Lead and "Not Lead" ingots?

I've only been casting for about 2 years or so. When I first started out I bought 100lbs of melted COWW that had been melted down for race car lead. They used a valve cover as a mold and filled it up with melted Wheel Weights or so I was told. I chopped up those 50 pound ingots and melted them down into smaller ingots. This past weekend I was alloying some pure lead with pewter and found some of these older ingots and I dropped a couple of them into my large cast iron pot that holds about 30 pounds of lead or more.

Once the lead had melted I was stirring the pot and my ladle kept hitting these chunks in the bottom of the pot. I didn't have my thermometer with me but the lead was "barely liquid", still just a little slushy but stirrable. I fished out a couple of the chunks and left them in the pot a few more minutes but they didn't seem to be melting. So that freaked me out a little. I fished 3 of them out and sat them aside. In the photo are the nice shiny new ingots of this weekends alloying and that gray turd next to it on the right is one that I fished out. Is that just lead with a lot of zinc mixed in? I had been worried last year that my original batch of race car "wheel weights" might have a substantial amount of zinc mixed in but lawd-a-mercy I didn't know anything then. Not sure I know much more now but the gray turd on the right doesn't look like the shiny lead ingots I have bought or cast since then. What do you think is in that gray ingot on the right? Obviously I was able to melt it a couple of years ago but the temp was probably pretty high

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Does it thud, or ring when you bounce it on concrete?

The dark gray one is more of a thud. The one I know is the lead alloyed with pewter has a brighter ring to it

Drill a small hole in it.. drop some Muriatic acid in there. it will fizz like crazy on those lead covered Zin-Kins .. uncle mike

Ok, but where do I get a little Muriatic acid? Not like I need a gallon of the stuff around the house

You can get a quart (still way more than you'll ever use this way, I know) any place that sells pool supplies. Handle with care: very corrosive. My old quart started eating through its plastic container after a couple or three years.

IIRC, zinc floats on molten lead. Was there anything on top of that blob that might have kept it from floating? If it was a chunk of zinc WW that was encased in lead, could it be that enough unmelted lead stayed around the lighter stuff to weigh it down? In the second case, putting some muriatic acid on the lump might not cause any fizzing if the acid can't get in contact with any zinc. Like uncle mike said, you might have to cut or file the exterior to get at what's underneath.

Thanks Kevin. The good lead is what you sold me a few weeks ago and I had 3 of these dark gray muffins sitting on the bottom of my big pot. The pot of lead had just reached the complete liquid state but was still thick and I was stirring these around the bottom of the pot. I fished them out a few times and let them back in until I realized they really weren't melting but just a little. I compared these 3 dark muffins to maybe a dozen or more from that first batch of race car lead and they were definitely darker than the shinier lead. Next time I go to H.D. I'll check their pool supplies, but that will be a while given the current conditions. in any event, I figure at least I didn't contaminate this batch of sweet lead I got from you.

Lead from race car counter weights can be about anything. Pretty often wheel weights were used just because of the close association between race cars and tires and wheels. Most non casters don't know much about zinc and theres no real reason for them to sort weights for a counter weight. Anyway it sounds like you got some zinc in your mix. But all is not lost! If it turns out to be zinc contaminated it might still cast ok. If not, it can be diluted until it does. And you might have caught all or most of it.

Kevin, thanks for posting about the acid. I have a gallon thats going on 3 years old. I need to set it in another bucket. I don't need that kind of mess in the shop!

I seriously doubt if the acid is destroying the plastic container. More likely, it has been exposed to sunlight which causes plastic to get brittle and crack easily from the UV rays.

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Originally Posted by dondiego

I seriously doubt if the acid is destroying the plastic container. More likely, it has been exposed to sunlight which causes plastic to get brittle and crack easily from the UV rays.

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I agree with this statement. I’ve stored wheelweights, lead, and Linotype in old 5 gallon buckets, that had been outside exposed to the sun, in my garage. Been there for many years. When I went to pick one up the bottom or sides would crack with everything falling out. Sort of like biodegrading. Leave a 5 gallon plastic bucket outside and it will gradually fall apart from UV.

