Zinc contamination with stick on wheelweights

[RogerWatsonfromIdaho]

I know about clip on zinc wheelweights, but I did not know about stick on zinc wheelweights. Somehow it never occurred to me. It should have.
I have been separating and saving my stick on wheelweights for 3 years and I had about 10 gallons of them. I do not have a muzzle loading firearm so I did not have a use for them until I decided to try a 50/50 mix of stick on wheelweights and clip on wheelweights. So I started melting my stick on wheelweights into ingots. My mistake was using two propane torches to melt the stick on wheelweights faster. I must have melted some zinc stick on wheelweights. I got all the signs of zinc contamination, but I did not recognize it because I had never had it occur previously. There was a mushy metal floating on the melted lead alloy. It was impossible to flux the alloy properly. When pouring metal out of the dipper onto the surface of the lead, it turned frothy. Bullets did not fill out well. When the lead level got low, the alloy turned purple. The most frustrating part was the spout freeze even at 850 degrees F. I would unclog the spout by heading it with a propane torch. That worked, but even better was to put a drill bit (held by vice grips) up the spout and turn it slightly. This always worked, but I could not keep the spout from clogging. Finally I realized what was going wrong. I decided to throw away the 40 pounds of zinc contaminated lead alloy. The bullet moulds cleaned normally. I cleaned out the electric furnace. There was a glob of metal on the end of the rod which closes off the bottom pour spout. I pulled that off with pliers. Now I know to set the electric furnace on 700 degrees F. and do NOT use the propane torches. I posted a photo of the zinc stick on wheelweights. All the weights in the bottom row have "Zn" in the upper right hand corner. The other weights do not. Yes I checked all of them with a magnetic and these are not magnetic. I can sort out the magnetic and zinc wheelweights before melting, but with the furnace set on 700 degrees F. and not using a propane torch, I do not have to worry about making a mistake.

[grumpy one]

I think you may be underestimating the zinc hazard, though it is more troublesome with clip-ons than stick-ons. I find lots of unmarked zinc WW, both stick-on and clip-on, and I have melted some into pots of WW without the pot temperature appearing to go above about 720*F. Because zinc will alloy with lead, and the melting temperature of the alloy is below the melting point of zinc, dissolution (rather than melting) can be a problem. I've lost a couple of pots of WW that way recently.

I've only had the problem occur at 720-730*F, rather than 700*F, but if I were you I'd be reluctant to trust my thermostat that precisely. Furthermore I think zinc will disslove into lead at 700*F, it will just be a slower process than at higher temperatures.

Be afraid - be very afraid.

[RogerWatsonfromIdaho]

Years ago I tested if clip on zinc wheelweights will melt in my RCBS pro-melt with the thermostat set at 700 degrees F.
I tested:
1. let the zinc wheelweight rest on the surface of the lead for 10 seconds.
2. Use the dipper to hold the zinc wheelweight under the surface of the lead for 10 seconds.
3. Put in another batch of clip on wheelweights, melt them, cast into ingots and still the same zinc wheelweight had not melted.

Recently I tested if stick on wheelweights would melt using #1 and 2, but not 3.
I will give it a test. So far the 700 degrees F. setting is working.

[DLCTEX]

If you could retrieve the contaminated alloy, I would like to have it. I have reclaimed contaminated lead by reducing the heat slowly and skimming off the mush that forms on top. This doesn"t remove all of the zinc, but removes enough to cast perfectly good boolits for my uses. I have tested the boolits for maleability by hammering them on an anvil and firing them into various mediums and can not detect any difference from pure WW. It produces a boolit that looks like Silver.

[grumpy one]

My "test" (really accident rather than test) had the wheelweights heating unattended for half an hour, with nearly all of them already melted at the beginning of that period and the pot temperature initially at regular WW melting point of something under 600*F over a Coleman stove. When I returned the temperature had climbed to 720*F and the zincers had already dissolved. Hence it may take up to half an hour of immersion for dissolution to occur.

Most (not all) zinc stick-ons are painted, and the paint may retard the dissolution process. I don't know whether whatever did the damage to my pot-full was a clip-on or a stick-on. The very next time I smelted WW, the same thing happened again. Since then I've been much more attentive to what I put in the pot. I bend the suspect weights in the vise (look how culturally sensitive I am - I just used an American spelling!) Zincers are very difficult to deform and seem to snap rather than bend.

[grumpy one]

Dale, I've skimmed and cooled and remelted and skimmed some more. In the end I got to where the residue (I'd scraped off about 70% by then) looked like proper WW, but when I poured it into ingots the radius on the top edge was larger than normal. Since then I just toss the whole pot straight into the skip rather than waste time. I did keep a couple of ingots (marked "Contaminated") to use to warm up my impact test rig.

[Old Ironsights]

Contaminated alloy poured into catfood/tuna cans makes great doorstops...

That's why I take the time to hand sort each bucket of WWs into Big, Small, Stickon and Crap.

