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Old February 4, 2013, 01:49 PM   #26
maillemaker
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I don't know of any way to separate the tin from a lead/tin alloy.

You could "dilute" the alloy by melting with more lead, but that might take a lot of pure lead to do, and you could be shooting the pure lead.

I spent the weekend rendering a bucket an a half of wheel weights. This batch was pretty good in that most of them were actually lead. I had a few zinc ones and a few ones marked Fe that did not melt.

I run my pot at around 700 degrees F so I do not have to worry about the zinc melting in.

Steve
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Old February 4, 2013, 03:38 PM   #27
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Dilute with pure lead (what's the point in that?)
Or trade for pure lead with a smokeless shooter who would actually like the harder lead.
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Old February 4, 2013, 04:08 PM   #28
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"Or trade for pure lead with a smokeless shooter who would actually like the harder lead"
Thought about that, I'll keep that thought in the back of my mind.

I've been doing a little reading about fluxing and here's one of the first links I followed:
http://www.lasc.us/FryxellFluxing.htm
a reprinted article from glen fryxell, interesting read...
Here's a quote from that article...
"Let's look at what a flux is expected to do, and how some of the different fluxes work. When we melt a pot of bullet metal, we have a high temperature pool of liquid metal in contact with the air. The oxygen in the air slowly oxidizes the metal at the interface; the hotter the metal, the faster this oxidation takes place. Since this is a heated liquid pool, convection leads to rapid turnover at the surface of the liquid, and the more easily oxidized components of the melt are preferentially oxidized as this mixing takes place. The resulting oxides are almost always insoluble in the molten alloy, so they tend to separate and form a separate phase. In the case of bullet casting alloys, tin is more readily oxidized than is lead, so the tin oxide forms a "skin" across the surface of the melt.

Some of the other metals that may be present as minor impurities are even easier to oxidize, and "follow" the tin up into the "skin" (lead is pretty dense stuff and most all of these oxides are of lower density, so they float)."

Now that got me to wondering, if I don't flux the pot and I just let the metal at the surface skin up a bit as the oxides form and then skim the surface ...am I going to remove enough of whatever mystery metal is alloyed with the lead to give me a more pure pot of lead?
Doc?
Hawg?
Whaddayathink?
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Old February 4, 2013, 05:29 PM   #29
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Possibly, but you will have to keep skimming the dross to allow more oxide layers to form. I would think the oxide layer on a still pool of lead would prevent further oxidation from taking place.

Steve
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Old February 4, 2013, 05:43 PM   #30
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I kind of came to the same conclusion, thinking that the oxide layer could only get so thick before it cuts off the oxygen from the metal pool underneath. So to get rid of some of the unwanted harder "stuff" in my lead mix, it looks like I'm going to try skimming and skimming and then skim it some more.

I've downloaded fryxell and applegates book from this link and am skimming some of the "more interesting to me" places
http://www.lasc.us/Fryxell_Book_textonly2.pdf

Seems to focus more on casting for the purpose of loading into a cartridge case but still has some interesting information on lead alloy properties. Looks like once you alloy it, it can be hard to undo...

Am starting to wonder about a borax based flux? From what I've read it looks like those tend to take everything out of the mix by creating an insoluble molten borate glass on the surface of the metal pool. Reckon that's more trouble than its worth or the path to softer lead?
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Old February 4, 2013, 09:22 PM   #31
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skimming

an old timer back in the 70's and a book he referred me too suggested fluxing lead with canning parafin. Drop a teaspoon sized chunk on to the melted lead . Be careful it can flame up.
Gently stire the pot.
Keep skimming the the dross to get all the impurities out. Cast into an ingot and test.
I usually just tested with the fingernail as he showed me,
Back in the day I would use nothing but the stick on wheeleweights as back then they were almost pure lead.
As we now know this isn't true today.
I got a scrap yard that sorts the pure soft lead from other leads.
They sell at the going market rate for the day. Last week 95 cents a pound.
Going to start stocking up.
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Old February 4, 2013, 11:41 PM   #32
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I really think you are going to end up skimming away oxidized lead more than anything, until you've skimmed away your pot of lead!

