lead ingots?

[bear58]

The other day a friend gave me about 50 lbs of ingots for helping him out. The ingots look dull and frosted. Along with the ingots were a couple lbs. of COWW'S. Some of the WW are zinc. I have a hunch that the ingots were smelted with the zinc not removed. Is there a way to confirm this?

[pworley1]

Just being frosted doesn't necessarily mean it has zinc in it. I would melt and flux a few, cast some bullets, and see if they fill out the mold well. If they do then go ahead and use them.

[Foto Joe]

If the person who smelted the ingots didn't have the pot turned up to the "Surface of the Sun", chances are that the zinc floated to the top and got skimmed with the clips. Melt a few down and if they don't look like oatmeal when melted at 700-750 degrees then you're good to go.

[Springfield]

Go to the hardware store and buy some Muriatic acid, in the pool supply area. Drip some on an ingot and see if it fizzes/bubbles. If it does there is zinc in there. If not, then not, or at least not enough to worry about. Most ingots come out dull gray, it depends on how hot the lead was when poured.

[bear58]

I guess it looked a lot different than my ingots in appearance and color along with the zinc WW in the box. I've been very careful to cull out the zinc when I separate my WW's. How critical is zinc contamination in you melting and smelting pots?

[Foto Joe]

Ever since I started smelting COWW's I've been EXTREMELY paranoid about zinc contamination, the last thing I need is a door stop. My paranoia was found to be unwarranted when helping a friend last weekend smelt a few dozen pounds of COWW's. As it turns out he missed two zincs and a steel in his sorting and all three popped right up to the surface. The smelting pot was running at around 750°. According to the Information Superhighway Zinc melts at 787°. If you keep your temperatures reasonable when smelting you shouldn't have a problem.

[Jeff H]

.........How critical is zinc contamination in you melting and smelting pots?

You just really don't want any in there at all if at all possible, period.

It makes your life miserable and causes you to question everything from your own casting prowess, the methods you employ, the quality of your tools to the way you were standing and how you were holding your mouth when you filled the cavities. You could end up changing all your variables one by one to eliminate the problem only to feel like you should just sell your casting stuff. I didn't sell it but I sure thought about it.

I have some alloy still that I believe has some amount of zinc in it and I do still use it but I know that when the bullets don't come out perfect that it's not me, it's not the mould,.... I only shoot those where I know I or someone else won't be trying to recover the lead. I got away from casting when I went into the military and it was one of the first things I started doing again when I got out. I didn't know about zinc being a problem back then but I figured it out the hard way. All my casting before that was under the watchful eye of two crotchety old casters. When I was on my own and living far away, I didn't have one of them to warn me and got my first self-taught lesson in casting.

It pays to take the time to pick them out and to keep questionable alloys separate. It's most critical when smelting because that's when it's introduced and you mess up bigger batches. If you throw a contaminated one-pound ingot into a ten pound casting pot, you've only compromised ten pounds at the most. If you suspect you have contaminated your alloy, do NOT try to dilute it by throwing good alloy after bad. If you weren't looking for it or didn't see it smelted, you won't know just how much zinc is in it.

[cali4088]

You wont get good pours with zinc in your lead. If its dull and frosted over, that means it has a lot of antimony in it. If its frosted over and shiny, it has a lot of tin in it and was poured at a high temperature.

Melt them, get the temperature really high, DO NOT SCOOP SCUM YET, FLUX FIRST, then clean. Lower temp and pour more ingots or cast. Problem solved.

If for some reason you melt and oatmeal floats, scoop scoop scoop. Make sure to have temp below 675. preferably at around 600 since leaded alloy melts at a lower temperature

[cali4088]

Ever since I started smelting COWW's I've been EXTREMELY paranoid about zinc contamination, the last thing I need is a door stop. My paranoia was found to be unwarranted when helping a friend last weekend smelt a few dozen pounds of COWW's. As it turns out he missed two zincs and a steel in his sorting and all three popped right up to the surface. The smelting pot was running at around 750°. According to the Information Superhighway Zinc melts at 787°. If you keep your temperatures reasonable when smelting you shouldn't have a problem.

Sounds like you came close to disaster. COWW melts at a really low temperature since its alloyed and not pure lead. I smelt around 50 lbs of wheel weights at a time in my skillet. I turn the turkey fryer on high and as they melt i keep pushing down on the pile of COWW. even though the turkey fryer is pumping, the melted lead on the bottom is constantly cooled by the non melted lead being pushed down and never reaches more than 600 IMO. As the clips are separated i take them out. I turn the zinc WW in for 30 cents a lb at the my local scrap yard. As soon as all the lead is melted, i turn down the heat and take all zinc WW out. Its pretty easy

[bangerjim]

You just really don't want any in there at all if at all possible, period.

It makes your life miserable and causes you to question everything from your own casting prowess, the methods you employ, the quality of your tools to the way you were standing and how you were holding your mouth when you filled the cavities. You could end up changing all your variables one by one to eliminate the problem only to feel like you should just sell your casting stuff. I didn't sell it but I sure thought about it.

I have some alloy still that I believe has some amount of zinc in it and I do still use it but I know that when the bullets don't come out perfect that it's not me, it's not the mould,.... I only shoot those where I know I or someone else won't be trying to recover the lead. I got away from casting when I went into the military and it was one of the first things I started doing again when I got out. I didn't know about zinc being a problem back then but I figured it out the hard way. All my casting before that was under the watchful eye of two crotchety old casters. When I was on my own and living far away, I didn't have one of them to warn me and got my first self-taught lesson in casting.

