How much zinc is acceptable?

[Duckiller]

Cooking lead this afternoon. First batch was half way heated when I saw a large zinc clip-on weight sitting on top of everything. This is a bucket of weights that I have sorted through at least twice. Got the offending weight out of the pot, but everything else was too hot to sort any more. In this day and age I am sure I am getting some zinc in my alloy. How much can my alloy tolerate and still cast decent boolits. The other alternative will be to treat each batch that I cook with sulfur. something I don't think my neighbors would enjoy. Has anyone knowingly left a weight or two of zinc in a melt? I generally melt about 30 lbs of lead at a time.

[Cherokee]

I have cast good bullets that did have some zink in the alloy, I just don't know how much. Try a few casting from your melt pot (not your casting pot) and see how they do.

[Charlie Sometimes]

I use zinc'd alloy, occassionally.
Sometimes, I have to run the pot a little hotter, but I get good boolits, so I don't mind.
I have to skim the melt more often too when zinc is present, and since I cast with a ladle, the ladle gets dirty a little faster too.
I know you can't make shot from WW that have zinc in them, so it depends on your application, too.

I don't know how much is/can be removed by sulfur treatment, or even how much remains after continual skimming at lower temps, but thinning it is about the only way to "neutralize" it.

[Casting Timmy]

I'd agree with giving it a go....I'm sure we,ve all got some zinc in our alloy at times.

[Hastings]

Goodness, I find it even hard to melt pure lead stick-on's when doing my wheel weights. Normally they come off when I scoop the zinc, iron, and clips, but I sort them out for adding later to the same pot when I get it hotter. The purer lead is sometimes partially melted when I scoop it out.

And no, I've never used a thermometer. And zinc is not a good thing to have in your alloy. I've seen it before many years ago. Even a tiny bit will interfere with your boolit making by modifying the filling characteristics of your lead.

[Defcon-One]

I sort my wheel weights once and catch over 95% by sight and sound. Then I melt them slowly with a thermometer in 50 lb. batches. I never let it get over 700 degree F. If it goes close then I quickly toss in a few more (known dry) wheel weights to pull it back down fast. It works well, I get very few Zinc weights, but when I do get one, it floats and absolutely will not melt at that temperature. So, I skim it off and into a separate pan. Great lead and almost no risk of Zinc contamination.

Buy a good thermometer and melt smart. It only costs about $25-$50 and if it saves one batch of lead, it has already paid for itself. Don't tolerate Zinc, just prevent it.

A note to Hastings: I sort out my stick-on wheel weights and melt them separately and pour them into ingots. They are close to pure lead and they are great for thinning down an alloy. Also, they will thin down and soften your clip-on WWs if you melt them back in. You'll never know exactly what you have in the pot with a watered down mix of clip-on and stick-ons. Just a tip to consider.

[Duckiller]

I don't want zinc in the melt but I found several zinc clip on weights in the batches I processed yesterday and today. I am not sure if I should be happy because I got all the zinc or sad because even with three sorts I didn't get them all. I don't run my fryer too hot but I have no idea how hot the melt is at the bottom of the pot where it is liquid. I can't get a rigid thermometer through the pile of weights and an optical thermometer registers the temp of the top weights that are too cool to melt. Just empty clips floating on top of the melt. Hopefully I got all/most of the zinc and i am over thinking and worrying too much.
Stick on ingots should be kept separate from clip on ingots so you know how you are modifying you alloy. Also if you get into muzzle loading the stick on ingots are suitable making projectiles that go in the out end of a barrel.

[Defcon-One]

I'm guessing that you probably found them all! If none of the ones that you recovered were melted in any way, that is a really good sign. If your lead was not clumpy, that is a good sign too.

I use a thermometer and put it down through the wheel weights to touch the bottom before I start the stove. It gives me a pretty good read and lets me know when things are gonna start melting so I can slow down a little. As I said, I miss a few too, nobody is perfect. Just do the best you can and have fun!

[a.squibload]

Thermometer:
http://castboolits.gunloads.com/showthread.php?t=102777