What does a yellowy tint on bottom of a Lead ingot indicate?

[gwpercle]

Don't panic about the yellow color .
When lead is heated to a too high temp. the surface develops a 'Rainbow" of color on it ... Pure lead will develop the most vivid rainbow colors , other alloy's to lessor extent ...but it's just the heat ...
you will see blue's , red' s and yellow's ... common when "smelting" large batches on a big gas burner ...it gets hot .
The colors can stay for years or fade the dark colors are easiest to see but the yellows appear first , before the blues ... It looks like the ingots were cast in the yellow heat range before the melt got hot enough to make blue colors . Don't worry about yellow color , test hardness and carry on .

Zink contaminated looks like oatmeal ... I don't see that in your ingots . The melt may have gotten a few zinkers but not enough to "contaminate"...your ingots all are smooth and should melt and cast up just fine .

Another thing ...it isn't rocket science ... don't overthink it .
I cast with 50-50 mix of COWW and soft scrap lead that = BHN of 8-9 . That hardness works for all handgun bullets and 30 cal. rifles . Most folks don't realize that Fit of bullet to bore is much more important than hardness . Most folks shoot bullets that are Too Hard .
A undersized hard bullet will lead your bore like all get-out ... get the size right and shoot BHN 8 to 10 and you will do fine .

Gary

 

[JimGnitecki]

Don't panic about the yellow color .
When lead is heated to a too high temp. the surface develops a 'Rainbow" of color on it ... Pure lead will develop the most vivid rainbow colors , other alloy's to lessor extent ...but it's just the heat ...
you will see blue's , red' s and yellow's ... common when "smelting" large batches on a big gas burner ...it gets hot .
The colors can stay for years or fade the dark colors are easiest to see but the yellows appear first , before the blues ... It looks like the ingots were cast in the yellow heat range before the melt got hot enough to make blue colors . Don't worry about yellow color , test hardness and carry on .

Zink contaminated looks like oatmeal ... I don't see that in your ingots . The melt may have gotten a few zinkers but not enough to "contaminate"...your ingots all are smooth and should melt and cast up just fine .

Another thing ...it isn't rocket science ... don't overthink it .
I cast with 50-50 mix of COWW and soft scrap lead that = BHN of 8-9 . That hardness works for all handgun bullets and 30 cal. rifles . Most folks don't realize that Fit of bullet to bore is much more important than hardness . Most folks shoot bullets that are Too Hard .
A undersized hard bullet will lead your bore like all get-out ... get the size right and shoot BHN 8 to 10 and you will do fine .

Gary

Thanks for the explanation, Gary. I hope you are correct.

Jim G

 

[lightman]

I use the stuff that you "shock" swimming pools with. Toilet bowl cleaner is probably cheaper.

 

[Jim Watson]

Empiricism. Melt, skim, cast. Do the bullets fill out?

Just because sulfur is yellow does not mean its compounds and combinations are.
Frex, sulfur dissolved in anhydrous ammonia is purple.

 

[JimGnitecki]

Empiricism. Melt, skim, cast. Do the bullets fill out?

Just because sulfur is yellow does not mean its compounds and combinations are.
Frex, sulfur dissolved in anhydrous ammonia is purple.

1. If I "melt, skim, cast", and it turns out there IS Zinc, isn't that going to pollute my melt furnace?

2. I would also be risking some good wheel weight alloy and Tin, as pure Lead is way too soft (BHN = 5) to use alone form bullets that will be subjected to 17,000 to 18,000 psi. I need BHN =11. So, I'd be risking more than the 12 lb of questionable Lead.

Jim G

 

[Jim Watson]

So cast some bullets out of JUST the doubtful stuff.
If they come out, only then melt them back into your alloy.
Ruin your pot? I don’t know myself but there are people posting about a slow melt to remove known zinc content.

Or just scrap it and avoid all worry.

 

[Rodfac]

I had considered sulfer or rust from sitting in a cast iron mold?

