Bubbling lead question.

[Inkman]

Watched plenty of videos and read plenty of threads here trying to find the answer so maybe just asking outright will help.

Adding muffin pan ingots to my Lee 20# pot the other nite as i was in the middle of casting. Always pre heat them on a griddle. No moisture is around and they are stored in the garage. Nor Cal here so there is not much, if any humidity. This is all range lead melted into muffin ingots anywhere from several months ago to over a year ago. All ingots from the same batch. Absolutely no signs of oxidation on the ingots.

So, the thing is, is that even though i pre heat them on a 400 degree old pancake griddle for a loooong time, i had two out of maybe 30 or more that when i eased them into the pot, they started bubbling pretty well. Bubbling enough that i ran for cover FAST. But that was it. If there was moisture IN the muffin to cause boiling/bubbling, why didn't it go boom instead of just bubbling visciously?

Now i've read enough about the water under the melt and explosions, tinsel fairy, steam and water ON the ingots. These are very dry. When i pour them while smelting, it's always one pour, not layered pours to form each muffin ingot.

Any ideas? Could there somehow be moisture inside some of them? Why only 2 muffins out of so many? All stored in the same place, same batch so why not have it happen to others?

I'm really kind of stumped.

Al

[gunseller]

Just throwing out an idea. Something that was on the outside of the ingots that turned to gas when heated over 400 degrees. Some type of chemical reaction.
Steve

[**oneshot**]

Were the ingot molds dirty/rusty, could have trapped some rust flakes in the ingots when pouring. I've noticed that rusty clips on coww's bubble a little when smelting.

[theperfessor]

Any chance there was an oil film or deposit on an ingot? Oil will out-gas like steam but isn't nearly as explosive. Maybe oil from handling with a greasy glove or something? Just guessing here.

[chris in va]

I get the bubbling as well. Nothing has ever exploded from it, I just keep on casting. One trick is to make the ingots really thin, about 1/2" at the most.

[44man]

Sounds like some air inclusions in a few ingots.

[bruce381]

I'm in Nor cal also and I get that too, my ingots are in a cabinet in the garage stored at floor level I figure it is some condensation on cold ingots when i take them out from my hands or the air. They just bubble for a few seconds but I do run.

[I'll Make Mine]

Sounds like some air inclusions in a few ingots.

This is the #1 likelihood, IMO -- your ingots have air in them (rough iron surface in the ingot mold combined with lead that's not much above melting point can trap a lot of air in the metal), and when the ingot melts, that air is released to form bubbles. If they were from oil on the metal, they'd be filled with smoke and/or the bubbles would catch fire when they burst (molten lead is plenty hot enough to ignite most oils). If they were from water carried deep into the melt by the ingot, there'd be a lot more activity than a few bubbles.

[mold maker]

An ingot poured in a hot mold will solidify on the top surface and shrink in the inside. This draws air in under the surface of the ingot, during the slush stage.
Even though pre-heated to near 400 the air still exist inside the ingot. When dropped in the hot melt the surface melts first effectively sealing the captive air and only releases it as the center starts to melt.
There should never be more than a slight boiling/bubbling , and will disappear long before the solids totally melt.
It took me years to get used to, and understand the effect.
As a general rule, a tinsel fairy visit will be almost over before you can react, but it wont stop the jump. After her visit, you'll flinch at every reaction for quiet a while.

[olafhardt]

Oxides in the ingots can age to form carbonates or hydroxides which can give off CO2 or H2O when heated.

[williamwaco]

I see this VERY rarely.
My ingots are cast with the Lyman ingot mold.

I believe it is air but I don't ever expect to know for sure.

1+ for 44MAN

.

[Inkman]

Sounds like some air inclusions in a few ingots.


