Newbie looking for casting recipe help

[Jaybird62]

After enjoying this site so much for the past few weeks, I finally decided to join. I've been casting boolits infrequently for the past six years, but I only know enough to be dangerous to myself. I've got a RCBS 22-pound pot and a half dozen RCBS molds. Thankfully, the more experienced on this site have taught me a lot.

I've had a 4" x 4" by 3' bar of something in my back yard for three years and I'm just getting around to trying to convert it into something useful. It was an elevator counter weight in the Washington Monument. When I lived near D.C. between 2001 and '05, a co-worker told me his dad had worked construction on the Monmuent re-work and had come up with a bar of lead. I traded him a box of shotgun shells for what appears to be about 230 pounds of what the construction company considered a bio-hazard. I knocked a small chunk off and weighed it on my balance scale and used the process described to determine its specific gravity. It came up 11.27, which to my understanding is probably pure Pb.

My question is: What kind of ratio do I need to mix with linotype to get this up to about 18bh when it's water quenched?

[jdgabbard]

About 4 to 1, or you could go as high as 5 to 1 with adding a little tin. That should bring you up to about WW alloy, which water quenched will harden to about 18-22 bhn.

The reason I know this, is I just asked this question yesterday. ;)

[Jaybird62]

Good info, JD. If I go 5:1, then how much tin? I've got 2 lbs. of 50/50 solder, and 20 lbs. of lino, so I'm trying to figure out how much more of each I'll need to scrounge. I can get lino for $2 per pound, so I might go with the 4:1 ratio. The 50/50 solder is pretty pricey.

[jdgabbard]

Jaybird, I'm sorry. I did some math just now, and came up with some other figures. You'd want to go 3:1 or 4:1. WW alloy is 95.5 - .5 (tin) - 4 (Antimony). Lino is 84 - 4 (tin) - 12 (antimony).

To get something close to WW alloy you'd want to go with 3 parts Pure Lead to 1 Part Lino. Which will yield something close to 96 - 1 (tin) - 3 (antimony). When I use WW alloy I usually go ahead and add .5% tin, so this is identical to what I use. It will just be about 1% shy on the antimony. Which is going to yield a bhn of about 16-21 when water dropped, probably. And it should cast beautiful boolits.

To stretch your lino alloy you could go 4:1. Which will give you 96.8 - 0.8(tin) - 2.4 (antimony). This will probably water drop to a hardness of 14-16, and without water dropping will drop to about 8-10. But if you add enough tin to bring it up to 3% you will have an alloy called Electrotype. It doesn't harden a lot when cast, however it does yield about a 12 bhn when not heat treated. With water dropping it will probably drop at about 14-18 and will normilize probably somewhere around a 16 bhn.

Now this is just going off of speculation. As I am thinking about doing this myself. WWs are few and far between for me right now. I am have more or less been pressed to go ahead and order alloy off the net. Untill you start alloying whatever you have, and test it, you'll never really know what you have. But this should give you a fairly accurate idea as to what you can expect.