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We might have got some zinc in the mix????


Mustang Gregg

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I wanted to try out a new Lyman mold this morning.

And I grabbed a couple of ingots that were supposed to be made of the old tire wheel weights and solder. 

There was not supposed to be any zinc weights in them.

Well, the crap melted at a very high temp---the dross turned blue---didn't want to flow out of the bottom pour nozzle---and the bullets were about 15 grains lighter than what lino out of that mold should be.

I have only ever used wheel weights [the old ones], linotype, and solder.

So this was a new experience.

Do you reckon that there was zinc in the ingots?

 

Mustang

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Melted out some old wheel weights and had the same problem of purple blue lead with grainy texture.  Stumped any one a asked until recently.   Guys claim it's babbit.   Still not sure if they are right.  Never seen this in 45 years of scrap lead casting but the last 2  twenty lb batches came out bad.   Hope somebody can help.  But this is a great place for people helping.      GW

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Much obliged, GW.

I still have a load of it to try.  Or maybe it will go to the scrap yard.

Oh yea, besides running light weight, it is as brittle as lino.

 

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I have about 150 lbs left of this container.  Hate to throw it away cause lead reserve is getting low after couple of thieves got 1500 lbs out of shop (along with tools and other stuff) a couple of years ago.      GW

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Yep, I recently lost several "soft" sheets out of the barn. 

I reckon they were probably pure lead.

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That mix will probably work ok for cartridges, but will give a person fits in percussion revolvers, so don’t make revolver balls with it.

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With Zinc in the alloy:

Higher melting point than normal.

Alloy is harder than normal AND lighter than normal.
 

And with Calcium contamination:

Dross lumpy like oatmeal and won't break through to the surface cleanly, except with flame played on it.

Will plug the bottom pour spout unless you run pot 75-100 degrees F higher than normal.
 

 

Yep, all those would be indications of either Zinc (from Zinc wheelweights) or Calcium (from maintenance free battery lead) contamination.   Sounds like quite a bit in the metal if you see a big increase in hardness and brittleness.

 

Quote

Do you reckon that there was zinc in the ingots?

 

My guess, yep.  Quite a bit.

 

Folks have claimed they have removed Zinc by stirring in small amounts of "flowers of sulfur" (which is powdered sulfur), which makes zinc sulfide of the zinc, AND EMITS a large cloud of sulfur dioxide gas (a lung irritant and precursor to making sulfuric acid).  I've never tried, due to those side effects.

 

Almost no way to remove Calcium from lead alloys without expensive treatments.  Although I have made some amount of cleanup by adding high-antimony lead (like linotype) to the mix, and converting the Calcium to an  "intermetallic mix" of CaSb.   That dross then has to be handled REAL carefully because it will form Stibine gas in moist air (a poisonous gas used in killing rats and also during WW I).

 

For most purposes, casters just should sell suspected contaminated lead to a scrap dealer, and their lead recovery contractor will process the lead through a high temperature purification process (a true lead smelter).

 

 

Quote

Melted out some old wheel weights and had the same problem of purple blue lead with grainy texture.  Stumped any one a asked until recently.   Guys claim it's babbit.   Still not sure if they are right. 

 

That's used horse feed!     Babbitt metal generally will mix well with lead alloys.  Except for high Copper babbitts, it  is pretty good for hardening lead because it's Tin and Antimony, mostly.   But, because there are several babbitt alloys and it's hard to tell which one you have, it's a crap shoot using it.  Sounds to me like you got quite a bit of maintenance-free battery lead in that batch.   Which can be cast, but at higher temps, and watch where you put the dross you skim off.  Will not make accurate rifle bullets.

 

The bottom line - anymore, you CANNOT trust anyone else to know what they are doing when they smelt down "scrap lead or wheelweights."

You have to sort for zinc weights yourself, you have to keep battery lead out, you need to work with small batches that you can afford to scrap if it turns out bad, and if possible, you may want to find someone who can XRay Fluorescence (XRF) test the batches you make, to check for Zn and Ca.   It is no longer as simple as it used to be to make good bullet metal.

