Newbie caster--Newbie mistake? Did I get Zinc contamination?

[DaveSpud]

I'm working my way through my first bucket of wheel weights. I was very careful (I think?) to sort lead from zinc and steel.

My first two batches of ingots came out as I expected. Yeah!

Last batch, though...

As I was getting ready to pour, I felt what seemed like clay or thick cottage cheese on the sides/bottom of the pot. The first two ingots came out fine, but the rest looked like crumbly clay. Though they did hold together. AS I was pouring, the "lead" cooled almost instantly in the ladle and molds.

Did I get zinc contamination? Or was my lead too cold? (Its like 20 degrees here.)

ETA: I looked at Furtunecookie45LC's Youtube video on zinc contamination. My ingots look a lot like his...

[JonB_in_Glencoe]

I'm working my way through my first bucket of wheel weights. I was very careful (I think?) to sort lead from zinc and steel.

My first two batches of ingots came out as I expected. Yeah!

Last batch, though...

As I was getting ready to pour, I felt what seemed like clay or thick cottage cheese on the sides/bottom of the pot. The first two ingots came out fine, but the rest looked like crumbly clay. Though they did hold together. AS I was pouring, the "lead" cooled almost instantly in the ladle and molds.

Did I get zinc contamination? Or was my lead too cold? (Its like 20 degrees here.)

ETA: I looked at Furtunecookie45LC's Youtube video on zinc contamination. My ingots look a lot like his...

Could be either, I suspect you didn't have a thermometer.

Here is some pictures I posted when I had one batch of COWW get contaminated with Zinc.
http://castboolits.gunloads.com/show...ing&highlight=

[DaveSpud]

One suspicious piece of data that might mean temperature (and no, I don't have a thermometer) is that I fluxed with both sawdust and then wax, and neither flamed. Just smoked like crazy and the sawdust turned dark brown, then black.

Your thread reminded me of the acid test--I've got some muriatic for the pool. I'll drop some on the ingots and see what what I get.

ETA: I was wrong, no muriatic. Used it all last summer. Is there anything else that will give a good test for zinc?

[lwknight]

Put a bigger fire on it! Don't be so scared to heat it up to 650+. The zinc will float up long before melting if you
are just a little careful not to exceed 700 degrees and heat slowly with some seed grease in the bottom.

I literally mean some melted alloy in case you thought I really meant grease.
Its kinda like frying bacon, things just go better with a little grease already in the skillet.

Really I think you had the pot just barely melted. The crumbly was not zinc. It was hot lead setting up.

[mikeym1a]

Some drain cleaners are sulfuric acid. I imagine that would give you a reaction. For that matter, you might use vinegar. That might give you a reaction, but not sure. You really do need a thermometer. They are a little pricey, but well worth it. When you smelt, or process WW's, you can do it as low as 600degrees. Zinc melts much higher, about 780, so if you do miss some zincers, they will just float to the top, at 600. I processed some WW's last week, and it was quite cold, but I wanted to get it done. Had quite a bit of 'oatmeal' on top, but my thermometer said I was in the safe range. I threw in a big handful of sawdust, and stirred it in real good, and most of the 'oatmeal' went away. I think it was just too cold and windy. Hope this helps.

[DaveSpud]

Yup. A thermometer is in order. I'm starting to think it was just cold. The thick stuff wasn't
floating, it was on the sides. A cold wind was blowing the burner flame. I'll see if we have some drain cleaner or something to test.

[220swiftfn]

Sounds like you were still in the slush stage..... Get a section of sheet duct to use as a windbreak, it'll help A LOT.......



Dan

[amosfella]

Some drain cleaners are sulfuric acid. I imagine that would give you a reaction. For that matter, you might use vinegar. That might give you a reaction, but not sure. You really do need a thermometer. They are a little pricey, but well worth it. When you smelt, or process WW's, you can do it as low as 600degrees. Zinc melts much higher, about 780, so if you do miss some zincers, they will just float to the top, at 600. I processed some WW's last week, and it was quite cold, but I wanted to get it done. Had quite a bit of 'oatmeal' on top, but my thermometer said I was in the safe range. I threw in a big handful of sawdust, and stirred it in real good, and most of the 'oatmeal' went away. I think it was just too cold and windy. Hope this helps.

