Casting pure lead questions

[bchannell]

I've not cast a lot of pure lead, at least not for a lot of years, but now I'm back to casting round balls and have some questions. I got some lead pipe, and other reasonably pure lead, and cleaned it up and cast ingots. I also built a PID controller to help with temp control.
When I cast round balls, I've been using 750F, and my melt get really blue on top, and seems to produce a lot of crud. If I flux it, and skim all the crud off, it turns blue immediately, and the crud formation starts again asap. Is this normal, what can I do? I've been fluxing with candle wax.

Is it true that the higher temps cause the dross formation quicker?

[Muddy Creek Sam]

Try turning it down to about 725F and see if it helps any.

Sam :D

[lwknight]

Pure lead will always oxidize up quickly. Cover top with a thin layer of kitty litter.

[dicko]

[QUOTE=
Is it true that the higher temps cause the dross formation quicker?[/QUOTE]

Yes. Bear in mind that dirt and dross are two different things, but have to be removed in the same way. Dirt is what's on the lead before you melt it. There'll be lots of it on scrap. Dross is the result of oxidation. Mostly from any tin in the scrap. If there isn't much tin you won't get much dross, but you'll always get some.

The amount of dross will depend on how much tin is in the alloy, and temperature. I cast at 600F, and get so little dross that I can cast all day for a week before needing to flux and clean. At 900F, all the tin from an alloy containing 2% tin, will dross off in 30 minutes. That is serious if you are casting BP projectiles that need some tin.

Of course, you can't cast pure lead at 600. Nor should you be getting excessive drossing at 750. Try 700, and if that works, try 675, but I think 675 might be too close to melt temp to flow freely.

Candle wax works perfectly well as a flux, its what I use. There has been much discussion on this forum about sawdust. It works very well, but it is a matter of availability. Cheap candles are available everywhere.

Don't assume that lead pipe is pure lead. Some was made from pure lead, but a lot was made with 6% antimony. You can't tell by marking it with a thumb nail or other tool, because lead alloy work softens. Extrusion work softens it completely, and it is impossible to tell the difference between the two types. A few years ago I melted a batch of pipe. The resulting bullets were a lot harder than the pipe, and their weight indicated around 6% antimony.

That is equally true of roof sheet. Most is pure but some is 6%.

Don't worry about the blue colour on the melt, it is just oxidation on the surface. For the rest, all I can suggest is clean the alloy thoroughly, and cast as cool as good fillout will allow.

[DIRT Farmer]

I cast round balls for target work, the best way I have found to clean it is to let it "simmer" in the smelting pot for a while. The dirtier it is the longer it needs to set. Lead that keeps releasing crud will vary in ball weight. Just let it cook and flux it several times. Sawdusr, chain saw chips or what ever and float it all out. It pays off on paper.

[Dale53]

I live near Friendship, IN where the National Muzzle Loading Championships are held. I have competed there many times. Over the years, I have talked to a number of "old timers" (some of the people had never gone with smokeless powder and cartridge guns but used muzzle loaders for hunting and target work around the turn of the century (the 20th Century).

Many of them talked about "tempering" their lead. These were the round ball bench rifle guys and boy, could they make a muzzle loader talk. Some of them were a bit jealous about giving out information. However, over the years, they began to talk to me quite freely.

What they meant by "tempering" their lead, they carefully added some tin for better casting. They were VERY careful to make it consistent and it was often stated to me that no more than 1% made a big difference in casting but had little effect on lightening the ball or hardening it. Muzzle loaders do not work well with hard lead balls.

Naturally, I tried it and found that as little as ½ of one percent (.5%) made a definite difference. I finally settled on 1%. It minimizes air holes and wrinkles and it is MUCH easier to have the balls weigh consistently.

YMMV
Dale53