It pays to take the time to pick them out and to keep questionable alloys separate. It's most critical when smelting because that's when it's introduced and you mess up bigger batches. If you throw a contaminated one-pound ingot into a ten pound casting pot, you've only compromised ten pounds at the most. If you suspect you have contaminated your alloy, do NOT try to dilute it by throwing good alloy after bad. If you weren't looking for it or didn't see it smelted, you won't know just how much zinc is in it.

Yes.......please avoid Zn if at all possible: visual sorting, sounding, inspection B4 the melt.

But-------"the sky is falling"------is NOT the scenario, if you do have Zn in small amounts!

An Experiment
I intentionally contaminated 4# of pure (with 1% Sn in there) early last year with 1, 2 ,3 ,4, and 5% Zn incrementally just to see what it would do in casting. Not really that much. As the % got higher, fill out got a little goosy because Zn RAISES the surface tension. Adding some more Sn solved the problem because Sn LOWERS the surface tension. But Sn is expensive! Zn will also lower your boolit weight a bit.

But you do NOT need to throw out 50-100# of lead or make door stops because you may have a 1 or 2 oz zinker accidentally melted in there. I bought a HUGE 110# piece of "poured in a hole in the ground" lead (COWW's I know) many months ago at a yard because somebody had thought a bit-o-zinc had "ruined their melt". No big deal. Lead cleaned up perfectly by just keeping a good eye on the re-melt temp and scooping the oatmeal off & saving it. Fluxed/reduced the rest as normal. Then later I fluxed that oatmeal with sulfur to remove the Zn (and Sn & Sb) to get pure Pb...almost 6# of it. Made some really nice ingots that melt and cast/alloy perfectly. Just be warned.....sulfur is really nasty when it burns! Get it at your plant stores.

So, do not be afraid of the bad old zinc monster! There are ways to tame it, even after the smelt.

But do everything you can to prevent it in the 1st place!

bangerjim

[mikedp]

Or the short answer might be to simply ask your friend if he separated the zinc ones. If he says yes...you're good to go. If he has that "lost" look...then you have your answer.

[bear58]

Problem is that his son smelted it years ago and he's not sure how or if he even knew to stay away from zinc. My only indications that there may be zinc in it is it looks a lot different (color and appearance) than any that I smelted or any that I have bought from members on this site. It may be totally unwarranted but just wanted to see if you all had a way to test it or get rid of it during a re-smelt.

[bangerjim]

Read my post above about removing Zn from lead.


How hard are they? WW's will be around 12. If they sort of have a "ring" when you hit them with a ball peen hammer, they are hard(er). If they have a dull thud, they are most likely pure lead or close to it.

Lead can be all colors of the rainbow and textures can vary depending greatly on melt temp when cast. Sounds like you have Sb in there, which you should with WW's.

You can either use a hardness tester or the artist pencil test as described in a thread in lots of detail on here. Pencils are ~$12/set. A good tester is ~$150 or more.

Re-melt a small portion and re-cast yourself to see if it looks like you want when YOU do it. It will NOT harm your pot. Just melt a few # and try it! That is the only way to know, other than taking one to a scrap yard in Tucson and having them shoot it with their X-ray metal gun to tell you what is in actually there. Some will do it for free, some won't. The ones here in the Valley do it for free.....if you are buying something at the time!


Good luck. And don't fear the Zn monster!

banger

[bear58]

Thanks banger. I'm going to give it try. Thanks every one else who commented. I don't think I would be having anywhere close to the success a newbie could expect without the knowledge that exists on this site.

[Foto Joe]

Ain't that the truth.

[lwknight]

Banger, I mixed zinc with some lead and tin for a test too. I forget how much of what though.
Anyway, when poured up it was soft like pure lead. After 2 or 3 days it was pretty hard. Then
after 2 or 3 weeks it was hard like rock and brittle as well.

I did have a thick sludge on top and I skimmed it off then poured up several times. Every time was the same till finally the sludge began to subside. That's when I did the time/hardness check.

[bangerjim]

Banger, I mixed zinc with some lead and tin for a test too. I forget how much of what though.
Anyway, when poured up it was soft like pure lead. After 2 or 3 days it was pretty hard. Then
after 2 or 3 weeks it was hard like rock and brittle as well.

I did have a thick sludge on top and I skimmed it off then poured up several times. Every time was the same till finally the sludge began to subside. That's when I did the time/hardness check.

I don't have any data on what a eutectic alloy of Pb/Sn/Zn would do over time! There is a lot of published info on LASC about hardness changing with time and I take that into account when I mix my alloys. Pure Zn is brittle. But what it does combined I have not real data. And I doubt anyone with our habit has done any research, because we always try to avoid Zn like the plague!

If anyone has any info, please post.

banger

[felix]

By definition, an eutectic alloy (of any number of components) will have zero change over time. The question always remains, do you have lab grade alloy? If not, then you can expect changes. ... felix

[blackthorn]

You might want to try dropping a bit of Muriatic acid on top of one of the suspect ingots. If it fizzes---you got Zinc. You can get Muriatic acid from a pool supply store.

[bear58]

Yes, I tried the muriatic acid and got no snap, crackle or pop! Thanks Springfield and blackthorn for that tip. Tried it on a zinc WW that I had and sure enough, instant fizzle. When the reaction stopped it turned dark gray. Sound right?
Thanks again for all's help with this. Feel free to continue this thread with the wealth of knowledge. I know I'm learning a lot.