Emptying your lead pot at the end of each casting session

[Kenk]

Was reading about a guy that would  always empty his lead pot at the end of each casting session because reheating the pot could cause an explosion. Has anyone experienced this, or read about something like this happening? Below is what the guy said

?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. He advised always emptying the pot before cooling?

[Kenk]

After extensive searching, I?m finding little to nothing on this pot blowup phenomenon.

[John A.]

Only time my pot has ever been empty, was when I first took it out of the box.

I don't tend to let it cool while it's full or anything, but there's almost always some lead in the bottom when I finish, which I let cool and it hardens.  It warms back up and melts the same the next time you start casting.

This is probably one of those "to each their own" deals.

[sqlbullet]

I am the opposite.  Last step for me is usually to top the pot up to about 90% full. 

My thinking is two fold:

1.  I clean the lead just before the heat goes off, and there is very little space in the top for dust and crud to accumulate between sessions.
2.  Lead to wall contact is maximized which in theory should increase efficiency when heating the pot from cold.  Haven't done the math or any empirical tests to validate that.

Lead does expand as it heats, but the hot lead just "perspires" out the top in my experience.  Perhaps a eutectic alloy might cause an issue, but I doubt it.  Reason being, it should also shrink as it cools.  So any contraction after the mass passes solidus creates space for the same expansion when the mass expands before it crosses solidus on the way back.

[James8719]

I am the opposite.  Last step for me is usually to top the pot up to about 90% full. 

My thinking is two fold:

1.  I clean the lead just before the heat goes off, and there is very little space in the top for dust and crud to accumulate between sessions.
2.  Lead to wall contact is maximized which in theory should increase efficiency when heating the pot from cold.  Haven't done the math or any empirical tests to validate that.

Lead does expand as it heats, but the hot lead just "perspires" out the top in my experience.  Perhaps a eutectic alloy might cause an issue, but I doubt it.  Reason being, it should also shrink as it cools.  So any contraction after the mass passes solidus creates space for the same expansion when the mass expands before it crosses solidus on the way back.

I do the same! Been casting for 45 years and have never experienced and "explosion" from reheating a pot filled with lead. I've used cast iron pots and both Lyman and Lee pots.

[Kenk]

Thanks, I figured if there was any truth to it, there would be an abundance of warnings out there

[marlin39a]

I unplug, and dump all the spru cuttings in the pot.  Have been doing it since 1977.

[Kenk]

Thanks guys