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