What happened and how do I fix it?

[bhuch5]

Long time lurker first post. Was casting last weekend and when I finished up I shut off gas stove and let my lead pot cool. I was somewhat upset when I saw my cold lead the next morning. I have never had this happen before and it did not look right. Lead appears to have collapsed in the center of the pot leaving a 3" wide crater nearly an inch deep. Lead appears very grainy (like coarse sand) and crystalline in texture.
My question is twofold: what did I do and can I fix it ?Lead was a mix of wheel weight ingots and some of what I thought to be pewter about 35# total. Shot some bullets from this casting and they leaded badly in my .40cal. My first thought was TOO much antimony but I need a more better opinion. Thanks for your help. Bruce H
http://castboolits.gunloads.com/imagehosting/thum_197204e1bd9063e196.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=1448)http://castboolits.gunloads.com/imagehosting/thum_197204e1bd9067aa45.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=1449)http://castboolits.gunloads.com/imagehosting/thum_197204e1bd906b3086.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=1450)

[bumpo628]

Best to start by getting some pool acid (muriatic) to test for zinc.

[Echo]

My non-guru response is that the melt started solidifying at the sides, from the heat being radiated away, and the melt started shrinking, leaving a pit in the middle. Can't comment on the leading...

[aussie460mag]

I have a had a similar thing in my lee 10lb pot when i filled it then left it to cool, This happened when adding solder to my mix ... maybe to much tin?

Hope you find your answer.

[Bomberman]

I have a had a similar thing in my lee 10lb pot when i filled it then left it to cool, This happened when adding solder to my mix ... maybe to much tin?

Hope you find your answer.


That was my first thought too...too much tin. How much of each did you put in?

[docone31]

It is the "pewter". I had that happen also.
The material in the "pewter", was a material that is like white metal, or pot metal. It melts way below lead.
You will need to "sweeten" the melt now. A little of that in lead will act kinda like wheel weight alloy. Before I caught on, I cast a bunch of castings. Miserable stuff. Even with "sweetening", I still had off colour spots on the castings. Needs another mixing.
You will have to get that stuff in ingots, then mix them in another batch. Added to lead, it makes a nice batch.
Good luck.

[Southern Son]

BruceH, I don't know if the leading and what happend in your pot are joined. I melt over a gas flame using an old gas bottle for a pot and I have had teh same thing happen, even when I was using certified pure lead and tin, both bought from a foundry. The mix was 20 pars lead to 1 part tin. There was no leading in my rifle. The hole in the top of mine ain't as round, but it is deep. This only happens when I leave a fair bit of lead in the pot and turn off the gas. If the pot is only half full, then it don't happen.

[Gswain]

I have a theory here, noticed he is in oregon, where it is cooler. When we cast a boolit, we pour a sprue puddle that gets partially sucked into the mold as the alloy cools and shrinks, accounting for maybe 3% of the volume of the bullet. If it was cool-ish on the day he was casting, what may have happened is this : alloy in pot starts to cool on the surface first, forming a skin, while all the alloy below is still warm enough to stay liquid. Notice that appears to be a deep pot. I suspect that when the rest of the alloy began to solidify, it caused a "tear" in the surface skin that had formed, resulting in what we see now as that odd cracked scar in the top of this melt. Its probably just fine.

[BulletFactory]

What he said ^

[BulletFactory]

:hijack:

One of the best parts about not smoking anymore, is that I can smell flowers in bloom when Im driving or when walking down the street.

[Rangefinder]

Your ingots are really frosty--running hot. High antimony will cause a crystalline structure visible, and I noticed in mine that it is more prominent when I run my melt hot. I'm not sure that would be the cause of your leading, however. You said it was for a .40 cal. Handgun, or carbine? Either way, it's likely more a size issue. But for the record, I use a 50/50 mix for handguns---WW and pure. I only add tin in small increments when I'm not getting good fill-out. High antimony+tin is saved specifically for my high-pressure rifle boolits only. It could be that the boolits were alloyed too hard to get a good seal at the base of the boolit causing gas jetting where a softer alloy would expand under pressure enough to seal the base.

[bhuch5]

Felt I needed to clarify a few points in my initial post. First the gun in question is a handgun. I was trying to work up a light load for my daughter. She says the .40cal is too snappy and I refuse to reload for 9mm. Can't pick up cases and bullets.
Next the leading issue-When I first looked down the barrel prior to cleaning it looked to be a leaded mess. After running several patches down the leading was minimal. Fine gray ash nearly filled the grooves. The culprit was powder residue from a can of dirty OLD Hercules Unique .
Third-yes I ran my lead hot. Was having a little trouble with fillout so I added what I thought to be pewter for the tin. Still not sure now of what it really is.
Last- I have not yet been able to test for zinc in my pot, but intend to do so before casting again.
Thanks for all the advice, opinions and replies. Hopefully will get this figured out with this new info. Good shooting-Bruce H

[WHITETAIL]

This is a combo of two things here.
One you were running hot and you
had a high tin content.
Just melt this lead and make some ingots
Then mix it 50/50 with some stick on lead.
Don't freat it is OK.[smilie=w: