bad issues while smelting lead and need help

[latesvak]

so im melting down a 5g bucket worth of ww like i have done so many other times . im cooking them down in a c.i. dutch oven (6" tall and 14"wide) over a turkey burner . not my first rodeo doing this by any means . so the first two melts went fine with me getting 12 1.5 lb ingots per pot . previously i had sorted and pulled all but the lead ww vs others. if i think it might not be lead i scratch it on a file to rough it up or i will dent check it with some pliers just to double check. so im pretty sure all the bad ones are out .
well after getting this 3rd pot melted down and getting ready to start skimming the dross off it just looked a bit off to me . then after getting all the clips out i skimmed it off and added some wax then waited for it to burn off then scrape all the sides and bottom as usual. then it got an almost iridescent color to it . like some purple/orange/yellow layer on top. wth is this im thinking? so i skim it off and fluxed again. i tried 2 different waxes and sawdust and this layer of junk kept coming back . any help would be greatly appreciated .

thanks

latesvak

 

[grubbylabs]

If you don't get a response here look here at this site.

Casting bullets is what they do.

 

[Trent]

You sure you didn't get Zinc mixed in to it?

 

[res45]

Sounds like you just got your alloy a little overheated,lead/Tin when overheated will form a purple/blue/gold colored dross. The color is caused by oxidation and the difference in the thickness of the oxidized layer will determine the colors. You can't flux those colors out it just the nature of the lead an pure lead to nearly pure lead will form those colors. You might even see streaks of those colors in you ingots after there poured and hardened.

If you get zinc in your ingot pot you will be looking at something with the consistency of oatmeal. Lead melts at roughly 622 degrees while zinc melts at around 788 degrees if you keep you ingot pot at around 650 degrees or slightly lower the zinc weights will float to the top before they can melt and you can just skim them off.

 

[grubbylabs]

Its probably punishment for using a good piece of cast Iron. I have yet to see a cast oven or pan that could not be saved until some one like you puts lead in it.

 

[rcmodel]

I agree it got too hot.

The iridescent sheen is indicative of over-heating lead or lead alloy.

Count your blessings!
Had you been using the turkey cooker for it's intend purpose?
You would be eating thanksgiving dinner at McDonald's Thursday instead of turkey at home.

rc

 

[cberge8]

Yup, sounds like you over heated the melt. Slowly lower the temp, fluxing occasionally, once the temp gets low enough that stuff will flux right back in.

 

[drsfmd]

Sounds like you just got your alloy a little overheated,lead/Tin when overheated will form a purple/blue/gold colored dross.

+1. This is almost certainly what you were seeing. Turn the heat down a little and I bet it goes away.

 

[latesvak]

thanks for the heat answers . that seemed to help and all went smooth after that and as for the ruining a good cast iron pot (which would be just wrong) i would have to agree with you but it just so happens that this pot originally had 3 2.5" tall legs and one had broken off so im sort of thinking i gave it a rebirth of sorts. thanks to all for the answers given.


latesvak