That's my take on it....if it's zinc, you'll know by the lousy casting properties....incomplete fill out of driving bands, etc. If you smelt your wheel weights at 725 degrees or less, the zinc will float on top...easy to skim off. Rod

 

[SterlingBullet]

Here is a funny thought; maybe you have lead-plated gold ingots and the plating is wearing off. Wouldn’t that be nice.

 

[gwpercle]

1. If I "melt, skim, cast", and it turns out there IS Zinc, isn't that going to pollute my melt furnace?

2. I would also be risking some good wheel weight alloy and Tin, as pure Lead is way too soft (BHN = 5) to use alone form bullets that will be subjected to 17,000 to 18,000 psi. I need BHN =11. So, I'd be risking more than the 12 lb of questionable Lead.

Jim G

1. No ...simply melt 1-2 ingots in any small pot / pan and cast a few bullets in a mould ... zink is not going to "pollute" or "contaminate " a pot , furnace or mould .
When zink is in a lead alloy it gives it a rough oatmeal appearance and bullets cast don't want to fill out .
They will appear rough and the melted alloy when stirred looks like cooked oatmeal .

2. Don't add anything to the ingot metal ... you are melting and casting to see if it is "zink contaminated" you will not be shooting the bullets ...just seeing how they look after casting . If they drop smooth and sharp edged ... the ingot metal isn't contaminated with zink ... test the hardness and carry-on .

Your ingots appear smooth surfaced ... I don't see any evidence of zink from photo's .
Gary

 

[JimGnitecki]

1. No ...simply melt 1-2 ingots in any small pot / pan and cast a few bullets in a mould ... zink is not going to "pollute" or "contaminate " a pot , furnace or mould .
When zink is in a lead alloy it gives it a rough oatmeal appearance and bullets cast don't want to fill out .
They will appear rough and the melted alloy when stirred looks like cooked oatmeal .

2. Don't add anything to the ingot metal ... you are melting and casting to see if it is "zink contaminated" you will not be shooting the bullets ...just seeing how they look after casting . If they drop smooth and sharp edged ... the ingot metal isn't contaminated with zink ... test the hardness and carry-on .

Your ingots appear smooth surfaced ... I don't see any evidence of zink from photo's .
Gary

This sounds easy to do and foolproof. I'll try it! Thanks for the suggestion!

Jim G

 

[JimGnitecki]

I found that a local store sold Muriatic Acid in 1 liter size, so I bought 1 liter, and used an eye dropper to drop some of the acid onto one of the ingots that exhibit the yellow color. It did NOT bubble. Just spread out on the surface with no visible chemical reaction.

Does this mean that there is no zinc?

Jim G

 

[Y-T71]

In my experience, no zinc.

 

[gwpercle]

I found that a local store sold Muriatic Acid in 1 liter size, so I bought 1 liter, and used an eye dropper to drop some of the acid onto one of the ingots that exhibit the yellow color. It did NOT bubble. Just spread out on the surface with no visible chemical reaction.

Does this mean that there is no zinc?

Jim G

The acid test shows ... No Zinc ! There would be a Vigorous Foaming action if zinc were present !

The yellowish color is from when the ingots were poured at a high heat ... common , sometimes a blue and reddish colors are seen ... high heat rainbow , pure lead gives the brightest colors .

You are good to go .
Gary

 

[JimGnitecki]

Thanks, guys!

Jim G

 

[JimGnitecki]

Hey guys, I receievd my 5 lb ingot of "Superhard" (30% Antimony, 70% Lead) from Rotometals yesterday. Take aLOOK at it:



Notice the YELLOW tint?

That yellow tint makes PERFECT sense for Lead that has been heated high above its normal melting temperature. It HAD to be overheated in order to alloy the Antimony into it, since Antimony does not melt until it gets to 1167 degrees F !

But this yellow appearance looks similar to the yellow on the Lead ingots discussed above that I had been given:



So, yes, the yellow on my ingots appears to be the predictable result of heating the Lead higher than needed during the ingot pouring process.


THIS on the other hand is apparently what Zinc contaminaiton looks like (photo below grabbed from a video showing what Zinc contaminaiton in lead looks like):



The Zinc looks almost like rust, and tends to have swirl patterns on what was the poured top of the ingots.

Jim G