 

Good luck, GJ

 

 

 

 

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I've had similar experience. In my case I was mixing old COWW with what I think was babbitt, scrounged from work. Lumpy dross, purple if the heat got too high and nozzle plugging for sure. 

 

At or near the melting point for pure lead, 621°F, I would get "swimmers". IOW, if I stirred in a circular motion to get the melt swirling, little bits of mystery metal would start swimming and collect in the center.

 

Unfortunately I can't tell you what metal caused the problem, however I was able to salvage the alloy. I just kept skimming the dross, while maintaining the 621°F temperature. I did try fluxing with sawdust and kitty litter, with some success. That experience ended my babbitt experimenting.

 

Copper may have been the culprit. If it were zinc, most of what I've read is that it cannot be removed. Blending will just ruin more good alloy. 

 

Access to a Handheld XRF analyzer would be a nice tool, a bit beyond my budget. I just bought some lino, and solder, to blend with COWW. (Sorted to cull any zinc).

 

 

 

 

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Notice I did say "find someone who can XRay Fluorescence (XRF) test" rather than recommending anyone buy an XRF tester.   They run upwards from $10k.

:ph34r:

 

Some of the larger scrap yards May have one, and they May charge a $10 fee to do the test.  Since it's May, now might be a good time to ask around.  :lol:

 

Tin usually oxidizes to give you yellow dross, and it's easily reduced with most wood or oil or wax type fluxes and goes back in the alloy.    The blue dross I've not been able to reduce and have to scoop it off.   My guess is the blue is Zinc oxide. 

 

Good luck, GJ

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I agree it is calcium from battery lead. Had a bunch of this that was supposed to be wheel weight lead. Be careful about any scrap lead you don’t know th source of

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Quote

The blue color is tin that is being oxidized due to the high temperatures.

.....Yes, also tin makes bullets lighter . Dross is gray/black ash - Not a blue color

*** Using this alloy & a high temperature - Do the cast bullets fill out with sharp groove bands & flat bases?

*** Cast at a high temperature are the bullets frosted

 

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▲ due to all the problems with contaminated lead out there I'm pretty much buying processed lead from dealers that I trust.

 

I can get Pb for about $1.30-$1.40 per lb which is worth it to me to skip the smelting process.  Being 73 will do that to you

 

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Tin won't harden a bullet much - takes about 11% Sn in a bullet alloy to raise hardness to about 12 Brinnell.

Zinc will increase bullet hardness very quickly.

Tin is slightly denser than Zinc, so it takes more tin to lighten a bullet density compared to zinc.

 

Good luck, GJ

 

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  • 1 month later...

I tried to melt some "known" alloys in the same pot. 

And it must be contaminated now...Because I keep getting the same problems.

Is there a way to clean a furnace pot?

Just buy a NEW one?

Thanks, smelter Pards,

MG

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It's not hard to clean a steel melting pot.  Follow OLG's steps.   I'll even chuck a small steel rotary brush in a hand drill and scrub dross and dirt off of the pot walls.  For sure, WEAR A DUST MASK if you do!

 

The pot CANNOT absorb zinc or other common lead alloy metals.  The minor amount of "bad" metal sticking to the pot walls won't contaminate a full charge of good alloy, either.  Don't be going magical here.  This is just science.

 

It would be much more likely that your "KNOWN" good metal is not as good as you think it is!   An X-ray florescence test would tell you what metals are in any alloy, and might be worth the $10 or so that testing labs or scrap dealers might charge you.

 

Good luck, GJ

 

 

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No scrapyard in these parts has that testing equipment.

I cleaned it as best as I could by scraping with a blade and also using sandpaper.

The known metal I that tried was 50/50 bar solder (still virgin bar).

I tried sawdust, wax, and even rosin flux.

And I still had the blue crap and hardly any flow through the bottom nozzle.

I'm beginning to think I should either get a new furnace or quit casting.

 

Later,

Mustang

 

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6 hours ago, Mustang Gregg said:

No scrapyard in these parts has that testing equipment.

I cleaned it as best as I could by scraping with a blade and also using sandpaper.

The known metal I that tried was 50/50 bar solder (still virgin bar).

I tried sawdust, wax, and even rosin flux.

And I still had the blue crap and hardly any flow through the bottom nozzle.

