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Lead Melting Question

Discussion in 'Uncategorized Threads' started by straycat, Aug 21, 2008.

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  1. straycat

    straycat TS Member

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    The last couple times I melted wheel weights I kept getting a rainbow colored film on to of the lead. It would skim off but then would form right back.A friend told me today he had the same problem with his last batch of weights and when he tried to run it through his shotmaker it would throw big gobs of lead frequently. Has anyone else experianced this? If so is there a way to get rid of the film?Or is there something you can add to this to get rid of it? Any ideas?

    Thanks,Joel
     
  2. phirel

    phirel TS Member

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    Joel- I can't give you a direct answer to your specific problem but can give you some general thoughts. You seem to have some sort of contaminate floating on top of your melted lead. The thin film of contaminate is refracting the light.

    When I melted lead, I used a large container but then transfered the melted lead into a smaller electric furnace designed for bullet molds. This furnace dispensed the lead from the bottom and kept out any contaminate floating on the surface.

    One good way I did find to remove surface contaminants was to use a little sawdust on the top of the melted lead. This charred and absorbed a lot of stuff and it is easily skimmed off.

    Pat Ireland
     
  3. boonedoggle

    boonedoggle TS Member

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    i'm old enough to remember the plumbers on my dad's job sites using melted lead. the little rainbow effect was there then, still is. it's simply oxidation of the lead and minor other stuff. forget about it. you're just going to spit the stuff out and leave in the dirt at the end of the range anyway.
     
  4. vdt

    vdt Active Member

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    try some bees wax and put a small amount in and slowly stur it. it will remove impurities
     
  5. Quack Shot

    Quack Shot Active Member

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    Fluxing and removing the dross is a good idea. Heating the mix too high will allow the antimony to separate and lay on the top, so you would be removing the good stuff if it's too hot. The rainbow film is just oxidation, unless there is some other impurity I've not come across. As to the problem with dropping the mix, it could be that you have some Zinc or other compound in the mix. There are some new wheelweights that are made from zinc and they take a lot of heat to melt. If there are a few that float up and don't melt right away, remove them, The tape-on weights also seem to be a problem. I didn't use them anymore and set them aside for casting sinkers. A good thermometer (Pyrometer) will help keep your mix at the right temps. I now have an infrared thermometer as well as my immersion type Pyrometers. I just don't play with lead anymore.
     
  6. Haskins Bill

    Haskins Bill TS Member

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    doggai,vdt, and Quack Shot are absolutely correct it sounds like you are melting at too high of a temperatue and wasting the antimony that gives your shot the hardness you want. Use the bees wax/ toilet bowl seal or a commercial flux to clean out impurities. It only takes a small amount of beeswax or even parrifin and it will smoke and flame. Stir it in and watch the bad come to the top. I have been told that the Zinc wheel weights will sort of dissolve much like a throat lozenge will if you let them sit in the melt for too long. Go to the site http://wwwtheantimonyman.com and find more info. He says below 600 for lead as zinc melts at 787. Bill
     
  7. ricks1

    ricks1 TS Member

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    the blue color is from the pure lead are you mixing the stick on's in the mix? rick
     
  8. phirel

    phirel TS Member

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    Some excellent advice about temperature, but I have to question the comments about oxidation. Lead oxide is white. The rainbow seen on the surface of the melted lead is clearly due to refracted light.

    Pat Ireland
     
  9. Sitsinhedges

    Sitsinhedges TS Member

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    That's great, any more of this kind of stuff knocking around?

    Cheers
    Andy
     
  10. Brian in Oregon

    Brian in Oregon Well-Known Member

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    Keep in mind that some of the alloys can be poisonous if overheated and put into the atmosphere. Turn the heat down, or get a filter mask cartridge for radon daughters. It will have small enough filter media to block these metals.
     
