Get the [zinc?] out.

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Thornapple

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I've been casting about a year, have cast maybe a hundred pounds' worth of ingots from wheel weights, using a Lee electric bottom-pour furnace. Today I was really on a roll, filling the little pot and emptying it 3/4 into the ingot mold and refilling again. I turned the temp up from my usual of about 6.5 to about 7.5 (the dial runs from 2 to 9), in hopes of filling the ingot mold a little cleaner without having to heat it up before casting after each refill of the pot. At this point I have to admit that I haven't known what temperatures relate to what settings - but an IR thermometer later seems to tell me that 6.5 is meant to be target of 650degreesF.

After I refilled the pot (now set to 7.5) with WWs and gave it some time to reheat, I came back to find the clips all tangled up with some sludgy strange-textured ...sludge, on the top of the pot. It was lead-colored but the texture was all wrong. I spent a half hour fluxing with pine shavings and paraffin, finally pulled a few pounds' worth of the sludge off the top including what came off with the WWs.

I found something in this thread (#post-7741802) about zinc in the melt, and it fits that I appear to have turned the temp up past zinc's melting temperature and failed to winnow my WWs properly. OK, so I brought the temperature back down in a couple of stages, fluxing as I went, to the dial setting it had been at before (6.5) which seemed to get me a surface temperature of as high as about 675F. There was no longer a thick sludge on the top and it had stopped going purple (I did learn at least one thing today - purple means it's too hot), but the surface texture was still just all wrong.

I was expecting that as I brought the temperature down below zinc's melting point, the zinc would precipitate somehow and I'd be able to pull some sort of chunks of it off the top, maybe mixed with the fluxing ash, but I just spent about 15 minutes pulling my favorite soup spoon across the top and finding that the whole surface of the melt had just gotten Sticky, for lack of a better word. The melt isn't rolling off the hot spoon like it should; There's a sortof membrane that's sticking to the the spoon (yes, it was plenty hot) and sticking to the sides of the pot above the "waterline." I dropped a couple of cold ingots in, to help drop the temp to the usual 6.5 level. I didn't see much if any improvement in 15 minutes of stirring and fluxing.

I have unplugged and walked away and I have questions:
  1. When I reheat the pot, will I be able to pour clean lead-alloy ingots out of the bottom?
  2. Will I be able to get this sticky crap off, as in will it separate from the lead?
  3. Should I have kept stirring and fluxing?
  4. Do I need to heat this pot up really hot and just dump the whole mess into trash-bound ingots and start over?


Appreciate any help or advice!
 
ah... so I'm coming to understand that accidentally contaminating one's lead with zinc is A Thing... ok, well then I feel less embarassed about it, I guess. Thank you!
I'm not sure I'm game to try messing with 600+ degrees molten metal and sulfuric acid gasses.
 
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Thornapple said:
ah... so I'm coming to understand that accidentally contaminating one's lead with zinc is A Thing... ok, well then I feel less embarassed about it, I guess. Thank you!
I'm not sure I'm game to try messing with 600+ degrees molten metal and sulfuric acid gasses!
Click to expand...

You weren't the first and won't be the last.
 
The numbers on a Lee pot don't mean anything. Also using an IR thermometer to guess liquid lead temps is not very accurate. Those devices work best on a dark surface.

Another thing, using your casting pot to break down wheel weights or other sources of lead is not ideal. You just found out way.
 
Texas10mm said:
Another thing, using your casting pot to break down wheel weights or other sources of lead is not ideal. You just found out way.
Click to expand...
Hahaha yep. I've actually thought often of the old man at my favorite gun shop who told me I should have one for casting and one for melting, and thought as often that I don't really seem to need a second one.... yeah. Most times old guys say stuff, there's a reason. And generally even before I get to be as old as they were, but at least by that time, I've recognized what it was. It was because Zinc. Though also while that bottom spout fills a half dozen .45s just fine, it takes an almost painfully long time to fill 4 ingot molds.

Texas10MM: Are there inexpensive reliable solutions for determining actual temperature of molten lead alloy?
 
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If you lower the melt temp below zinc's melting point, the zinc will come out of solution. . . but you'll have lost interest and wandered off. It's really slow, like days. Also, all of the alloys that make WW desirable vs pure lead would separate first.

You've discovered why we sort WW.
 
Yep, you're not alone on that faux pas. You may be able to remelt the questionable alloy and get clean lead out of the bottom, but I would try a lower temp, just enough that the lead is pouring. What is there to lose? You may be able to salvage some good alloy from the mess...

Hint; don't smelt in your bottom pour pot. The design of the valves makes it very easy to produce a drip from a tiny piece of dirt, sand, carbon, etc., so I suggest you smelt/mix alloys in a separate pot. I use either a stainless sauce pan or cast iron pot on a Coleman stove so my bottom pour only gets clean alloy...
 
A few years ago I tried using wheel weights. After each casting session I empty the pot as most do. After a month or so I found the bottom of my Lyman Mag 20 had an inch or so of a grayish coating lining the bottom and sides. It took a screw driver and a little work to break it free and remove. That and the chore of washing the wheel weight in kerosene, separating out iron clips and debris just wasn’t worth it. The stink of the rubber dust burning off wasn’t pleasant. Had I not another source of lead, my gun clubs back stop, I may have stayed with it.
Just saying in my case just not worth the hassle.
 
