Lead Pot Explosions?

[Ken Hansgen, 11094]

Somebody on this BB posted a comment that if a lead pot is allowed to cool and harden when full, there is a chance for an explosion when it is re-heated because of the lead underneath melting fist and expanding, thereby causing it to explode thru the still-hard crust. (Sorry, "Somebody", but I looked but could not find your post.) He advised always emptying the pot before cooling, forming lead ingots which then need to be re-melted when beginning a casting session.

1. I have been in this game a long time, but this has never happened to me. Have I just been lucky, or what?

2. Has this happened to you, "Somebody", or did you just hear about it? Where?

3. In either case, what were the exact circumstances of the accident? Was a piece of another metal (with different properties) left in the cooled lead, such as a spoon to remove dross, a ladle, or that part of the mechanism of a Lee Bottom-Pour Pot? Did it happen in an unheated space in the coldest weather the north has to offer? Was it very hard lead, or very soft and pure? Was it an electric pot or one over a gas or other open flame?

I have been made a little leery about this, so much so that I now leave the area when my electric lead pot, full of solid lead, is re-melting.

[ken chrestman]

Ken, I recall a post where a "Newbie" commented he dropped his cast bullets in water when he opened the mold. I warned him that water in molten lead would explode even a drop of sweat, etc and to discontinue his practice of water and molten lead. Don't recall explosions caused by reheating the lead furnace, nor hav I seen it happen either like yourself. Hope this helps;

Ken Chrestman, FEC Tennessee 7147V

[matt]

Ken,
I have been leaving my 2 lead pots full since i started casting. The only time I have had the pots explode is when the pot was fully liquid and i was adding metal to the pot. Usually it was scrap pipe I had gotten at the junk yard that had moisture that was trapped in the cut. The pot would start to bubble fiercely and then I would quickly move away. Cant see how you would end up with moisture trapped in the pot with the pot full it would have either gone away before the pot cooled down or would have erupted.
Matt
Winslow's Battery D 1st NY LT Artillery 9775v

[ms3635v]

I've been casting since before I joined the NSSA in 1979 and have always left the casting pot full. I have never had a problem and get great casts each time I heat up the pot.

[Gary Van Kauwenbergh, 101]

It's happened to me with a 20 lb. electric pot, but not as dramatic as touted. When the top of the lead solidifies, the the material below shrinks as it hardens, you get a void inside the lead, and thats the problem when you reheat it. Some lead did splash outside the pot, but I wouldn't call it an 'explosion'.

I do have lead splatters on the ceiling of my garage though. They came from a session where I was melting down scrap lead pipe, and I missed one piece that had both ends pinched. I was using a large pot that probably holds 80 lbs of lead. I normally step away from the pot to avoid any splashes and fumes, and luckily, I was away from the pot when it happened. Stepping away from the pot while the material is going from solid to liquid makes good sense.

Here's another one: If you use any of the commercial powders to clean your lead, and use that same spoon to stir and skim, you need to watch out if your spoon has any residue from your last session. If you just dunk the cold spoon with the residue into the melted lead it will bubble up and sputter.

[Richard Hill]

The only time in 25 years of casting that I've had this occur is when I’ve dropped cold lead that had moisture on it into a pot containing hot lead. Water expands to something like 1700 times is original volume when it boils, and a lead pot at 900 degrees or so will cause this to happen near-instantaneously. I had expected the water to boil off very quickly and so dropped it in at arm’s length, but what I got was a fairly violent explosion. It’s been several years since I did this and I use the lead splattered on the ceiling of the carport to illustrate this effect when showing new shooters the tricks of bullet casting.

[Timmeu]

I had the only episode with a lead spatter just the other day. I had both my Lee pots going and had just reloaded the left hand pot with new lead ingots from a muffin pan. As I began to cast from the right hand pot the left hand pot shot out a fountain of lead that cleared the pot by 5 or 6 inches. I have used over 100 of these ingots in the past 6 months and never had a reaction like this prior.

