60's I got my Linotype from the last print shop in Miami running a Mergenthaler Linotype machine. These are museum pieces now, if you want to see a good example of engineering, look one up.

After the print slugs were used they melted them in a large pot and cast them into 2 foot long, 22 pound ingots which had a eye on one end. The eye hooked onto the automatic feed which lowered it into the pot, keeping the alloy level and casting pressure constant.Neat idea!

You lose a small % tin and a smaller % antimony every time you cast and re-melt. When the casting quality went down, they added little ~3 pound ingots marked Plus Metal which had high % tin and antimony . You can only do this so many times as the contaminants slowly build up. Then they had to order a fresh batch of virgin Linotype Alloy.

I bought some Plus Metal ingots and made bullets for my 30.06. They were light and so brittle they would crack if you bent them. Accuracy was poor and they leaded the bore if pushed. Probably about like Monotype Alloy.

I learned a lot about alloys and casting from the print shop foreman. Casting type and casting bullets requires the same techniques. Virgin Linotype Alloy is amazing, I loved casting with it, I could get 99+% perfect bullets, it is addictive!

Note the part about replacing the alloy when it did not cast good type. The burned-out alloy went to the local scrap yard. Either as type slugs or the 22 pound ingots. You could buy this from the scrap yard as "Linotype" but it will cast poorly!

That is why I learned to make my own virgin Linotype after the print shop closed.

Steve

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358156hp posted this 30 October 2022

To expand on Steves post, I've seen the machines that make the distinctive print shop pigs (ingots) for sale a number of times over the years. So just because it looks like a lino ingot doesn't necessarily mean it is one.

Antimony Tin Alloy

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