Strange problem smelting

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  • Last Post 03 September 2009
amb1935 posted this 27 May 2009

I've been looking at lots of posts on tips for smelting and for bullet casting, but I cannot find anything that addresses my problem.  When I smelt wheel weights, I get a multi-colored crust on top of the lead.  I flux multiple times, but the colors keep coming back.  They start off as a light, pale yellowish-brown, and eventually (if left alone) will turn purple and blue.  What is this stuff?  I guessed at first that this was some motor oil or some contaminant on the WWs, but no matter how much I flux, it keeps coming back.  Any thoughts?  Thanks! -Aaron

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RicinYakima posted this 27 May 2009

Aaron,

My first guess is that the yellowish stuff is tin oxide and the purple is lead oxide caused from over heating the alloy and then exposure to air.

What does your thermometer say the temperature is?

Ric

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jhalcott posted this 27 May 2009

Ric , MY thermometer doesn't SAY any thing. I've got to READ it! When I smelt OR make alloy ingots ,I use a large, deep, open frying pan. It holds about 55 pounds of molten metal. I flux a couple times and haven't seen this “crust” AAron speaks of yet. I do use a thermometer when I smelt AND cast. I try to keep the melt temp under 850 degrees. Zinc ww's will float a bit before ruining the alloy.

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runfiverun posted this 27 May 2009

ric has it nailed. turn down the heat.

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RicinYakima posted this 27 May 2009

I can't think of any good reason why you would need more than 700 degrees. WW's are in the total liquid stage at 540 degrees, plus 100 seems like enough. All of my smelting experience has been with a 50 pound cast iron plumbers crucible fired with propane, so I don't know the issues with your frying pan. It isn't aluminum or teflon coated is it?

Ric

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jake mdw posted this 27 May 2009

after smelting literaly a ton of wheel weights into ingots and bullets,I know the problem your talking about. the cause is definately tooo much heat. a couple of times i have left the pot to warm up a little too long and had the same results .by the way,the colors are realy intense and great looking, but can actualy be sign that you have ruined the alloy by causing some metals to rise and be skimmed off as dross

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JetMech posted this 28 May 2009

runfiverun wrote: ric has it nailed. turn down the heat.Ditto. Cast some pure lead a couple months back and most of the way thru a 100# pot, I got that blue sheen. Checked the temp and it had climbed from the 750 I was at to almost 900!

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CB posted this 28 May 2009

Yep too much heat. The yellow is usually oxidation combined with dirt and other crud. Turn the heat down and you will be fine.

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jhalcott posted this 28 May 2009

I usually start removing the dross and floaters at 700 degrees. By the time i've got a few trays of ingots poured, the temp has risen some. Their is no real issue with the pan,my turkey fryer does have a slow to respond gas valve though.! When I make a batch of alloy,I keep the heat as cool as possible. Just enough to melt ALL the ingredients. This heat rarely exceeds 650 degrees.

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KenK posted this 28 May 2009

My propane burner has two speeds, hot and hotter.

I scoop the clips out as soon as possible; give it one quick flux and start pouring ingots.  I can do a full five gallon bucket in two hours, with a 3 quart pot.

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amb1935 posted this 28 May 2009

I don't have a thermometer that can handle this type of heat. I did try heating up the wheel weights much more slowly, and that worked well. I started turning down the temp and fluxing immediately as soon as the lead surface started turning a little yellow, and that definitely helped. I figured it was either the tin coming out of solution or the lead oxidizing. Problem solved, thanks a lot! The only problem I have now is junk caking up on my spoon that I use to remove the dross. I think it is a mixture of dirt and beeswax, but it won't melt off very easily. I tried cleaning with acetone, but no dice. Anybody got and ideas? I'm pretty sure it's a stainless steel spoon.

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RicinYakima posted this 28 May 2009

The coating on your spoon is most likely all the things you mention plus the oxides that you can not reduce back into your alloy. When you are done for the day, set your spoon in a cup of water overnight. Most of the things that sticking are water soluable. Then I let it dry in the sun and brush it with acetone and a brass brush. Just remember that this dust is 100% more toxic than anything else about casting bullets. HTH, Ric

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amb1935 posted this 28 May 2009

RicinYakima wrote: Just remember that this dust is 100% more toxic than anything else about casting bullets. HTH, Ric Thanks Ric.  That's really good to know.  No sense in taking unnecessary risks.

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n5638b posted this 03 September 2009

Hi All, New to the forum as well as casting. Found this thread from searching because I've had the same problem with too much heat.

My question is this, now that I've scraped off all the yellow, fluffy crud off the top, is the lead still usable? Can it be used for muzzleloader bullets?

Thanks!

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canalupo posted this 03 September 2009

n5

I don't know your alloy is but wheel weights are about 3 to 5% tin.

Pure lead is better for round balls. For Mini's, wheel weights are probably OK. You may have to add some pure lead to get a softer bullet for the conicals.

Once you skim off the slag, you will get most of the oxides too. If your mix starts to get a rainbow sheen you are running too hot.

It is still usable once you clean out the slag.

hope this helps good luck.

Bob D

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JetMech posted this 03 September 2009

What did you originally melt? Oh, and Welcome!

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runfiverun posted this 03 September 2009

what did you start with as an alloy? ww's are about 1/2% tin and 3-4% antimony. fluffy stuff is plain ole dirt it is pretty dang hard to remove stuff from an alloy just by getting it hot or letting it sit but oxides will come out if for a muzzle loader the softer the alloy the easier it is to cram it down the bbl. or if using a harder alloy it has to be a very good fit to your rifle.

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n5638b posted this 03 September 2009

Sorry guys, should have mentioned the mix. I'm using wheel weights with some 60/40 solder mixed in.  Hoping to end up with a mix of about 91% lead, 5% tin, 4% antimony.

Of course I'm mixing it up by weight and I'm assuming the ww's start at 95.5%, .5% and 4%...

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