I now cover the top of the pot with a piece of lead about 6" across and about 1/8 thick from some roofing or plumbing job. I was surprised to say the least and watch the pots as they begin their remelting.

[Ken Hansgen, 11094]

Marty, Thanks for the input, 'tho it doesn't sound like the accident I described. A good lesson to us all, tho', covering the melting pot after new solid lead is introduced.

[Fred Jr]

Several years ago I left my bottom pour pot full to the top. When I remelted it for some reason the melted lead came out the spout and I couldn't get it stopped as the plunger was stuck. Quite a mess to clean up! Since then I only leave a couple inches in the bottom and have had no more problems. ANY Water dropped into melted lead will cause an explosion, at least it did when a drop of sweat fell on a piece of lead I was putting into the pot! Made sure that never happened again!

[Ken Hansgen, 11094]

Fred, I also used to use a bottom pour pot, but gave it up for that and other reasons. (I used to have to tap the plunger GENTLY to get it to top spilling lead from the spout on startup. I always had to put something under he spout to catch what lead did spill.)

[Tim Lyne]

Tony Bagdon described this in a bullet casting article he wrote for the N-SSA. I can't recall if he stated that this had happened to him or not; it could have been a warning of the potential for this to happen.

I think the idea of starting with an empty pot is akin to a shooter finishing an event with the last cap fired at the ground; let's just be sure we're safe.

I think the circumstances he described might be possible, but I've not encountered it.

Tim Lyne
Knap's Batt.
#2952V

[Maillemaker]

Seems to me it would be worthwhile to rig up some sort of swing-away "hat" or cover for the lead pot.

Steve

[Southron Sr.]

Dear Steve:

I have a 40 pound pot on my Master Caster. I wrapped a FIRE BRICK (NOT an ordinary brick) with aluminum foil, shiny side out and I place that over the top of the pot.

The aluminum foil reflects some of the heat back into the molten metal and IF I were to have a lead explosion, the brick would keep a lot of lead from flying out of the pot.

Back in the 1980's I did have a 25 pound pot of molten lead blow up on me because a drop of water accidentally got into the pot. Suddenly, the placid lead pot went "KER-WHOOSH!! Lead was stuck to the ceiling of the room and "splashed" on my face, neck, arms and hands. I was burned. I was wearing a shirt and pair of jeans that had to be scrapped because the lead stuck in the fabric. The "saving grace" is that I was wearing safety glasses-which kept the molten lead out of my eyes.

In other words, keep WATER and other liquids OUT of your molten lead.

As for a full pot of frozen lead "blowing up" while it is melting. I have been casting since 1962 and have always left all my lead in my pot when I have turned it off. I HAVE NEVER HAD A FULL POT "BLOW UP" WHILE THE LEAD WAS MELTING.

[Maillemaker]

That brick idea sounds good, Southron! If only to keep errant drips of sweat away from the pot!

Steve

[Ken Hansgen, 11094]

Thanks for the replies, guys. Guess I'll continue to start with a full pot, but continue to leave the area while it heats up (unless I ever experience one of those extremely rare explosions. (Then, after I get the lead splatters cleaned up....).

[Pat in Virginia]

I remember one article that I read a number of years ago that addressed this subject. What the author was saying was, if you leave your pot full of lead at the end of your casting session, it may be possible for water to collect underneath the lead. (There was no explanation as to how this process would occur as I recall.) Then when you heat the lead up again the water would be trapped underneath the lead and you would get a very exciting pot explosion.

I wonder if bottom pour pots might be more suseptable to this effect.

One of the things that stuck in my mind was a comment the author made that went something like this: "So, you've never had this happen to you. Well, how many times would you like for this to happen to you."

The thing I like about those words is that they have much broader applicability than this particular subject. And, that's why I remember the gist of that article.

