Smelting and Lead Mysteries

[Fugowii]

I've only been into this actively for about six months to a year. I've smelted a lot
of various lead in that time and cast thousands of boolits. This is only to set the stage
that I'm not totally clueless about the process. Close to, but not totally clueless. :wink:

This morning was a bright sunny day around here with a reasonable wind so I decided
to melt my stickies. I sort them out of the WW buckets and do them separately. I
figured that with the wind and it being a weekday I wouldn't run into any of the neighbors
looking out the window wondering what the heck the nut job that lives near them is doing.

All goes well and I finish up with around 30-40 pounds of ingots from this batch. Lots
of zinc in those stickies since I don't sort, but I keep the pot right around 650-675 so
all is good.

Now is where the mystery starts. I've read that stickies are close to pure lead, but that
is not my experience. A large previous batch, the first one I melted actually measured
exactly the same as my WW (10 BHN) right out of the pot. I haven't measured this
batch yet. I'm not expecting much of a difference though.

After getting as much of the sticky lead out of the pot as I could I decided to go a
little further with the smelting and melt down some scrap I had been given. This was
flashing lead and some short rods of lead that were not more than 1/3" in diameter
and they were about 12 inches long. Most of what I read about the flashing I expected
to get close to pure lead and the rods seemed sufficiently soft that I expected them
to be of similar hardness. I didn't have a lot so I only got eight one pound ingots and
a residual pool of lead that must have come in around two pounds.

Still with me? Good. I have a Lee 10 pound pot that I use for pure lead casting and
I wanted to drain the pot as it was half full of very pure lead (BHN of less than 5) but
I figured what the hay, I might as well toss the left over pool of lead from the flashing/rods
as I expected this to be close to pure lead also.

My results could not have been more surprising....

First, the flashing/rods/sticky pool measure a 12 BHN :veryconfu
Second, the mix of the left over pool from this mixture when added to the pure lead that
was in the Lee pot produced ingots that measured 9+ BHN. This is to be expected
since adding the harder blend into the softer blend would account for the increase.

So, to further understand something, anything about what I am seeing I did a sample
of melts that go back around six to nine months ago. I have four different ingots from
various melts.

1) This was a stick on melt that measured 10 when sampled a few days after the
melt. It now measures 12+
2) This was a more recent melt (two months ago) and it to measured 10 after the
melt. It also now measures 12+. This was lead from a RFI room teardown.
3) This is the most recent melt before today. A month ago and it was range scrap
mostly from an indoor trap. It measured 8 a month ago and now meausres 9.5.
4) This is the oldest melt and the alloy is unknown but was from an older caster
that got out of casting. It measured around 10 when melted and now comes in at 13.5.

Why am I going through all this? Well, to understand what level of hardness I will see
when I cast boolits with this material. I've water dropped boolits and they have made
no difference wrt the accumulation of leading in various firearms I shoot. I've shot
darn near pure lead Hornady boolits and they produced no leading at all in a couple
of firearms so I've given up the water dropping at least for the time being.

Can I assume that when I cast boolits from these ingots that the hardness level will
drop to the softer levels and then re-harden over time? I'm scratching my head over
what the heck all this information means and the results I expected didn't happen.

Thanks for listening. Any observations/comments are appreciated since I'm not really
sure what the questions are! :veryconfu

[sagacious]

Can I assume that when I cast boolits from these ingots that the hardness level will drop to the softer levels and then re-harden over time?
Yes, generally. The caveat is that the rate of air-cooling in your cast bullets will be much quicker than the ingots, and thus you may measure greater hardness in the bullets. Always measure the actual as-cast bullets if you want an accurate hardness.

Lead sheeting/sheathing is not always pure lead. Often it contains a few percent antimony.

Stick on ww's are not always pure lead. Some are much harder. I like the harder stick-ons and wish I could get more of them.

Good luck.

[sqlbullet]

The hardening over time is the result of a grain refiner in the alloy, usually trace amounts of arsenic. And yes, this will occur each time you melt and re-cast.

The end result of your experience is the same as mine, and apparently that of Sagacious as well. The conventional wisdom is a starting point for the guessing game of what you have, not an end point. I have come to expect that I have 'stuff' and until I test it, I treat it like stuff.

The one exception is any lead that I get from the radio-pharmacy that was used to shield radioactive medicine. When the FDA approves the medicine, part of that approval is the container and the labeling. A change in the alloy of the container requires a new approval, since it could theoretically impact the efficacy of the medicine. Given the expense of the approval process, this rarely occurs. Therefore, I catalog the containers and the alloy they are made from and rely on that information over time. So far it has been consistent.

[montana_charlie]

I think that when the stick-ons first hit the streets they were pure lead, and remained that way for quite a while. But, since clip-ons have become so variable, it stands to reason that stick-ons will follow that trend...until all lead wheel weights are totally banned.

When that happens, I am worried that the normally dependable x-ray shielding will become as unpredictable as current wheel weights...because the scrap currently being used for the weights will become the metal of choice for shielding.

CM

[sqlbullet]

You aren't wrong Charlie.

About a year ago my source collected a bunch of very old isotope containers from depot's in remote areas. Some of these were 10+ years old. They were all pure. It appears that at some point the medical radiation community switched from pure lead shields to the 96/3/1 I see almost everything come in today. The only exception are some of the iodine shields which persist as pure lead.