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Discussion Starter · #1 ·
What does zinc look like in a lead melt?

I was rendering down some stick-on wheel weights for ingots and ended up with a condition that looked similar to “oil on water” to me. Silver colored metal floating on top of silver colored metal.

I was able to pour lead “under the other metal” to the ingot mold to get by most of this.

What was I looking at?

Cheezywan
 

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Put a drop of pool acid on your ingots.

If there is zinc contamination, it will sizzle. If there is no zinc in there, no sizzle.

BTW, lead can take up to around 2% of zinc will little/no adverse casting effects. There is also a thread on the castboolit website where people have used sulphur to remove zinc from a contaminated alloy. Not sure I would do that though, as sulphur can be a pretty nasty chemical to deal with.
 

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The oily appearance was likely from the adhesive on the weights. Was the floating metal liquid or solid? It was most likely just tin/antimony. I know stick ons are said to be pure lead but i have used them and experienced the same thing and i simply fluxed it and made bullets. There is a couple of photos in the lyman cast bullet handbook showing what zinc looks like when mixed with lead.
 

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. . . BTW, lead can take up to around 2% of zinc will little/no adverse casting effects. . .
I've never tried the experiment, but Richard Lee in Modern Reloading insists as little as one part zinc in ten thousand (0.01%) can ruin an alloy for casting. Do you have a link to a thread by people who've actually tried this, or have you tried it? It would be interesting information to have around, even if it is conflicting.
 

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I've never tried the experiment, but Richard Lee in Modern Reloading insists as little as one part zinc in ten thousand (0.01%) can ruin an alloy for casting. Do you have a link to a thread by people who've actually tried this, or have you tried it? It would be interesting information to have around, even if it is conflicting.
Just second hand info from people on the CB website.

Thankfully, i've never got zinc-laden lead and I'm not in a hurry to try it! :D
 

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Discussion Starter · #6 ·
I looked at the picture on page 44 of the Lyman Cast Bullet Handbook. Is similar (though difficult to tell if is the same as) to what I was looking at.

Was NOT adhesive. That burned off as expected.

My procedure was to sit and sort clip-on weights into the pot, stick-ons into a separate bucket, and trash to yet another.

My yield of bullet metal from clip-ons was near 160 lbs. No problems at all!

Last melt on Sunday was the stick-on bucket. This was when I noticed my above posted symptoms.
I have about 25-30 pounds of this “suspect metal” and a dry gas pig at this point.

Re-fill the pig, read the posts is my plan for now.

Thanks all for reading and posting.

Cheezywan
 

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What Zinc seems to do, even in pretty small amounts, is increase surface tension. Even hot-hot, the melt just won't fill the mold out worth a hoot.

My best advice is to try to cast some bullets with that melt, something with nise sharp corners like a Keith style SWC or a Loverin style rifle bullet... and if it looks like an eroded, chewed up dog toy, the contaminate was probably zinc.
 

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My best advice is to try to cast some bullets with that melt, something with nise sharp corners like a Keith style SWC or a Loverin style rifle bullet... and if it looks like an eroded, chewed up dog toy, the contaminate was probably zinc.
But wouldn't that run the risk of messing up your casting pot?

Heck you used to be able to get 2 gallons of pool acid for $8 and i'd rather spend $8 than tear my casting pot all apart because it was fouled with zinc.
 

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Have only had the problem once. Gave up on bullets and cast a pile of deep water fishing weights. emptied the pot, cleaned the pot, and have been using it just fine with good alloy. (fish don't seem to care that my sinkers have rounded corners).
 

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Discussion Starter · #10 ·
My original intent was to cast this “near pure” lead into 54 caliber round balls for a friend.
No sharp edges to worry of on a round ball. I do worry of ballistic performance for my friend though!
“Easy way out”, is to cast it into fishing sinkers. I have other “near pure” lead for my friend to shoot. I’m only looking at 20-25 pounds of this suspect stuff after all!

Personal hero of mine (Al Gore) would want me to recycle this stuff I think? I’m leaning toward sling-shot ammo or fishing sinkers at this point. I really don’t mind cleaning my casting pot if I can help his cause (to stop waste).

Three day weekend coming. I hope to re-melt the whole 20-25 pounds and have another look at it. “Play” over labor day is on the menu.

Thank you for your replies all,

Cheezywan
 

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Put a drop of pool acid on your ingots.

If there is zinc contamination, it will sizzle. If there is no zinc in there, no sizzle.