You'll have no way to know when you've skimmed enough.

I think a better bet is to trade your hard lead for softer lead.

Steve
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Old February 5, 2013, 01:23 AM   #33
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Fluxing and skimming repeatedly will get you nowhere near UN-alloying your metal.

I once spend well over an hour trying to do something similar. I was trying to see if I could ever flux to the point where there was nothing to skim. I found out the hard way all I was doing after the first couple of fluxing and skimming, all I was doing was skimming oxidized lead. A futile attempt at purer lead.

My understanding is once alloyed, it is impossible to UN-alloy metals with what we normally have for our home shop.
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Old February 5, 2013, 09:06 AM   #34
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My understanding is once alloyed, it is impossible to UN-alloy metals with what we no

Rigmarol,
From what I read online last night about lead smelting on an industrial scale, I think I agree with you. Looks like un-alloying is out of reach for the average joe casting shop that most of us run out of our garages and outbuildings.

I've been shooting up some round balls that I cast myself back in the fall and it's about time to do another casting run, I'm out of conicals too. I've got 15lbs of lead that is supposed to be plumbers lead and soft (right now its in the fish ingot form waiting for the casting pot) and I've also got probably 20lbs of harder stuff that has a mystery metal alloyed with it...dude first told me it was pure and then changed the story when I cast some round balls that couldn't be rammed into a 58 remmy chamber. I've been casting the harder stuff into rifle bullets with a "lee modern target design minie bullet mold" I picked up at cabelas, and they shoot good so I think I'll just make me a good supply of rifle slugs for the old inline. Since I shoot the revolver more than the rifle I was just wondering if it was even possible to soften up lead somehow.

I might be willing to trade some of the harder/impure lead I have for pure lead, if anyone is interested PM me and we can work something out.
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Old February 5, 2013, 10:20 AM   #35
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skimming

I didn't mean to suggest you could ever get it all out.
My post was based on normal old time stick on wheel weights where they were close to pure lead.
The impurities will float to top without fluxing, but fluxing does help.
But because tin and antimony melt at higher temps than lead and are lighter, these will over time with and without fluxing float to the top.
Will you ever get them all out of a pot, ,,,,,,,,,no.
But you can skim off quite a bit.
The only time you should have lead oxidizing and forming a crust / skim is if you are not smelting at the correct temperature. Use a thermometer.
Good clean pure soft lead at correct temp, should have very little skimming.
Of couse there will always be a very fine discolored skim. That is usually just the lead it self that has cooled on the surface of the pot.
The nastier stuff you want out is thick heavier and more crusty and will solidify almost instantly when lifted even a fraction of an inch from the surface.
But will you ever get a pure lead smelt at home from a mixed alloy? no.
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Old February 5, 2013, 10:42 AM   #36
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Quote:
The only time you should have lead oxidizing and forming a crust / skim is if you are not smelting at the correct temperature. Use a thermometer.
Good clean pure soft lead at correct temp, should have very little skimming.
Of couse there will always be a very fine discolored skim. That is usually just the lead it self that has cooled on the surface of the pot.
I'm not sure this is so.

Lead oxidizes just sitting solid on your desk, and quickly at that. It's why your bullets turn from silver to gray.

Heat accelerates oxidation.

I usually cast at around 750F. But as soon as my lead melts and you skim the dross, the lead on the surface begins to oxidize. It starts off with discoloration, but if you skim this you will get a dusty dross residue.

I see this even with 99.9% pure lead ingots.

Steve
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Old February 5, 2013, 11:27 PM   #37
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Steve I agree 100%

I flux 2 or 3 times on a 20 lb pot. I use gulf wax and ignite it while stirring the mix while scraping the bottom and side aggressively. All the "crap" is released and floats to the top to be skimmed off with my tea strainer. Lead goes through the strainer and the dross stays out to be dumped. Once you get to the point where it's just oxidized lead it's obvious you're done.

Once two metals are alloyed, they are molecularly one. There is no settling of the pure lead and floating of the lighter tin or zinc or Linotype (which is another alloy itself). It's not like water and oil.

I'm no expert, this is just my understanding.

Last edited by Rigmarol; February 6, 2013 at 09:08 PM.
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Old February 6, 2013, 09:13 AM   #38
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Quote:
Once two metals are alloyed, they are molecularly one. There is no settling of the pure lead and floating of the lighter tin or zinc or Linotype
After doing some reading about alloys, I agree. Looks like separating the lead out of a lead/whatever alloy is like separating the white out of a cloud. I found a good description here:
http://en.wikipedia.org/wiki/Alloy
Quote:
An alloy is a mixture of fairly-pure chemical elements, which forms an impure substance that has the characteristics of a metal. Alloys are made by mixing two or more elements; at least one of which being a metal. This is usually called the primary metal or the base metal, and the name of this metal may also be the name of the alloy. The other constituents may or may not be metals but, when mixed with the molten base, they will be soluble, dissolving into the mixture.
The article seems to be saying that the atoms of the components of the alloy disperse themselves evenly within the mixture and it becomes homogeneous in consistency. Thats not to say that oxides of one or more of the components of the alloy don't form when heated in the presence of oxygen and become a non-soluble substance that will float to the top if it is less dense than the alloy.

Wrapping my mind around this, it looks to me like the oxides will form and float, since lead is denser, and you can skim them off...but you'll never get all of the "impurities" out of the mixture because the atoms of the metal you don't want are evenly distributed with the atoms of the metal you do want.

Am I understanding this correctly or have I missed something obvious? I'm no chemist, or metalurgist...

I guess I'll be casting some rifle bullets out of my alloy...you can never have too much ammo anyway.
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Old February 6, 2013, 03:57 PM   #39
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Logan5579, you're right. Once the metals are alloyed, us garage metallurgists aren't going to separate them into their constituent elements. In liquid form, the atoms tend to disperse evenly throughout the mixture and in solid form, the impurities (like tin) substitute themselves in the matrix for atoms of the base material (lead).

As far as oxides, fluxing and skimming goes, the idea behind it all (as Fryxell discusses in his excellent guide) is to flux to draw the organic impurities out of the melt, then skim those impurities (as well as extra stuff like steel clips, etc.) from the surface of the melt. If you're using a bottom-pour furnace, then you shouldn't have to skim again. A layer of oxide will form on the surface which will protect the bulk of the liquid from further oxidation.

Beyond that, I'd just say refer to the online guides mentioned by the OP because they're some of the best information you'll find.

Oh, and I've found that the stick-on wheel weights aren't pure lead. They're definitely harder to load than store-bought balls, but not enough to fuss over.
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Old February 6, 2013, 09:57 PM   #40
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logan skimming / alloy

I was trying to say the same basic thing. just in a confusing way.
Yes given time and the right temp, some of the alloy metal will separate from the base metal.
It along with the other impurities will float to surface.
But no you will never get all the alloy out at home And not likely enough to make any real changes in the mix, but you will get some out. That's why with traditional M/L's you should use the purest lead you can. Although some tin etc really won't hurt much.
The real fine skim of discolored oxidation that forms I never skim off.
I stir the pot and surface everytime I dip into it.
Doesn't appear to affect the quality of the cast.
I only skim off the heavier dross, that crusts up.
I too only flux a pot 2 maybe 3 times. Unless I am still getting a lot of nasties and that's rare.
I top my pot off with fresh lead when it is about 1/2 empty and of course flux the new stuff.
But as in all things, you got to do what works best for you.
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Old February 7, 2013, 09:56 AM   #41
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Thanks for the input guys, I enjoy learning new stuff from people who have been there/done that/got the pictures to prove it!
Saved me the trouble of melting and skimming a bunch of alloy for no useful end result
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Old February 7, 2013, 10:35 AM   #42
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Just a quick tip for the beginners; Casting really should involve two seperate and distinct melting operations if you are using mystery metal or scrap or even Wheel Weights.

1. Make ingots first - don't start casting bullets by dropping your scrap/scrounged lead into your actual bullet casting pot.

Instead, get or make yourself a larger cast iron dutch oven pot or cut a BBQ propane tank in half and use a turkey fryer propane burner to melt your scrap/scrounged lead in.

Take out all your floaters (clips, zinc, screws, rocks, and such) then flux a few times stirring and scraping the bottom and sides aggressively.

Scoop out the dross and ashes and such then pour your lead into approx 2lb ingots using whatever you can get. I like the older 1 piece muffin tins. I find them at yard sales or thrift stores (don't use modern muffin tins. They solder the cups to the flat part and your lead's heat just melts them and they come off.)

2. After you have a good pile of ingots, take those to your nice clean electric pot or a smaller pot over propane, and repeat the melting and fluxing. You will still get some "crap" in your melt that comes out when you flux but FAR LESS than if you start with your scrap/scrounged lead.

I made some pretty bad bullets my first time... someone set me straight with the above advice and I'm just passing it on.
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Old February 7, 2013, 11:07 AM   #43
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My muffin tin has separate pieces to make the pockets, but I have had no problem with them de-soldering - maybe they are welded on?

But this made me think of another tip: don't use tin-plated muffin tins. The lead will alloy to the tin and will not come out of the mold. You'll have to cut it out, destroying the muffin pan.

The guy who taught me how to cast showed me a tin like this with the ingots permanently in place. I was able to teach him what caused it because I had read about it on the web before my training session.

Steve
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Old February 7, 2013, 12:29 PM   #44
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hmmm...heres another question: I've been using a stainless steel pot as my casting pot, which is better cast iron or stainless? I've used both and the stainless heats much more quickly...there shouldn't be any alloying going on with my casting pot since iron/steel needs nearly 2000 degrees to melt, right?
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Old February 7, 2013, 01:21 PM   #45
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The material of the pot probably doesn't matter. I think the cast iron pots work well because they are very thick and thus hold heat well.

Steve
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Old February 7, 2013, 01:39 PM   #46
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I had forgotten about the tin muffin pans!
I had one do that to me once as well. I'd forgotten about it. Good tip.

As for pot material, I'd stay away from aluminum sauce pans.
I stole an old one from the kitchen and after about a year, the bottom began to sag bad enough that it would not sit flat on the coleman camp stove I'd been using. I doubt it would have ever broke open or melted, but it did deform badly. I went to a steel pan and shortly after went with an electric melting pot.

My ingot making pot has always been a large cast iron pot with a lid. I thought about using the stainless pot that came with the turkey fryer burner but it was so hand to user for.... well, frying turkeys... who'd have thought?
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Old February 7, 2013, 02:27 PM   #47
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Last weekend I was rendering wheel weights using my burner and my dutch oven, and it was cold out, so it was taking a long time to melt and sustain the melt.

So I took some sheet metal and formed it into a big loop, making a shield around the whole pot. As it was burning on the burner, I also took a big wad of fiberglass insulation and laid it on top of the pot, mostly filling the "baffle" I made to surround the pot.

This lets the heat that rolls off the bottom of the pot surround the sides of the pot. More heat goes into the lead and less out into open space. This drastically improved the melt time, which saves gas.

Steve
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Old February 7, 2013, 03:46 PM   #48
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Quote:
Originally Posted by rigmarol
Take out all your floaters (clips, zinc, screws, rocks, and such) then flux a few times stirring and scraping the bottom and sides aggressively.
Flux first, then remove the floaters. The reason that I say that is because during the smelting process, some tin will leach (this is probably the wrong word) out of the melt. You don't want to discard the tin with the dross, so fluxing first, then skimming will make sure that you've both reduced the tin and separated the contaminants.
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Old February 7, 2013, 05:06 PM   #49
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Hardcase, good advice, no argument from me on it at all.

However, my technique involves a French Fry spoon that is impossible to take away any tin or "good stuff". So I'm not wasting flux on the trash.

Here's some of my Ingot casting tools:

Starting with Wheel Weights my turkey fryer and cast iron pot:



French Fry spoon to get the trash out:


Fluxing with Gulf Wax. Yes it ignites, that's ok.




Stir and scrape the bottom and sides agressively then remove using a tea strainer. The lead goes right through it leaving the "bad stuff" in the strainer:


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Old February 7, 2013, 05:07 PM   #50
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The French Fry spoon


The Tea Strainer


The Results:
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