Oh no...is this zinc?

[groundsclown]

Did something that I've never done before while smelting. Got distracted!

Had a pressing phone call, lost track of time & 45 minutes after I'd normally check my pot, I remembered I had a pot cooking.

Temps to high, I know. I see the gold color. I hand sort all my WW's so if there's any zinc in there it's minimal. Fluxed, stirred, stirred, stirred, fluxed again & stir stir stir. Getting this sort of "scum" floating up though. Not a full on oatmeal consistancy but sure dont look right.

edit: fluxed with pine shavings & lube from several handfulls of boolits I threw back in the mix.

[groundsclown]

So I stirred & fluxed, threw the lid on & shut everything down & let it set up (starting to cloud up like rain)
Of course the top is a purple'ish hue from the heat but smooth on top. No lumpy oatmeal texture which I thought for sure would happen once cooled.

Think I dodged one? I'm feeling better that the tops smooth now that it's cooled.
Tomorrow I'll fire it up again only this time shutting off the phone, then keep a closer watch as it comes up to temp & see if it gets lumpy.

[sqlbullet]

I think that is just a bunch of oxidized lead, antimony and tin that occured with the high heat. I would heat it back up to about 750 and flux it good with sawdust and used motor oil, cause that is what I use.

I think you will be fine.

[bangerjim]

As said above^^^^^^^^^^^ too hot for too long.

Just remelt and flux/reduce well at a LOWER TEMP (!!) and you should be OK.

banger

[groundsclown]

Just a quick update.
I remelted & things turned out ok. My best guess, like mentioned above, is it was a lot of oxidized lead from leaving it unattended to long.
Brought it back up to temp, fluxed a few times for good measure & poured ingots. All was smooth with no lumps...+1 for hand sorting!

[Walter Laich]

A friend does the smelting and I do the casting. When he first started he used the fires of hell to melt the scrap
.
I was getting a bunch of zinc in the ingots.
.
maybe I was lucky but just skimmed it off and didn't seem to affect the bullets I was casting. I was using a bottom pour pot that might have been a factor

[bangerjim]

DO NOT get uptight about zinc! It is not as evil as some think it is. A small amount does NOT ruin your melt as has been said falsely on the net!

I have intentionally contaminated pure lead with up to 5% Zn to see the results. Took a much higher melt temp to get it in there, so there is your 1st preventative step......keep temp below melt point of Zn. Zinkers will float on the top with the steel clips and gunk.

I saw no real degradation in castings at 1-2%. Above that, fill out was starting to suffer, so I added more tin and problem solved! Weight did go down a bit. Since tin is at a premium $$ these days, it is best to avoid having more than 1-2% tin in your soup. Keep your smelt down below melt point of Zn. (are you seeing a theme here?!?!?!?!?)

Tin lowers the surface tension of molten lead and allows it to flow into the "nooks & crannies". Zn raises it, so I have been told, and lessens fill out. Ever wonder why you do not see a lead/zinc alloy for wire solder? Would definitely be cheaper than tin.

A small quantity of Zn (a 1" WW) in your smelting pot of 50-100# of lead will not "ruin the whole batch"! But keep the temp below melt point of Zn and you will be OK! Watch for floaters.

Bottom line........temp.......temp........temp!


banger