Gold coloring on Pb & smelting pot

[oldhenry]

I'm fortunate to have my own range only 100 yds. from the house. In my younger days I'd mine the backstop every 5-6 years, but now it's been over 20 years. At age 78 it's not as easy as it once was & my boys are grown & are not around to help.

Anyway: I mined about 4' of it recently. In the past I didn't go out of my way to gather the .22rf stuff, but after learning about 50/50+2 on this forum I've taken a new interest in Pb (formally it was strictly COWW). I don't shoot jacketed HG boolits, but friend occasionally deposit some into the backstop. The majority of the recovery consisted of: boolits I'd cast from COWW, .22rf & a very few J types from friend's guns.

I separated the cast from the others. I considered the J types & .22rf as pure Pb & my cast as COWW.

Smelting the cast boolits was uneventful, but when I began to smelt .22fr & J types the smelting pot top edge turned a yellow color. It had an almost powdery appearance. I was stumped @ this because everything melted came from a pure source.

After fluxing with paraffin & removing the impurities & empty J jackets, the remaining metal had a gold color. I could skim the gold off & see silver underneath, but when I removed the gold layer, more came to replace what I skimmed. The same situation happened when I fluxed with sawdust.

When I poured the metal into ingots (muffins in my case) the silver metal poured from beneath the gold film & the gold film remained on top & in the pot. The muffins look better than any Pb that I've ever recovered. It does not have the slightly purple hue that pure Pb normally has & has a shine similar to silver. The thumbnail test is consistent with Pb.

I suspect that the copper coating that is used on some .22 rf ammo may have produced the color, but I'm often wrong. If so: why did it return after being skimmed off?

Photos:
#1. .22 rf & J boolits in pot
#2. alloy after fluxing
#3. Pot after allo poured out: gold film remained in pot
#4. Pb muffins (they look good to me)

I welcome any explanation from forum members.

Henry
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A real sport involves either gasoline or gun powder.......all others are just games

[Walter Laich]

from a very old CB post: it is tin oxide and needs to be incorporated back in by fluxing

http://castboolits.gunloads.com/archive/index.php/t-63550.html

[oldhenry]

Walter,
Thanks for the info on the old thread.
There are several opinions expressed in that thread (it is long) that started off declaring the gold color to be tin oxide, but the opinions changed. Later, it seems that the gold color is an indicator of pure lead being heated @ too high of a temperature.

The later explanation makes plenty of sense, since the metal was for the main part melted .22 RF boolits with a small percentage of core material from jacketed boolits..........they should be as pure as it gets.

The gold appearance is actually an extremely thin film.

As a practical matter it proves that the metal is perfect for the Pb contribution to a 50/50+2 alloy.

Thanks again,
Henry

[Boolit_Head]

Not sure but they may be connected. You may have to overheat the pot to have the tin oxide seperate out. Maybe someone more knowldgable can confirm or deny?

[Rcmaveric]

Jacketed bullets actually have some antimony in them at abouts 1-2%. It helps with extruding of the lead. I have always been told the straw color is from tin oxide, i am only an under educated backyard scientist, so i just pushed the "I believe" button. I get it a lot while smelting. I smelt a lot of mininings from berms and do it with a thermometer so i know i am not over heating it. Those ingots aren't purple so they aren't pure. Most of what i mine from berms comes out 8-10 BHN and its mostly jacketed.

I have always tacken that straw like color as a good sign, it means there is some tin in my lead :)

[Dunkem]

I recently encountered the same persistent, thin, goldish yellow film you describe, except it was during my first attempt at smelting SOWW. These, from my research have been proven to be almost pure lead with little to no tin whatsoever. Due to this I don't believe the tin oxide theory is plausible. I also do not feel that my pot was overheating due to the facts that 1: I was struggling to keep the melt above its slush stage due to a stiff breeze and 2: after rigging up a make shift wind break and my burner still on "stiff breeze" setting the lead did develop some deeper, more vivid colors in the purple and blue range which I attributed these colors to a sign of over temp. Like you my attempts to flux whatever oxide was forming back into the melt seemed futile as is reformed as soon as it was skimmed. I just had to accept that this is the way pure lead is and started pouring ingots as is with the occasional dollop of the film falling from the ladle and making a messy looking ingot, on top anyways. Underneath the ingots were noticeably shinier than their clip on counterparts I've had more experience with, almost a chrome like appearance. I have yet to use this lead for anything yet so I can't speak for its performance yet. But with a Blackpowder mold in the near future and a hollowpoint modification project finishing up as soon as tomorrow, I'm looking forward to putting some to good use.

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[Rcmaveric]

Mettle in its molten state will oxide almost emediatly. Expessially tin is the first one to oxide followed by the other elements. That oxide film once formed will not penetrate any deeper. Skiming it off though will deplete the alloy content because once removed it will just reform thus leaching out your all.

A lead alloy can be of anything. But i have never experienced it with stick on lead or lead sheeting. Pure lead will have quite beautiful purplish blue when molten and cast into bars. If doesnt have those hues and glass smooth then your lead is not pure and is alloyed with something like tin and antimony. It is very easy to tell the difference between a pure lead ingot and an alloy.



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[oldhenry]

I appreciate all of the responses.

Boolit Head,
You could be correct. My smelting apparatus is primitive. I do it over a Coleman stove that looks like it was in WW1 & WW2. The pot & heat deflector is a Lyman product that I bought in '60 (I cast many boolits from that pot with a Lyman dipper before I got a bottom pour). With this setup there is no temperature control & I'm of the opinion of the temp being OK if it melts whatever is in the pot.

Remaveric,
Good to know that jacketed cores contain 1-2% Sn . Next batch of .22RF boolits, I'll not include any jacketed. I'm interested as to whether this will change the outcome.

Dunkem,
Thanks for your response.........it's good to hear of an experience exactly like mine.

Henry
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A real sport involves either gasoline or gun powder.......all others are just games