Mysterious Exploding Lead Pot

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  • Last Post 09 February 2020
John Alexander posted this 01 February 2020

My lead pot exploded 15 minutes ago. What a mess.

This won't be a very useful safety warning though, unless I can figure out the cause.

I was spooning sprues ( some probably still warm) into the unplugged but still molten pot as I dipped them out of a metal coffee can with a tablespoon.  As far as I know exactly as I have hundreds of times before, including once at about the same time yesterday. When boom and about half an inch off the top of the full pot flew in all directions.  The only causalities were a flannel shirt, one lens of my glasses, and my pride.

I have a messy clean up of a variety of tools, the floor and eight feet up the window behind the pot. Don't know how the flying lead avoided hitting my face, the only bare skin available. My beard and old man busy eyebrows caught some of it but no burns.

There is never any water in the shop and wasn't any today except in me but I didn't have a runny nose and wasn't leaning over the pot.

The last bit of lead in the coffee can yesterday was dumped directly into the pot so it was empty today.  However, I did scrape up some of the bits and pieces of lead on the floor and dumped it in the coffee can today and my best theory so far is that a lost primer was scraped up with the lead near the pot. I don't drop many primers and am pretty anal about hunting them down. Also where I prime is about 8 feet from the lead pot but they are round and can roll. I suppose a spider, or other life form could have been in the coffee can. Any theory is better than none.

I would appreciate your thoughts on what might have happened so I can avoid a repeat.  Once is enough.

John

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RicinYakima posted this 01 February 2020

Weather? We had 50's temperatures and high humidity coming up from the coast today; condensation?

Primer? If you are like me, not likely as I hunt them down so the bulldog doesn't' bite them.

Lifeform? Went to the range today and it was so warm the field mice were out. So there could have been the black widows coming out also.

Gremlins!

 

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Duane Mellenbruch posted this 01 February 2020

If the floor is wood, not too likely to pick up moisture.  If concrete, there might have been some condensation from the concrete.  And you might have tracked something on your shoes into that area as well. 

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Ross Smith posted this 01 February 2020

It's most likely moisture from condensation off the floor. It takes very very little. If it's cold and you pour hot lead into your ingot mold chances are you've seen it bubble a few times. that's steam coming OUT of the cast iron. Water turns to steam at a ratio of 1:144 if I remember my long ago fire training. That's explosive. One drop would have emptied your pot. It's happened to me.

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stevebarrett posted this 01 February 2020

 

I had a similar experience, though not half so dramatic, not long ago. I had a pot of lead alloy I wanted to stir, and picked up my cheap wooden-handled stirring spoon off the shelf and poked it into the pot . A minor explosion as stuff spat out which I completely couldn't understand at all. There was no evidence of water anywhere around. My eventual suspicion was likewise, namely that an insect or something had been sitting in the spoon and I hadn't checked when I dunked into the mix.

 

Steve 

 

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BigMan54 posted this 01 February 2020

This is why I load in the Garage, and cast on the Patio.

 

Long time Caster/Reloader, Getting back into it after almost 10yrs. Life Member NRA 40+yrs, Life S.A.S.S. #375. Does this mean a description of me as a fumble-fingered knuckle-draggin' baboon. I also drool in my sleep. I firmly believe that true happiness is a warm gun. Did I mention how much I HATE auto-correct on this blasted tablet.

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99 Strajght posted this 01 February 2020

I have had this with a cold metal spoon or cold lead that I was adding. Not always but I do not do that any more.

Glenn

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Larry Gibson posted this 01 February 2020

"However, I did scrape up some of the bits and pieces of lead on the floor and dumped it in the coffee can today and my best theory so far is that a lost primer was scraped up with the lead near the pot."

Bet that is it exactly.  Did that a couple times in the past and learned to not put sweep ups in to molten alloy.  I'll pick out the larger pieces of sprue and put those in but not the "sweepings".

LMG

Concealment is not cover.........

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Lee Wiggins posted this 01 February 2020

   In the future you could avoid this happening again by cutting the spew with a heavy leather gloved hand. Drop the spew back in the pot as you go. No spews to add later and I have found that the spew cut on the bullet base is much smoother than whacking the spew cutter with  a  broom handle.

   If you find a primer cup with no firing pin dent in the dross you can be pretty sure what happened . Glad you escaped unharmed. 

                                                   Lee Wiggins

 

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4060may posted this 01 February 2020

I usually cull the bullets at Sizing/lube, throwing the culls in a steel bread pan my BIL gets for cheap at garage sales...

one time I didn't check the pan and dumped the culls to fill the pot, BOOM lead and tinsel fairies everywhere, had a heavy jacket, gloves and glasses on, only thing that freaked me out was the lead on top of my head, no burnt flesh but lost some of the hair I do not really have.....seems there was two primers in the pan, one went into the pot...I look twice now on everything i put into the pot

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Mouldknocker posted this 01 February 2020

It is most likely caused from temperature differences. Never put/stick anything cold into, or onto molten lead. I preheat everything, always.

