Ingots appear bubbly on the bottom?

[Ferdinand]

I smelted and poured ingots into mini-muffin pans for the first time tonight. the ingots have bubbles or air pockets that formed during pouring and freezing. The lead was a mix of several types of ww. Any idea why my ingots looked like that? Thanks in advance.

[docone31]

Could be a lot of reasons.
The more you ingot, the smoother they become.
The warmer the ingot mold, the smoother they become.
Keep at it.

[sagacious]

Ferdinand,
Yes, this is common. There is almost always some microscopic amount of moisture present on metal surfaces. Preheat your muffin pan to about 150-200*F, and the bubbles will no longer appear.

Generally not a problem, but on occasion it can cause a splatter or a pop. It's always the safest practice to preheat any casting tools that will come into contact with molten lead.

Stay safe, and good shooting. :drinks:

[GLL]

Cast iron will do that for the first few pours if there is ANY rust on the surface. The rust is hydrated iron oxide which has a a fair amount of water tied up ! VERY rusty moulds can produce a small eruption so be careful with the initial few pours until the water is driven out! :)

I agree with sagacious about preheating the iron moulds for safety !

Jerry

[44fanatic]

My ingots do the same thing in muffin pans. Figure it is some sort of gas coming off the coating of the pan. I asked about it and experience from the members here say its nothing to worry about.

[lylejb]

trace of water or oil

I once used a mist of aero-kroil before storing my muffin pans, and figured it would just burn off once I used them again.

I was right, it did burn off, and left MOON CRATERS in the bottom of the ingots. Oh well, they all melt the same.