BTW, lead can take up to around 2% of zinc will little/no adverse casting effects. There is also a thread on the castboolit website where people have used sulphur to remove zinc from a contaminated alloy. Not sure I would do that though, as sulphur can be a pretty nasty chemical to deal with.
What is pool acid?
Can you get it at Wal-Mart?

Michael Grace
 

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It is called muriatic acid in the hardware, where it is sold for swimming pool cleaning, but to any chemist it is hydrochloric acid, HCl.


Cheezy,

If you have Richard Lee's book, Modern Reloading, he has a section discussing their round ball and Minié ball loads. A couple of points he makes are worth noting. One is that lead you can mark readily with your fingernail is soft enough. Lead requires higher melt and mold temperatures to fill adequately, and he recommends heating lead until the thin surface oxide layer takes on a purplish cast.
 

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I thought I had a bad zinc batch a while back. I melted some of it in a small pot on a Coleman stove and laddle poured a half dozen bullets. No problems so I guess it was just funny looking lead.
 

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Discussion Starter · #15 ·
I got home early today. So I took the time to re-melt this whole suspect batch. Cast to a Lee ingot mold. Stirred and skimmed before each pour. No flux.

First pour was to pre-heat the ingot mold (returned to pot after second pour).
A few observations:

The deep spots in the one pound cavities of the mold “caved-in” as the metal cooled.
There was a sort of “curd” on top of each pour (despite the freshly skimmed and smoothly poured melt).

Fine details of the ingot mold are good (LEE).

I took a little “persuasion” to get the ingot to exit the mold (just a light tap on the concrete).
Dull “thud” when it landed (no “Ting”).

This "stuff" is going to be fishing sinkers from my view. I cleaned my "ingot/smelting pot .

Unclenick,
I have read Richard Lee's first book. I understand about the higher temperature of pure lead. Nothing but the "best" for the few friends that I have though! Sling-shot ammo maybe?

This stuff is garbage for my purposes.

Cheezywan
 

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Discussion Starter · #16 ·
It really doesn’t surprise me much. Ribbonstone’s take on the situation was about right on the nose.

I casted the whole lot into ½ ounce walking sinkers. I found that if I casted hot and fast, I got near a 30% rejection rate. The rejects had a void near the “toe” of the sinker (which is the most massive section and is high in the mold). I tossed the rejects back in the pot and re-cast them.
All in all, I got some good sinkers.

I figure to gift them back to the guys that work at the tire shop that gave me the weights. Might pay dividends in the future?

I gave my Lee pot a good scrub too. Then boiled water in it. Flash dry. Spitz with WD-40. Good to go for next time.

I think I learned what zinc looks like in a melt!
Thanks all.

Cheezywan
 

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Discussion Starter · #18 ·
It never hurts to be a nice guy.......

I get "hurt" real regular qajaq. Getting used to it.

Pool acid. I need some of that. I have a buttload of sinkers to test. Not going to buy it though!

Don't care much since my "bullet metal" is good (safe).

Lot's of you folks put thought into my question.

Thank you.

Cheezywan
 

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I looked at the picture on page 44 of the Lyman Cast Bullet Handbook. Is similar (though difficult to tell if is the same as) to what I was looking at.

Was NOT adhesive. That burned off as expected.

My procedure was to sit and sort clip-on weights into the pot, stick-ons into a separate bucket, and trash to yet another.

My yield of bullet metal from clip-ons was near 160 lbs. No problems at all!

Last melt on Sunday was the stick-on bucket. This was when I noticed my above posted symptoms.
I have about 25-30 pounds of this “suspect metal” and a dry gas pig at this point.

Re-fill the pig, read the posts is my plan for now.

Thanks all for reading and posting.

Cheezywan
Some of the stick on weights are zinc alloy. But they're easy to spot from the lead ones. A hammer will tell you which are which. The lead ones are pure lead (or **** near it) Hydrocloric acid isn't the only thing that'll eat zinc. Sea water will as well, just not as fast. Zinc has been used for anodes on ships and boats for years. Aluminum is now used for this too.
 

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Discussion Starter · #20 ·
Some of the stick on weights are zinc alloy. But they're easy to spot from the lead ones. A hammer will tell you which are which. The lead ones are pure lead (or **** near it) Hydrocloric acid isn't the only thing that'll eat zinc. Sea water will as well, just not as fast. Zinc has been used for anodes on ships and boats for years. Aluminum is now used for this too.

Interesting about the anodes for salt water. I'd forgotton about that. I will drop a sinker in salt water and observe it for awhile.

I've been reading some interesting stuff on the web about this. Some kinda dangerous. Sinkers was the safe way out. I still gained some good bullet metal.

Thanks for the thought.

Cheezywan
 
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