  11. winchesterm12

    winchesterm12 TS Member

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    Hey, in some parts us plunbers still pour lead joints
     
  12. plinker61

    plinker61 TS Member

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    i pull out all the stick on wheel weights and the problem went away,another thing to look at is if the weight is marked fe its zink,also honda ww are zink.sort before melting,mark
     
  13. Shootrman

    Shootrman Member

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    I believe Pat Ireland hit the most important way of removing impurities. Tap you molten lead from the bottom and scim the impurities from the top. My two cents: The rainbow colors are also caused by high heat and the presence of BABBIT. I have been making shot for a number of years now and found that when I recieve wheel weights originating from trucking or bus companies I have problems with the ingots I make. I also have a source coming from and industrial site and again I run into BABBIT. I personnaly cant tell the difference and haven't found anyone that can. If anyone out there knows the secret please inform me. After scimming off most of your impurities and just before you pour your ingots them I would suggest putting in the wax and letting it burn off. I use about a 3 inch square about a 1/2 inch thick. Again, only my 2 cents
     
  14. Quack Shot

    Quack Shot Active Member

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    Pat Ireland,

    Is "Lead Oxide" really always white? Let's explore this a little further. Have you ever seen or heard of something called Minium? (red lead or lead oxide) It's certainly not white! I thought that "White Lead" was Lead Carbonate and not Lead Oxide. Maybe I'm wrong?

    http://www.galleries.com/minerals/oxides/minium/minium.htm

    How about Massicot? (lead oxide, lead monoxide)

    http://www.galleries.com/minerals/oxides/massicot/massicot.htm

    There are more examples to be found if one were to explore.

    Even though some Oxidized Lead "might" be white in color, what does it look like when it first begins the oxidation process on the surface of molten lead at high temperatures? If you eventually have enough of it, you may see what you described if it is truly white in color as you claim. What does Silver Oxidation look like when it begins? Silver Oxide is usually black. At the beginning the Silver is "Tarnished" or dulled. It is still mostly Silver, but dull, or gray in color. When the oxidation process continues long enough, you may have enough of it to look black.

    Now, could you please explain how "refraction" works in this case? I'd be interested to understand this.
     
  15. phirel

    phirel TS Member

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    Quack Shot- Thanks for the information, you went into more detail than I did. My observation that lead oxide is white is based on the fact that lead oxide was once widely used as the exclusive white pigment for paint. The stuff is white. Lead carbonate, that forms on shot in the ground is also yellowish-white.

    The rainbow colors seen on some molten lead surfaces is reflected sunlight that has been refracted in exactly the same manner as moisture in the air refracts sunlight to make a rainbow. The different wavelengths are bent at different angles and reflected as a spectrum. A thin skim of oil on the surface of water will do the same thing.

    plinker61 noted above that the zinc wheel weights are marked Fe. This really has me confused.

    Pat Ireland
     
  16. Haskins Bill

    Haskins Bill TS Member

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    I think the zinc wheel weights have Zn on them. Can't be TOO positive but the ones that were zinc on them when Chrylser went to all zinc weights at Toledo a few years back were marked such. Now then, when the new Wrangler came out it used a mix of zinc and lead for domestics but only zinc for exports. Tires are mounted and balanced by a vendor and they have the capability of segregating tires for export and domestic. It will be a moot question as all lead based wheel weights are banned starting I believe this year or next. Bill
     
  17. Quack Shot

    Quack Shot Active Member

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    Zinc = Zn and Iron = Fe. There are Iron or steel wheel weights out there as well and they would probably be marked "Fe". A lot of the Zinc weights are not pure Zinc. They are usually a Zinc Alloy, of which the exact content could be anyones guess. I would expect it to be Zinc, Aluminum, and Copper, but I don't make them and don't know for sure. If you get the Fe marked ones to melt, you've probably used an awful lot of heat!

    Pat

    I always thought "refraction" referred to light passing through, from one mnedium to another. This would "bend" the light allowing dispersion of the different frequencies through the medium, giving the "rainbow effect". The light does not appear to pass through the lead, but is "reflected" off of the surface instesd, in an irregular pattern. It appears that there is some chromatic dispersion occuring, but is it really due to "refraction"? Just curious.
     
  18. BAP

    BAP TS Member

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    I'm new to lead and melting it and pouring into ingots. I recently poured 3 dozen into a muffin tin but they stuck so badly I had to destroy the tins to get them out. What do I need to do different? Is there a good release agent or do I need to cool them fairly quickly to keep them from sticking? Bill
     
  19. Sitsinhedges

    Sitsinhedges TS Member

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    I had the same problem and solved it by dusting them with a bit of french chalk.

    Hope that helps
    Andy
     
  20. phirel

    phirel TS Member

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    Quack Shot- I believe it is refraction. Immediately above the reflective surface of the lead is a thin layer of several gases. The reflected light passes through these gases into air resulting in refraction. I know of no other way that light can be dispersed into a spectrum. If my model is incorrect, I would appreciate learning something new.

    Pat Ireland
     
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