ARRGGHH, I Think I've Been Zinc'd!!

[Foto Joe]

Let the chuckles and "I told you so's commence." A few months ago I picked up about 30 pounds of lead from eBay, the price was comparable to sorting and smelting my own so I figured why not. I now know why not.

I dropped two 3 pound ingots into my Lee 20 pound pot yesterday afternoon so that I could cast up some .429's for my Marlin. The total volume in the pot was probably right around 10 pounds as I'm low on tin and didn't want to over due it. As the stuff melted I didn't notice anything out of the ordinary but on the other hand I didn't stand there and stare into a half empty pot either. I noticed something amiss when I dropped my wax and a stick match in and began to stir. The dross was way off from what I'm used to seeing but even then the little light bulb had not illuminated over my head yet. After adding my tin and fluxing again is when the wild purple color got my attention. I should note that I did notice the oatmeal appearance before things had gotten heated up all the way but just dismissed it as the pot isn't hot enough yet.

Having never encountered zinc in my melt before the thought that it had happened this time just wasn't sinking in. Even after casting a few dozen boolits and not getting my perfect little projectiles I was still chasing other issues like the flow wasn't set heavy enough or the mold wasn't up to temp (not likely as it's a Lee). As it turns out, the flow issue was probably related to the zinc oatmeal leaving a turd in the spout and slowing things way down. I blamed it on a low pot but after I roto rootered it with a paperclip I got a real good flow out of it.

Anyway....

The 70-100 boolits I cast yesterday afternoon are "okay", not perfect but usable. I'm guessing that the contamination is minor and hopefully only one ingot was bad. I'm going to dump the pot and probably take my 10 pounder and melt each of the remaining ingots separately and recast them while looking for signs of trouble.

Of course the moral to this story is: Don't buy lead off of eBay!!!!

[mtnman31]

Just melt it in with a larger amount of lead. As long as the zinc content is low, mixing it in with a larger amount of clean smelt will dilute it enough to make it usable. Others will probably say just trash it, which I would say is equally good advice if you don't mind wasting a little lead.

I've only encountered the zinc problem once before. I had a few lbs of smelted lead that was tainted with zinc. I poured it into ingots, around 4-5 ingots that weighed 2lbs each. As I smelted a larger quantity of clip on wheel weights I mixed the tainted ingots back into the smelt. I would guess that each of the tainted, two pound ingots were mixed in with around 40-50 lbs of clean smelt. That diluted the zinc enough to make it perfectly usable with no problems at all. Keep in mind that this mixture is for general plinking and shooting. I don't use it for anything that I expect to develop into loads for precision work. I don't even check the hardness of the plinking mix. Anyway, the lesson learned from that experience is that I check all my wheel weights with side-cutters before I smelt. It leaves no doubt as to whether or not I culled all the steel and zinc out before I smelt.

[tomme boy]

Sounds like pure lead to me.

[Foto Joe]

Definitely NOT pure lead. The boolits are usable, it just irritates me that they aren't the usual quality that I get. I'm out in the garage putting some of 'em in brass right now so the son-in-law, grandson and I can go shoot this morning.

[Bzcraig]

The color purple is indicative of lead not zinc as tomme boy mentioned. If you got good boolits that weigh what they would normally weigh, I doubt you got zinc.

[Tatume]

Sounds like pure lead to me too. It's because of the blue/purple oxidation that I use a bottom pour pot for casting projectiles for my muzzleloading rifles, as I can cover the surface with sawdust and keep my lead from oxidizing. Wait a week and then pinch a bullet with pliers. If it's soft like lead, (and quacks like lead), it probably is lead.

[243winxb]

the oatmeal appearance may also be antimony or copper. My guess is copper as it likes to plug the bottom pour pots. Maximum heat is the fix for all of above. IMO.

[DLCTEX]

I got purple that looked like the chrome exhaust on a Harley when I tried casting with known zinc contaminated ww lead. Wheel weight metal can absorb about 2% zinc and will cast fine boolits. The Oatmeal slush contains most of the zinc and can be dipped off. Cooling and reheating will let more of it rise to the top. The remaining alloy will cast usable boolits, but may need to be cast with higher than normal heat to work well. IMHE Keep a propane lighter handy to heat the spout on a bottom pour in case the nozzle clogs.

[Walter Laich]

Agree with the thoughts above, skim off what you can and keep going. The targets will never know the bullets were a bit wrinkled when you hit them:-)

[dondiego]

Do the ingots clink or thud when dropped on concrete? Thud is soft lead. Clink is a harder alloy and possibly zinc.

[tomme boy]

I also got something similar when I melted down some lino type. It still had ink on them. How hard are they? If you let the lead sit in the pot heating a long time you can get all kinds of color as well.

[Foto Joe]

Interesting posts above, I hadn't thought about copper. In the end I don't think this is going to be an insurmountable problem really. I think that a lot of my problem was the fact that the spout got partially plugged cutting the flow rate down substantially. The ingots themselves don't have that shiny pure lead appearance to them is the main reason I made the statement "Definitely NOT pure lead." After giving this some thought I'm thinking that line of thinking might have been flawed. I'm guessing that whoever cast these ingots might have just cast SOWW with COWW into the ingot mold. Since I've never done that myself I don't have any experience with what the melt looks like.

I've got a couple of pounds of tin wire coming from Roto Metals in the next day or so and I'll fill the pot this next time so I can get my flow correct for a full pot and give it another try. Like I said in the OP the boolits that I did cast weren't a disaster, they just didn't look as perfect as I've gotten used to.

[Tatume]

Soft lead casts better when the alloy and mold are very hot. It wrinkles easily when either one is cool.

[texassako]

I had a similar issue with some mystery ingots, purple and chunky. It was suggested I put a match to the flux and stir, stir, stir to reduce the oxides. Heat and a lack of oxygen were needed. Sure enough, most of it went back into the melt. It probably was not fluxed well during the initial melt by the seller.

[tomme boy]

Every time I pour my ingots they are always frosty when the mold is hot. The first time I pour them in a run they will be shiney, after that they are frosty. So you can not go off of how they look. The more pure the lead, though the shinier they will be. And it also takes a lot more heat to make it work right. The frozen spout doesn't mean it is contaminated. For me, it means I have to turn up the heat a little. Plus if you are using a Lee pot like me, the pot has a mind of its own for the heat. That was why someone came up with the PID to control the temp.

[Whiterabbit]

When I started casting, I would always wonder if this-or-that was zinc contamination.

Then I actually got zinc contamination once. There is absolutely no question about it. When you really get it, you will know. The word "oatmeal" is truly sufficient.

Anyways, it's easy enough to deal with. Toss lots of sawdust, stir, and (I use a mesh screen personally) skim the top, it all floats. You'll pull out alloy content potentially, but you'll definitely pull out all the zinc with the charred woodbits.

No harm, no foul.

[jonk]

I ran into this not long ago. Whatever it was contaminating, it made the lead ungodly hard, was purplish and oxidized quickly, had poor fill out, and left chunky gray slush no matter how much I fluxed. I still think it was zinc.

Dilluting with more lead and ladle pouring got the job done, fortunately it was a small batch.

Now I toss a zinc penny in with each batch; if it melts, I went too hot.