I have had the same experience with 5 gallon buckets but my acid has not been exposed to the sunlight. At least not on my watch. It won't be any big deal for me to just set the gallon jug of acid in a 2 gallon plastic bucket. I'm not going to pour it, just try to arrange to contain any leaks. But thanks for the comments.

Just my personal experience, but I will state with certainty that the quart of pool acid that was blistering never saw the light of day after I bought it. The container sat in another plastic bucket in my basement for zinc testing, but since I soon switched to isotope lead, that didn't happen for years until I accumulated a pile of pewter (read here of zinc parts in combination with pewter). That's when I noticed the small blisters on the muriatic acid container.

I've seen what happens to sun exposed plastic containers: my wife has shards of them all over her back yard vegetable garden. Like you said: cracked and brittle to the point of crumbling in the hand. What I'm talking about is small bubbles forming on the bare, unpainted and uncoated white plastic of the acid jug.

I suppose there could have been unnoticed spillage when I used the acid, that attacked some unappreciated clear coat on the exterior of the jug. But to my eyes the blisters looked deep, like they could have started from the inside. Even if the outside bucket caught any leakage, I've seen what HCl fumes can do to metal, so to be sure as possible I went ahead and transferred the acid into glass (which is inside another plastic bucket).

Any update to this? I have an ingot that I did not make that did exactly what the OP says his did. I fished it out and threw it on the floor to cool. It definitely thudded and did not ring. My pot was set to 650 degrees or so. The other ingot I put in with that one melted quite quickly.

Another thread mentioned it could have been battery lead. Does the impurities in battery lead make it melt at a higher temp?

I have a batch (pan) of wheel weight lead that had a lee ingot of pure in it when I got it. The wheel weight lead will get liquid and can cast well while the pure ingot never melts. If you kept the heat low, and had a portion that was pure lead it would not melt and remain solid. That would only be the case if the lead was not homogeneous to start with.

If your gray ingot thuds it could be pure lead and the pot/alloy didnt get hot enough to melt.

Since it was on the bottom, it wa more dense than your alloy. Zinc wouldve floated. Pure would be st the bottom.

Do a hardness test and let us know what the BHN is?

That's a pretty straightforward and reasonable explanation! The OP did say the melt had barely gone liquid. Most of the lead alloys we use melt at significantly lower temperatures than pure, and are definitely less dense, so a puck of pure will sit on the bottom until the melt reaches 621F for long enough to heat the pure ingot to that temp.

The cupcake on the left doesn't look very good either!

Those acne scars on the puck on the left look like what happens from off gassing from coated non stick bakeware. It stops when the coating burns off, and doesn't do anything to the alloy except make the ingot ugly.

If you were melting an alloy with Tin in it, the melting point would be lower than pure or near pure lead. Could be your gray clumps are just close to pure and your temp was not high enough to melt them. Just a thought.

Also, could be something else, including Zinc!

I once melted some lead weights that I got from a racer. When it went to liquid a bunch of lug nuts floated out of the mix along with a few spark plugs. They put anything heavy in the pot!

I haven't had a chance to get the acid for the acid test. I still have the cupcake in the garage and it does thud when dropped not quite the ring the ones of known alloy have. There are just a couple that look like that. When Kevin C mentioned "coated non stick bakeware" Bingo we have a winner. That was my first batch and my first cupcake pan and I didn't know about the non-stick coating being an issue. I've about burned that pan clean now.

Planning on melting down and alloying 50lbs I got from Defcon-One today if my hotplate will get hot enough. Its 1100 watts and I read around here somewhere that it might work even if slowly.
If I can get the 50#s alloyed, I'll try and melt that ugly cake on its own and pay attention to the temp today now that I have my thermometer handy.

Happy Easter to all.

No luck on mixing the alloy today. My little hot plate wouldn't get hot enough, it melted the pewter and just a little of the lead. Going to have to find a used Coleman stove or turkey fryer burner. Oh well, I did sit down and cast about 200 .45 SWC for when I get my next batch of PC powder from Smoke.