Pour molten lead into cold ingot moulds and you can get the same result.

The Tinsel Fairy is very sneaky indeed!!

Jeff

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Bud Hyett posted this 01 February 2020

Concurrence with everyone talking of primers in the mix, I've had that happen to me. The good thing was this occurred at the beginning of casting as the pot began initial warmup. Working to get ready as the pot warmed and suddenly there was a very loud boom and the sprues in the pot on top scattered. 

A spent primer may have enough priming compound left to explode again.  Not nearly the force of a new primer, but enough residual to cause a problem. 

I use cornmeal as a flux, it boils and bubbles when stirring it in. I've learned to set some cornmeal on the hot plate to dry and drive the moisture out as I begin the casting day. Then I have less boiling and bubbling as I flux. The boiling and bubbling comes from the corn oil within the ground corn.

Farm boy from Western Illinois, living in the Magical Pacific Northwest

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Ken Campbell Iowa posted this 01 February 2020

...cornmeal ... which reminds me ... you can get a 50 pound bag of bulk ground corn at your farmer's supply for under $10 ...  a lifetime supply even if you feed half of it to our bird friends ...

ken

 

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Brodie posted this 02 February 2020

John,  Probably caused by moisture of condensation.

B.E.Brickey

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sghart3578 posted this 02 February 2020

Gotta be a primer.

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David Reiss CBA Membership Director posted this 02 February 2020

John,

Don't know whether it was a primer or moisture, but I have to side with moisture. I have a separate are where I cast so primers never come into play. I also cast indoors, so the introduction of moisture is very unlikely. I add my sprues back to the pot when I take a break or when the pot gets low and I am needing to add more lead anyway. However many times I've had the molten lead bubble up, but not explode. If as Ross states, the bubbling is from moisture, then I am at a loss as to how it could be. Most of the time the sprues are still warm from being pilled together. So some of the incidents have a cause, but I'll be dammed if I know what is is.  

David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
-Services: Wars Fought, Uprisings Quelled, Bars Emptied, Revolutions Started, Tigers Tamed, Assassinations Plotted, Women Seduced, Governments Run, Gun Appraisals, Lost Treasure Found.
- Also deal in: Land, Banjos, Nails, Firearms, Manure, Fly Swatters, Used Cars, Whisky, Racing Forms, Rare Antiquities, Lead, Used Keyboard Keys, Good Dogs, Pith Helmets & Zulu Headdresses. .

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John Alexander posted this 02 February 2020

I want to thank all who have suggested ways to avoid having another lead pot explosion. I think those suggesting various mechanisms that might have resulted in moisture getting into the pot would be strong theories if I still lived in Maine with it's sometimes high humidity.  I think it is less likely here in the desert.  The relative humidity was 30% that day.  Our furnace is in my enclosed shop area and the heat from the furnace keeps the shop temperature well above the outside temperature all winter long making it difficult to envision condensation from the outside air that gets in. None of my tools or molds rust anymore.

I think I found an additional clue as I was cleaning up the mess yesterday. After scraping lead off the area affected I swept things into one  area. After picking up what I could by hand I spread out the fine stuff and examined it under good light. I didn't find a live primer but I did find one shiny gas check and one spent primer both originating from the same area a dropped live primer would have come from showing that an unrecovered live primer could have made the same trip.

Whatever caused the explosion I will never again dump sweeping into a hot pot.  In spite of being a depression baby with a fear of letting a penny get away, any lead too small to pick up will go into the dross can and I will become even more obsessive about finding any dropped primers.  I will also avoid putting any porous or cold material into a molten pot.  One lead pot blow up is enough for a lifetime.

 

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TRKakaCatWhisperer posted this 02 February 2020

Moisture doesn't make noise - lots of tinsel but no more that a bloop.  Someone posted years back about a large moth that took a dive into the lead pot resulting in an instantaneous visit from the tinsel fairy...

 

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Brodie posted this 03 February 2020

My friend Rubin used to cast commercially.  One night he emptied a bucket "containing nothing but wheel weights" , that a friend had given him.  That was the last time Rubin ever trusted lead from a "friend".  The bucket not only had live primers in it is also had live 45 acp ammo.  Rubin poured it into the lead reservoir of his master caster machine.  He left the basement shortly thereafter in a big hurry.  He was cleaning lead off of everything in that basement for a week.  I don't know what he did with his "friend", but I'll bet he never ever poured lead into that machine that he hadn't examined first.

B.E.Brickey

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Smoke Ratchet posted this 05 February 2020

What ever it was …...

I'll bet it came off of the floor. Very glad to hear that you were not injured.

Smoke Ratchet

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stevebarrett posted this 05 February 2020

 

I’ve been wondering about the undetected primer as a cause of the explosion, and it’s probably just my ignorance. If I’d been asked whether a primer dropped into molten lead would explode, I’d have had to say I just didn’t know. It’s obviously not something one is in the habit of doing, although I wouldn’t volunteer to try the experiment. Is there any evidence on this?

 

Steve

 

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