This is the #1 likelihood, IMO -- your ingots have air in them (rough iron surface in the ingot mold combined with lead that's not much above melting point can trap a lot of air in the metal), and when the ingot melts, that air is released to form bubbles. If they were from oil on the metal, they'd be filled with smoke and/or the bubbles would catch fire when they burst (molten lead is plenty hot enough to ignite most oils). If they were from water carried deep into the melt by the ingot, there'd be a lot more activity than a few bubbles.


An ingot poured in a hot mold will solidify on the top surface and shrink in the inside. This draws air in under the surface of the ingot, during the slush stage.
Even though pre-heated to near 400 the air still exist inside the ingot. When dropped in the hot melt the surface melts first effectively sealing the captive air and only releases it as the center starts to melt.
There should never be more than a slight boiling/bubbling , and will disappear long before the solids totally melt.
It took me years to get used to, and understand the effect.
As a general rule, a tinsel fairy visit will be almost over before you can react, but it wont stop the jump. After her visit, you'll flinch at every reaction for quiet a while.

You guys described it perfectly. It doesn't bubble as i ease it in and there is no smoke or steam, but as it is almost all the way in, so air in the ingots sounds like the culprit.

Completely different than the time last year where i was casting outside on a cold nite and moisture condensed on the ingots that were laying out and not pre heated. About a quarter of the way in they started sizzling and steaming from the condensation. I assumed i didn't get a fairy visit because the moisture just burned off as the ingot melted it's way into the pot (at that time i was using the long ingots that stuck up about 6 inches or more out of the pot). That is why i asked, since the bubbling this time was completely different than the experience i had last year.

Thanks peoples!! I feel better about it now, but i'll still probably run when/if it happens again!!

Al

[Inkman]

Thanks again for the help folks. Just another reason i tell people who say they want to start casting their own to get on this forum and read, read, read before even thinking about buying any equipment to start casting. There is soooooo much info here and the members are sooooo helpful. Takes a while to soak it all up but this site is a wealth of knowledge.

Al

[milrifle]

I had something similar happen to me. I had some ingots in a coffee can that got left outside and partially filled with rain water. Obviously, I dried the ingots off and stored them inside. After several weeks, I dropped one in my pot and got the same scare you guys are talking about, but it never got violent, just bubbled. I think I have two more of those out there, but every one of them did the same thing. I just assumed some moisture had crept inside 'pores' or something in the ingots. They are discolored, so I can believe the chemical reaction to some deposit on the surface, too. Maybe rust from the coffee can?

[prs]

Here in the foothills of the Appalachians, it is generally humid. I always "know" my muffins are wet. So I grasp them with a vise grip plier and lower them into the caldron slowly. Bubble, bubble, toil and trouble.............. ;-)

prs

[Alan in Vermont]

I never saw this phenomenon until started using cornbread wedge pan for my ingots. I had misted them with a squirt bottle to get them to cool faster as I only had the one mold. I think that cooled them fast enough to make voids which held air inside. They would bubble but not the violent eruption you get from trapped water. Maybe the size of the ingot makes the "happening" more likely, I don't remember ever having it happen when I was casting in molds that made only a 1 lb +/- ingot.

[marlinman80]

I'm in georgia and my range recovered lead bullets do bubble in the pot when i put in an ingot made from them. I melt all these bullets in a lrage pot outside over a cahrcoal fire on my forge. I dip 1# ingots off the top with a ladel after it has been well stirred and drossed. my temps 650 degrees and they are kept inside after cooling in a metal bucket with a lid. Everytime I reheat them to add tin or linotype they bubble pretty good. I always just assumed it was borax or some over mineral we have down here that gets melted and released while heating my lee production pot up. It gets hotter than my coal fire does. Huh maybe I should clean my lead at a higher temp. Also if you pour hot lead into a cold cast iron mold they get frosty to the core which means they are pourus and can suck moisture out of the air into themselves which can accumulate because lead is more conductive in air and therefore condenses water like the outside of a cold beer can. Maybe I should preheat my ingot moulds Just thinking