Zinc contamination question...

[EVR]

A question. I looked but did not find...

I've read that if there is any zinc in a melt, the pot itself is ruined even if the melt is thrown away.

1} I can hardly see how a pot full of contaminated lead, if dumped, would ruin the next melt, but then, if I was so sure, I wouldn't be asking this question.... :)

2} So the next question would be similar. Can a contaminated melt ruin a mold?

Thanks, guys.

Amazing site here.

[rancher1913]

the zinc eats the metal that the pot is made from. there is a video of somebody using a pot to melt pure zinc and it took out the bottom of the pot.

if dumped and scraped down and inspected, I would keep using the pot.

[upnorthwis]

While I've only been on this forum for six years, I've never heard of ruining the pot or mold with zinc. Years ago, before knowing better, I melted the occasional zinc WW in with the lead ones. Was wondering why I had to submerge them and turn up the heat to get them to melt. Been using the same pot and molds for 30 years with no problems.

[reddog81]

Seems like Bull Snot... Where did you read this? People have purposely cast pure zinc bullets without any of the issues you are asking about.

Don't believe everything you read. People make up stuff all the time, especially regarding firearms, ammo, reloading, bullets, etc.

The bottom of an aluminium pot will fail smelting lead if it gets too hot or the lead weight is too much.

[JonB_in_Glencoe]

EVR,
Welcome to the forum.

I wouldn't worry about "some" zinc in your alloy, in regards to ruining your pot.
I won't ruin your molds either.

A small percentage of Zinc in a lead alloy will actually be castable (at a bit higher temp) and will harden your alloy a small amount.
I did a test.
https://www.artfulbullet.com/index.php?threads/zinc-in-small-percentage-in-bullet-alloy.589/

If your Lead alloy is contaminated with more than 2% zinc, your will get the "Oatmeal" and your castings will be substandard at best, but I suspect you won't even able to pour any castings.

[RED BEAR]

I actually melt the zinc ww for my shotgun . I also use the same pot for melting the ww and scrap that i cast with. Use lee 20 lb ladle pot there are a couple of nuts and a couple screws that hold the pot in place so after smelting the nasty stuff just take pot off and sand with wet dry paper then clean it with break cleaner and put it back together. Good as new. Doing this for years. Just started using hot plate $10 and ss pan from dollar store to do nasty stuff so i can cast while it melts.

[EVR]

Thanks to all for the posts here. Very interesting and helpful stuff!

[wmitty]

Rancher 1913

Could the pot used to melt the zinc have been made of aluminum? I use an aluminum skillet to melt clip on wheel weights ( I know it’s dangerous) but zinc requires more heat so aluminum might fail.

[JM7.7x58]

[QUOTE=RED BEAR;4622391]I actually melt the zinc ww for my shotgun . I also use the same pot for melting the ww and scrap that i cast with. Use lee 20 lb ladle pot there are a couple of nuts and a couple screws that hold the pot in place so after smelting the nasty stuff just take pot off and sand with wet dry paper then clean it with break cleaner and put it back together. Good as new. Doing this for years. Just started using hot plate $10 and ss pan from dollar store to do nasty stuff so i can cast while it melts.[/QUOTE
You scared me a little bit. I have been in the welding trade for over 20 years and had always been taught to never do any type of hot work around either chlorinated brake cleaner or Freon. The danger is phosgene gas. Well turns out that I was over reacting, there has to be argon present for the chemical reaction to occur. Be careful out there everyone. There are weird combinations out there that can hurt you.
Here is a quote from the web.
“The active chemical in the brake cleaner is tetrachloroethylene. When this chemical is exposed to excessive heat and the gas argon, which is used in MIG and TIG welding, it produces phosgene. Phosgene gas can be fatal with a dose as little as four parts per million: basically a single small puff of smoke.”

[rancher1913]

Rancher 1913

Could the pot used to melt the zinc have been made of aluminum? I use an aluminum skillet to melt clip on wheel weights ( I know it’s dangerous) but zinc requires more heat so aluminum might fail.

I just remember seeing a thread on here about somebody ruining their pot using pure zinc, the reason they gave was some kind of reaction to dissimilar metals, they even linked a video.

[RED BEAR]

Thanks for the concern but i use the break fluid on cold pot or molds only then let it dry before any heat. I realize somethings don't mix learned a lesson about melting battery lead. Didn't think i was going to get out of my garage. More carefully about things i use.

[RogerDat]

Thanks for the concern but i use the break fluid on cold pot or molds only then let it dry before any heat. I realize somethings don't mix learned a lesson about melting battery lead. Didn't think i was going to get out of my garage. More carefully about things i use.
Funny how much we ALL learn over the years from breaking stuff, causing ourselves pain, and the occasional running from danger. Lord knows a whole lot of stories start with "one time I was...." and end with "was lucky". First one came to mind was cinder block stands for working on cars.

I think it is fairly standard procedure to clean new molds with brake cleaner to remove the lubricant used in cutting them. Sounds like it might be prudent to do that brake clean spray before the toothbrush and soap and water cleaning. Even if in the normal situation not involving mig/tig welder one won't have argon for a reaction.

BTW - what do you cast for shotgun from zinc? Waterfowl shot?

[fredj338]

I have had contaminated alloy before but it takes a lot more than 1 zinc ww in say 20# of alloy to cause a problem. I doubt zinc hurts iron or steel they use zinc coatings to preserve steel exposed to elements.

[RED BEAR]

It is my understanding that 1or2% zinc doesn't hurt anything.

[fredj338]

It is my understanding that 1or2% zinc doesn't hurt anything.

I got some 15# blocks of alloy from a friend that melted down ww. He did not understand they zinc thing & when I dropped one of these into my 40# magma, it froze the pour spout up. I tunred it to max heat & fluxed the poop out of it, removed maybe 1# of dros & it settled down. I have no idea how much zinc was in that 15# block but after adding more good alloy after fluxing, it was diluted enough to cast. I remelted the other blocks & fluxed them heavily. I was able use all 60# worth.

[lightman]

I have real doubts that zinc will hurt a pot or a mold. I've melted zinc in a cast iron pot for other purposes and have not noticed anything. As far as bullet alloy, I just plain don't want any zinc in my lead. None! I'm sure I have missed a zinc weight or two and that most of us have too. But I strive for zero! Some test have shown that a small% won't hurt. I seem to remember that a member that doesn't post much anymore did some test and that he found that 5% or less will still cast ok.