I'm beginning to think I should either get a new furnace or quit casting.

 

Later,

Mustang

 

 

 

At what temperature was your mix? 

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Dave, Joe, OLG,

I don't have a working thermometer right now.  I need to get a new one.

I reckon the old one is way beyond calibration.

But I tried setting the heating control rheostat switch in several ranges from just starting to melt the solder clear on up to the top temp setting.

I don't think the mix got any better.

Still is blue and thick.

One of the Pards suggested that maybe I have calcium contamination.

A new smelter (even a Lee 20#) is not in the budget for a spell.

Muchas gracias!

Mustang

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Stinkin' blue+purple gravy!

#!?%*+!!?

 

And I have been very careful to sort out my lead alloy tire weights from the Zn & Fe ones, I thought!

I must've missed some.

 

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All the bottom pour pots that I have used (Lee, Lyman, RCBS) it's easy to remove the pour spout control rod and get to the inside of the spout itself.  Clean the tip of the rod and the inside of the spout - I've used a ball of steel wool tamped down with the control rod and spun with hand drill motor to clean the spout.   Calcium seems to be real bad about building up in the spout.

 

Quote

The known metal I that tried was 50/50 bar solder (still virgin bar).

I tried sawdust, wax, and even rosin flux.

And I still had the blue crap

 

OK, that seems to indicate your pot is running REAL hot.  Bar solder should not give off much dross at all, and it should only be a blue color if the tin in the solder is oxidizing really badly (due to being too hot).   Dial indicator is not making much difference - so the thermostat switch in the control box of the Lee is probably stuck in the ON position.  Whack the box, or take cover off and you might see a snap type  switch that can be replaced (but I never went that far with a Lee pot.....when it stopped working, it went in trash and replaced with a (gulp) RCBS pot.  You probably need to borrow a thermometer from someone else who casts.....just to check things out.

 

Good luck, GJ

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3 hours ago, Mustang Gregg said:

Dave, Joe, OLG,

I don't have a working thermometer right now.  I need to get a new one.

I reckon the old one is way beyond calibration.

But I tried setting the heating control rheostat switch in several ranges from just starting to melt the solder clear on up to the top temp setting.

I don't think the mix got any better.

Still is blue and thick.

One of the Pards suggested that maybe I have calcium contamination.

A new smelter (even a Lee 20#) is not in the budget for a spell.

Muchas gracias!

Mustang

I sure hope this isn't battery lead, you have.

Stop guessing, and get a thermometer:excl:

OLG

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I have had virgin lead and pure lead come out with blueish colors, it is from trace amounts of copper in the lead. If your pot is still not pouring good it is probably from dentrites in the pour spout. From the cast bullet handbook, the chapter on alloys. The dentrites are formed from aluminum and cool just enough in the spout to start plugging it they are easily removed by bending a paper clip, opening the spout with a pan underneath and inserting the clip from the bottom and making a circular motion. Takes all of 15 seconds. If you don't believe it read the book.

kR

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9 hours ago, Garrison Joe, SASS #60708 said:

All the bottom pour pots that I have used (Lee, Lyman, RCBS) it's easy to remove the pour spout control rod and get to the inside of the spout itself.  Clean the tip of the rod and the inside of the spout - I've used a ball of steel wool tamped down with the control rod and spun with hand drill motor to clean the spout.   Calcium seems to be real bad about building up in the spout.

 

 

OK, that seems to indicate your pot is running REAL hot.  Bar solder should not give off much dross at all, and it should only be a blue color if the tin in the solder is oxidizing really badly (due to being too hot).   Dial indicator is not making much difference - so the thermostat switch in the control box of the Lee is probably stuck in the ON position.  Whack the box, or take cover off and you might see a snap type  switch that can be replaced (but I never went that far with a Lee pot.....when it stopped working, it went in trash and replaced with a (gulp) RCBS pot.  You probably need to borrow a thermometer from someone else who casts.....just to check things out.

 

Good luck, GJ

 

+100

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If you have zinc with lead in the pot best thing to do is dump it...purple & blue haze when melting can also show the presence of arsenic, which can show up when melting old reclaimed shotgun shot.

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