Most of the above posters have about covered things. I would have said everything Texas 10MM said except that he posted first.

I have been casting with wheel weights for a long time and I have good results with them. Now days I hand sort them. There is a lot of info out there about this so I won't bore everyone by repeating it. Also, if you plan to use wheel weights you should get another pot for making ingots and keep the raw dirty stuff out of your casting pot. A cut off propane tank or a Harbor Freight Dutch oven makes a decent melting pot using a Turkey fryer burner as a heat source. A casting thermometer is nice to have too!

The Cast Boolits site has several stickies about wheel weights that are worth reading. A couple cover XFR analysis and another covers sorting weights.
 
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It is possible to treat the melted alloy with sulfur by converting it to zinc sulfide, but it’s hardly worth the bother. Just dump it and start again. Maybe you can make fishing sinkers with it.
 
Please excuse the thread drift , one question and I am outta here.
A guy from the Washington coast gave me a bucket of pyramid shaped fish net weights. What are chances they even have any lead in them?
 
I’ve done that. I know they aren’t pure lead, just hope they ain’t pure zinc.☹️
 
Thornapple said:
Texas10MM: Are there inexpensive reliable solutions for determining actual temperature of molten lead alloy?
Click to expand...
The RCBS thermometer is about $50 and is money well spent.

https://www.rcbs.com/accessories/specialty-items/16-81175.html

For smelting wheel weights, I've used a propane deep fryer with a cast iron pot. DO NOT USE AN ALUMINUM POT. You will very quickly have 200 pounds of molten lead all over the ground if you do.

Buy a cheap stainless steel strainer to get the clips out and use a steel ladel to scoop out the lead into the mold.
 
the last five gal bucket of wheel weights i got only about 1/4 of the weights were lead. the rest were zinc or steel. i take a dike and cut into all weights. zinc and steel you can not cut or cut easy. lead wheel weights you can cut a line with ease. it is best to check your wheel weights before throwing them into the pot.
 
Thornapple said:
ah... so I'm coming to understand that accidentally contaminating one's lead with zinc is A Thing... ok, well then I feel less embarassed about it, I guess. Thank you!
I'm not sure I'm game to try messing with 600+ degrees molten metal and sulfuric acid gasses.
Click to expand...
Zinc doesn't pour very good bullets and they just look like crap and can't seem to fix or figure it out until you realize you have some zinc in it. Probably best to just pour in a pan and sell it back to the recycling center.

BUT make sure you have that problem first.

In my own Lee furnaces I've NEVER had zinc get hot enough to melt before I noticed it in there while fluxing. Even after a LONG time, EVEN after the lead was super hot because I turned it up and forgot to add enough, then I tossed in some wheel weights to bring it up to the brim... the lead melted near instantly and the zinc and clips floated there looking brand new and bobbing on the surface like cork fishing bobbers. Skimmed them off the top and they looked like brand new no melting at all.

There are other contaminants in all the crap that comes in a bucket of wheel weights that came make sludgy looking junk. Adjust the temp on the furnace to where you normally pour and spend the cooling down time to flux it good, this will also speed up the cooling off.

Now pour and ingot in a real ingot mold. Let it cool good and look that over close. If the mold filled out good and all the corners look clear and sharp, no porosity. I'd bet there is no zinc in it. Try pouring some bullets. If they start looking good as the mold heats up then I'd just start pouring and keep that pot full separate from every thing else for close inspection and weigh a few. If you can't find A LOT of problems with that run and start to wonder what the problem is with a little zinc, then there is no zinc in there. If it DOES have zinc in it you will get fed up with trying to pour them pretty quick, long before you have emptied that pot.

Another thing you can do is set an old bullet you've cast before and know is lead and a piece of suspicious material next to each other and hit 'em both at once with the torch, the lead will melt LONG before the zinc has any change at all. It is obvious.
 
frankmako said:
the last five gal bucket of wheel weights i got only about 1/4 of the weights were lead. the rest were zinc or steel. i take a dike and cut into all weights. zinc and steel you can not cut or cut easy. lead wheel weights you can cut a line with ease. it is best to check your wheel weights before throwing them into the pot.
Click to expand...
Why not just drop them on the floor and listen to see if they *Tink*?

When I first got into casting, I heard the advice, "If it *Tinks* it's Zinc." Lead wheel weights are very dead sounding when they hit the ground. Zinc and steel have a very metal *Tink* when they hit the ground.
 
you could drop them but my hearing is not that good and sometimes they don't tink. you got to pick them up anyway so for me it is easy to nip them with the dikes and i don't have to bend over to pick them back up.
 
Iggy said:
Please excuse the thread drift , one question and I am outta here.
A guy from the Washington coast gave me a bucket of pyramid shaped fish net weights. What are chances they even have any lead in them?
Click to expand...

If they are commercial weights they are most likely pure lead. If home cast your guess is as good as mine.

One quick tip. Weigh them. If the weight is very close to what it should be they are lead.
 
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