Pat

[Bob Bumleg]

Never had that problem myself, but the "wet pipe" scenario is correct. Dangerous! Many years ago Doc Chambers and I were making ingots in my driveway and it started to rain. The driveway was nicely paved with a fine lead coat. We ran for the hills.

[Fearless Frank]

You and Doc Chambers ran?

[Lou Lou Lou]

This occurred in the last Century. I'm just sayin'

[MR. GADGET]

Had it happen one time due to a cold cast iron dipper being dropped in the pot to fast.
The Iron must have sucked up water out of the air in the shop. THe lead, pot and dipper were all in the shop for several weeks at the same temp before use.

[ms3635v]

I heat my dipper and mold next to the pot (propane fueled) while the lead is melting. By the time I am ready to cast, everything is at the proper temperature. If there is even a hint of rain I cancel my casting session.

[Scott Kurki, 12475]

You know those sneeze guards that there are on buffet tables at restaurants? It sounds like one of those sneeze guards might be an idea for a melting pot accessory. The guard would direct any material coming out of an exploding pot away from you.

[Kenneth L. Walters]

If your pot is full when you turn it off you can have a problem. The heating elements are in the bottom. Alloy down near the heating element melts first. As that metal turns to liquid it expands.

If the furnace cooled gradually then the metal will have hardened consistently throughout. In that case as the liquid expands it will push up on the top still hardened metal. In a furnace with a bottom drain, this pressure can actually push up on the still hardened metal and raise it. It will also raise the rod that seals the bottom plug. The furnace will start to drain. After that liquid metal runs out, even if only a small amount of it runs out, there is no way for the heating element to melt the remaining solid metal. You are going to need a blow torch. Been there. Done that. You can, incidentally, measure the distance that solid metal top plug raised up.

But if the furnace didn't cool gradually, it you added ingots, say, to cool the metal quickly, then there will be weak spots in the hardened alloy above the heating elements. In this case as the metal near the heating elements turns to a liquid and exerts pressure that liquid alloy will find those weak spots and travel up them. You've made a lead volcano. When that alloy "explodes" out of the top of the furnace it can sent a stream of liquid metal out that is up to a foot long. I've had that happen. Fortunately for me that metal stream missed me, but not by much.

More decades ago than I can now remember I wrote an article that I think the American Rifleman printed (I might be wrong about that because it was so long ago) where I talked about a furnace explosion. I was talking about metal exploding out of the top as I just described. The furnace didn't explode but the alloy did explode out of the top of the furnace.

All these decades later I still drain a furnace before I turn it off. Only leave a couple of inches of alloy in them. Just enough to cover the area where the heating element is.

[Southron Sr.]

Well, in almost 50 years of casting, I have had only one lead pot "Explosion." That was when I stuck a cold ladle into a pot of molten lead. As I learned later, the ladle probably had a drop or so of water on it.

Besides melting lead in pots on an old stove, I have used both a Lyman lead pots and two made by Magma Engineering. The heating elements of all of those commercial pots have the heading elements in the walls. This might account for the fact that I have never had a lead pot blow up while the lead is being melted.

[Ron/The Old Reb]

I too like Southern Sr. have been casting bullets for almost 50 years and have never had a lead pot explosion. I started out with a Sacco furnace that I sold a longer time ago and have been kicking my butt ever since that I sold it. I now have two furances a small Lyman and the 20lb Lyman. I always fill the furnaces to about one inch of the brim befor I shut them off. I never put lead pipe, mines picked off the back stop, wheel weights or any reclaimed lead directly into the furnace. I melt all this tape of lead in a pot on a gas stove and flux it well, skimming off all of the slag and crap and pour it into one pound ingots. Then as I am pouring bullets I preheat the ingots by placing them on the rime of the pot. This will evaporate any condensation that may have collected on the ingot. It all so lets the lead in the pot recover more quickly and you can keep on casting and do not have wait for the lead to come up to Temp.