Unless you really know how to handle strong acids, DO NOT try testing with sulfuric acid. Also, sulfuric acid is a very inconsistent beast to deal with. You have to know the weight of acid vs water to be able to have consistent results. At one ratio, it will dissolve lead, and at another, it will dissolve zinc. Also, it can be temperature sensitive...
Some times it will react very violently with the material it is dissolving, and will splatter everywhere... It will eat skin very quickly, and could leave you scarred, permanently disfigured, or blind.
Easier to test with remelting with more heat, and stir with a tree branch that's partially burned. I use one that's about 3" in diameter, and about 3-4 feet long. Burn the end to charcoal and pull out of the fire. You can still with it while it's still on fire. The length keeps you from getting heat radiation burns on your hands and arms...

[bangerjim]

Unless you really know how to handle strong acids, DO NOT try testing with sulfuric acid. Also, sulfuric acid is a very inconsistent beast to deal with. You have to know the weight of acid vs water to be able to have consistent results. At one ratio, it will dissolve lead, and at another, it will dissolve zinc. Also, it can be temperature sensitive...
Some times it will react very violently with the material it is dissolving, and will splatter everywhere... It will eat skin very quickly, and could leave you scarred, permanently disfigured, or blind.
Easier to test with remelting with more heat, and stir with a tree branch that's partially burned. I use one that's about 3" in diameter, and about 3-4 feet long. Burn the end to charcoal and pull out of the fire. You can still with it while it's still on fire. The length keeps you from getting heat radiation burns on your hands and arms...

That is why you use HCL (hydrochloric or muriatic pool acid) rather than H2SO4 (sulfuric - which is plain old battery acid). The 30% HCL you get in pool stores works very well.....fumes like crazy so be careful. You can get an eye dropper of sulfuric acid out of your car battery (which contains lead)! But I do not recommend H2SO4.

I use my pool acid all the time to test. No problems. You just have to "respect" it as you would a gun or explosives. But it is a very common acid readily available at many stores depending on if you are in a "pool friendly" weather area.

It all has to do with hydrogen ion strength and activity. Battery acid is pH of ~3-4..........Coke is pH of ~4. Different hydrogen ion potentials. I can't remember the last time I enjoyed a tall cool glass of battery acid!

HCl is a fast and efficient way of testing to see if WW's are Zn if all other methods are not conclusive.. Just have some water in a bottle to wash it off! And wear eye protection!!!!!!!!!

And MOST household drain cleaners are caustic-based not acid-based. Acid-based cleaners are VERY dangerous because pouring acid into water can sometimes cause violent exothermic chemical boiling! The other way (water into acid) is EXTREMELY explosive! Remember: "A comes before W" in the alphabet. Sodium hydroxide or potassium hydroxide have been the standard "safe" drain cleaners used for a long time. Some powdered versions even have aluminum flakes in there for that "bubbly" action. NaOH just LOVES aluminum! And hair. And grease. No reaction to lead or Zn.

banger

[amosfella]

I know that NaOH loves Aluminum. Friend, against my advice, set up a bluing tank on an aluminum rack. and proceded to make a homemade bluing solution using lye to raise the boiling point to get the bluing action... Needless to say, it did not go as planned and the stand kinda dissolved before his eyes...
Charcoal will remove zinc from lead quite nicely, but the zinc has to come in contact with the charcoal, hence the stirring with the branch for around 5 minutes.

[DaveSpud]

Tell me more about using charcoal on zinc contamination! Sound like you take a partially burned brach and stir it in the lead? Let it burn and smoke while you stir? Anything else to it?

By way of update, I tested the suspect ingots with drain cleaner--could not find any ingredients, so no idea if this was definitive. But no reaction. I re-melted the ingots, and they came out looking pretty good. Maybe it was just temperature. Have not had a chance to get the lead thermometer, but I'll get it this week before I smelt any more.

[JonB_in_Glencoe]

Tell me more about using charcoal on zinc contamination! Sound like you take a partially burned brach and stir it in the lead? Let it burn and smoke while you stir? Anything else to it?

By way of update, I tested the suspect ingots with drain cleaner--could not find any ingredients, so no idea if this was definitive. But no reaction. I re-melted the ingots, and they came out looking pretty good. Maybe it was just temperature. Have not had a chance to get the lead thermometer, but I'll get it this week before I smelt any more.

