lead question

[the skrat]

i opend my box from track of the wolf the other day and in it was a lee melting pot ingot mold and 490 round ball mold i had a 45 pound chunk of lead and i chiseled off a couple of pounds melted it cleaned the scum off and poured it in my ingot mould so then today i melted it again and poured a bunch of round balls thinkin this is a lots of fun but my one question is there always seems to be a thin layer of scum no matter how much i clean it is this normal what is it impurities or could it be the cold air contacting the suface just wanna know. this is a bottom pour pot so i would guess the lead coming out would be a lot cleaner and i also use a little bees wax the lead has been around the house 25 years or so from when my dad used to pour downrigger weights seems fairly soft can scatch it with finger nail but its of unknown origin.

curly maple

 

[Gordon Horn]

I use the same melting pot to pour roundball and even after cleaning the melted lead it seems to have a tarnished look to the surface. I don't worry about it. I always leave lead in the pot anyway, to protect the valve.

 

[MikeChapin]

I wouldn't worry about the scum on top, it's probably just oxidized lead. When the hot lead hits the the atmosphere it oxidizes pretty fast but the film prevents more lead from oxidizing the same action that prevents aluminum from desintegrating.

Since you're using a bottom pour pot I would not worry about it. When you add new ingots, any oxidation on the outside of the lead will float to the top when melted. Just skim it off when it gets obnoxious. You will notice when you skim it that the stuff if not near as dense and much more brittle than pure lead.

I use a regular lead pot on an old buffet range and have to skim several times during a session because the stuff gets all over the ladel and plugs the drain hole.

 

[the skrat]

thanks guys kinda what i thaught but being new to pouring lead i just wanted to make sure. :front:

curly maple

 

[Slamfire]

If there is much tin in yore lead, it'll float to the top and take on a scummy appearance. Since you want soft projectiles, let it happen. If you wanted real hard alloy, you'd have to flux and stir quite often. :front:

 

[Stumpkiller]

It's normal. I'm always amazed in what floats in lead. LOTS of things float in lead. Iron, tin, silver, zinc. Heck, gold will float in lead. All the impurities are called "dross" and float to the top. I have a stainless steel tablespoon with a dozen 1/8" holes I drilled in the bowl to skim the crud off. Even when I re-melt ingots of once melted & poured lead I get more dross. I knock it into an old paint can and take it to our fire house when they have hazardous materials collections day

 

[Slamfire]

Antimony don't float out it combines with the lead at a molecular level. A good reason not to use chilled shot for a lead source. :nono:

 

[the skrat]

thanks guys all i want to pour is roundballs so i guess the more pure the lead the better hey stumpy just wondering why gold would float in lead isnt it close to being twice as heavy just curious. i do a little gold panning if i ever find enough now that would make an awesome roundball. :front:

curly maple

 

[Stumpkiller]

Gold (Au, #79) has an atomic weight of 196.9665

Lead (Pb, #82) is 207.2, or 5% heavier than gold.

The Lone Ranger's silver bullets weighed about half what a lead bullet does, that's what made him so quick. :winking:

But, gold is gold in the wild. Lead is in the form of galena (lead sulfide) or other impure ores and weighs less because of the molecules in total, not the elemental molecular weight.

In the melting pot, lead is 97 or 98% pure.

 

[jim gray]

Stumpy you are correct about the atomic weights, but I think that the relevant characteristic here is density.

gold = 0.6972567 pound/cubic inch
lead = 0.4107673 pound/cubic inch

If your gold floats in lead, I think you got ripped off. :haha:

 

[Stumpkiller]

If your gold floats in lead, I think you got ripped off.

The only gold I got is one upper tooth and my wedding ring. If either of those are found floating in molten lead, it won't matter.

 

[Slamfire]

If the second one is found first the first one will soon follow. :crackup:

 

[dryfly]

Flux it.