View Full Version : Molten lead color
webby4x4
05-04-2009, 03:42 PM
Hi all - I was doing some casting this weekend and noticed that I couldn't quite keep the color of the molten lead a shiney silver color (like quicksilver / mercury).
Instead, it was more of a gold color, with a thin skin on the top.
I fluxed 5 or 6 times, but it would keep doing that within a few minutes of me fluxing the lead. I also turned the temperature down too, but it didn't seem to make much difference.
The mix started as pure lead and I added 95/5 (tin / antinomy respectively) fluxless solder to the mix.
I should have taken a picture (I will next time), but was curious if anyone knows what would cause the lead to form a thin skin of gold "scum" on the top.
P.S. The boolits cast perfectly (nice a clean, sharp edges, good fillout, etc.) and the lead is also very clean.
thanks,
Rick
sheepdog
05-04-2009, 03:53 PM
I get this alot too. Not sure if its high tin content or too hot but I see it alot. Most of all when I got the ol Lee 10 pounder rolling at 8.5 trying to get a tough mould to fill out.
webby4x4
05-04-2009, 04:47 PM
I get this alot too. Not sure if its high tin content or too hot but I see it alot. Most of all when I got the ol Lee 10 pounder rolling at 8.5 trying to get a tough mould to fill out.
I'm running the same pot and typically set it around 8.5 myself.
I tried turning it down to about 6.5, but I started to get some folding in the boolits, so I ran it up to about 7.5 and that was about the minimum temp I could go with - didn't seem to make a difference.
runfiverun
05-04-2009, 09:56 PM
gold is a good indicator of tin.
pure lead will usually show a blue/purple color.
put a heat barrier on top of your mix it will also help keep the oxides down and the temp more consistant.
Bret4207
05-05-2009, 07:08 AM
It's the heated tin oxides.
jdgabbard
05-05-2009, 10:31 AM
gold is a good indicator of tin.
pure lead will usually show a blue/purple color.
put a heat barrier on top of your mix it will also help keep the oxides down and the temp more consistant.
Mine (when I get great fillout and boolits that drop a little oversized) is run at about 7 - 8 on a Pro-4 20 pound pot...
At that temp I my alloy Turns kinda golden, then turns blue...then purple.
Once I finally got a thermometer I checked to see what temp I was running at. About 800 - 850. Sometimes buries the needle. Guess I need to start adding a little more tin to my WWs to keep the fillout and keep the temp down. :roll:
webby4x4
05-05-2009, 01:08 PM
put a heat barrier on top of your mix it will also help keep the oxides down and the temp more consistant.
Heat barrier... is that a fancy term for a lid?
hammerhead357
05-05-2009, 11:55 PM
Could be a lid or like some of us use a layer of new unsented kitty litter. I use a layer about 3/8 in. thick. It does wonders. I flux with it sitting on top of the melt.
A word of warning let it sit on top of the melt for about 5 min. before stiring the melt to flux. This will drive the moisture out of the litter.
Oh yes I think powdered charcoal will work and would be a good flux. I just haven't tried it but I think some here do use it......Wes
Jaybird62
05-06-2009, 12:06 AM
I got some of the blue/purple last week from smelting some roof flashing. I also got the gold color when I smelted some old plumbing pipes and what looked like very old ingots poured into the ladle end of a hammer mold. The ingots from the flashing is so pure that I can bend a 1-pound RCBS ingot with my hands.
runfiverun
05-06-2009, 07:53 PM
with my 40 lb pot i use the kitty litter and a 1/2" piece of steel as a lid it's a great place to set my molds too.
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