YES you are fine, you don't have zinc contamination.

[amosfella]

Tell me more about using charcoal on zinc contamination! Sound like you take a partially burned brach and stir it in the lead? Let it burn and smoke while you stir? Anything else to it?

By way of update, I tested the suspect ingots with drain cleaner--could not find any ingredients, so no idea if this was definitive. But no reaction. I re-melted the ingots, and they came out looking pretty good. Maybe it was just temperature. Have not had a chance to get the lead thermometer, but I'll get it this week before I smelt any more.

For reasons I don't understand, Zinc seems to float after exposure to charcoal, or at least become less dense. The stirring action seems to allow the zinc to float, allowing you to slowly lower the temp until the lead starts to get gummy, then raise it back up just a bit above the gummy point. Just to the point that it's not sticking to anything. That allows the zinc to float off, but all contaminates, ash, zinc, etc. come to the top easier if the lead is agitated.
I know a lot of people who get their knickers in a knot over the idea that there might be a little bit of zinc in their lead, saying it's no good for anything, should sell it as scrap, etc. However zinc is not an enemy. It's the easiest way to clean aluminum, silver, gold, platinum, palladium, rhodium, and the rest of the platinum group metals out of lead during smelting. Lead ore is often times used to bring iron ore down to more pure iron, and iron sands often times contain these metals. In a molten state, lead acts as a solvent to remove these metals from iron, either ore or scrap. Zinc is added after to bind these metals, and remove them from the lead, and carbon, either in the form of charcoal or coke is added to the molten metal that is being agitated remove the zinc. Lead is usually electrofined from there to remove the arsenic, antimony, bismuth, tin, etc.
The reason I said a burning branch is that I usually pull it out of a fire which I have used to reduce the end to charcoal, it's easy to control (a 2x4 from a fire would do the same thing, I just had branches available for free), and the reason I set it on fire was to prevent possible tinsel fairies. That's the same reason I left it on fire. If I quench it, the charcoal readily absorbs water, and that's bad news in molten lead, and the fire doesn't hurt anything as long as there's enough room between my hand and the part I burned....
I also pour into molds that are big enough to hold heat from re skimming after pouring. Usually the zinc that doesn't come out during the stirring and skimming will come out after pouring. The zinc manifests as a oatmeal like froth that has an entirely different consistency and a duller grey than the lead. When you see it, you'll know it now that you know what to look for.
As a side note, you can have up to about 1% zinc in your lead and still cast great bullets, as the zinc acts as a hardening agent, and under that percentage it doesn't increase the surface tension of the lead to cause improper fill out in the mold.

[DaveSpud]

That is very helpful info. Thank you.

[40-82 hiker]

Put a bigger fire on it! Don't be so scared to heat it up to 650+. The zinc will float up long before melting if you
are just a little careful not to exceed 700 degrees and heat slowly with some seed grease in the bottom.

I literally mean some melted alloy in case you thought I really meant grease.
Its kinda like frying bacon, things just go better with a little grease already in the skillet.

Really I think you had the pot just barely melted. The crumbly was not zinc. It was hot lead setting up.

I smelt no higher than 675 F. Zinc melts at something like 780 F. Also, sort carefully. I cut all lead going into the pot. There are other threads on zinc and lead ingot photos. Be careful, as some zinc weights are now being made with the same molds as old lead COWWs. That why I cut...

[RogerDat]

I just bought the Lyman thermometer but other than having lead and alloy melt temp ranges around the edge, being made in China and costing more I don't think it was much different than this USA made thermometer from Tel-Tru http://www.amazon.com/Tel-Tru-LT225R...ef=pd_sbs_sg_4

Clips look different in picture but my Lyman came with the same spring clip as the Tel-Tru has in its picture but if you want the Lyman it's available here http://www.amazon.com/Lyman-2867793-.../dp/B001TQ8Y6Q

[DaveSpud]

Thanks, folks. Just got a lead thermometer to assure I can monitor smelting temp going forward.

[WILCO]

Thanks, folks. Just got a lead thermometer to assure I can monitor smelting temp going forward.

I always smelt in small batches. It's hard to screw up large batches that way.