[AZ-Stew]

I bend the suspect weights in the vise (look how culturally sensitive I am - I just used an American spelling!) Zincers are very difficult to deform and seem to snap rather than bend.

There's the best clue! A 12 year old school girl can bend a strip of pure lead stick on WWs with her hands, but the "zincers" (culturally sensitive spelling) are hard as a rock. I have a hard time bending the thinnest of them without resorting to tools.

Regards,

Stew

[shotman]

In the past [last year] I have gotten a few good deals on ebay[not anymore] but 2 of those adds of-- PURE WW -- were true but they were not pure lead alloy WW. they had zinc in the mix. I found that if you melt the ingots in the cast furnace and dont try fluxing right away the zinc will tend to float if you dont let temp get to high. I dont have any problem with boolits but making shot is a whole other game.

[Leadforbrains]

Hey Roger I have a question. What has lead ( no pun intended) you to believe that the unmarked ones are zinc? The reason I am asking is that I have some of the unmarked ones in my possession that are similar in appearance to your unmarked ones in the photo. I have already sorted through my stickons and thrown out all tne ones that are marked zn.
Thanks in advance for any additional info.
steve

[RogerWatsonfromIdaho]

LeadforBrains,
The lead stick on wheelweights are easily scratched with a thumb nail. The zinc stick on wheelweights cannot be scratched with a thumb nail. The zinc wheelweights are much more difficult to bend. Try dropping wheelweights on a concrete floor. The zinc will give a slight ringing sound, the lead will not. The zinc stick on wheelweights are look shiny and the lead stick on wheelweights are look dull. Try breaking open a zinc wheelweight and putting a drop of muratic acid on the exposed part. If zinc it will quickly form large bubbles of hydrogen. No smoking please. Also zinc wheelweights will not melt in my furnace (RCBS pro-melt) when the thermostat is set on 700 degrees F. True I did not test the wheelweights in the photo with all these tests. Most of the time I can tell by appearance of the wheelweights. If I make a mistake the electric furnace will not melt the magnetic or zinc wheelweights when set at 700 degrees F.

[Leadforbrains]

Hey Roger thanks again for the info. I have been fortunate so far. No zinc contamination as of yet. Informative threads like yours has helped me quite alot.
Thanks again,
Steve

[EchoSixMike]

I'm thinking the easiest way to sort out the zinc WW's will be chemically.

5gal pails seem to be the easiest, fill with water until amost covers all WW's then pour in a bottle of muriatic acid (which is hydrochloric acid). Let work for a few hours(outside obviously), this will generate hydrogen gas. After it's worked for a few hours, pour in a few boxes of baking soda to neutralize the acid and then drain. HCl + NaCO2= CO2+H2O+NaCl(salt) so no big deal as far as nasty chemicals go. Zinc chloride is a useful flux and is not particularly toxic either. Zinc WW's will be dramatically corroded and black in color, lead WW shoud be pretty much inert lead color with corroded clips and any steel clips.

Allow WW's to dry prior to smelting, or heat from top with burner.

People use muriatic acid to clean their drive ways, so I doubt there will be any huge enviro issue unless you have neighbors out to get you. S/F....Ken M

[grumpy one]

Quite a lot of zinc WW are painted. I'm not sure the HCl will cut through the paint coating - may depend on what kind of paint it is.

[copdills]

I have always used a thermometer and never go over 700 degree's when I am smelting and never had a problem pulling out the zinc that didn't melt, zinc melts at 787 degrees , ww's at 521 and pb at 621

[randyrat]

There is one more method that is 100% but slow. Use a hand held wire cutter and snip an edge of each one. Zink or iron WW you won't be able to score, lead WWs you'll be able to score. It's real slow but 100%. I just watch the melt and stir a little to spread the heat out evenly and scoup out zink turds and steal. My last batch of 800 lbs i pulled about a dozen zink and some steal.

[Chunky Monkey]

There is one more method that is 100% but slow. Use a hand held wire cutter and snip an edge of each one. Zink or iron WW you won't be able to score, lead WWs you'll be able to score. It's real slow but 100%. I just watch the melt and stir a little to spread the heat out evenly and scoup out zink turds and steal. My last batch of 800 lbs i pulled about a dozen zink and some steal.

I use this method as well as the drop test and haven't had a problem yet!

[Blackhawk Convertable]

You can sell the zinc ones to the salvage yard rather than throw them away. Might as well get a little money back for them, you know....

[mikenbarb]

Do a forum search for cannon balls because some guys here buy them to make zinc cannon balls with.
What I do with my ones in question is scratch them on my concrete patio. If it scratches its zinc and lead just leaves a streak.

[TexRebel]

keep your smelter below 700 deg and the zinc ww float to the top, if you do melts some zinc it to your mix , as long as it is less than 5 % you will not have a problem, some of the older loads called for 5 % zinc in the lead to make it hard, it just needs to be cast hotter