Colour of smelt?

[Swede 45]

Sorry if this is obvious for you guys, I´ve tried seaching and stickies for this, but are getting crosseyed trying to read it all and come to a conclusion.. so therefore I put my own Q´s here.

Got a batch of unknown lead today from a friend.. he had got from someone else, so there is no way to tell the source of this.. as usual! (The original donor had used it for casting fishing sinkers. The lead was poured into old cans in different layers, some harder then others..)

Throw it in my smelting pot and heated it up on the propane stove.. unfortunally I got distracted by a phonecall while it heated up..
I didn´t had a thermometer handy either.. (that one is stuck in my casting pot!) but the smelt seemed to be pretty hot when I returned.

I fluxed the smelt with sawdust and candlewax.. I had a thick metallic crud floating on top that wouldnt melt so I skimmed that off.
My first thought was thats Zink?

#Does a small amount of already molten zink in a contaminated batch float on top, (if temp is at par with lead but below zink) of an otherwise liquid melt when re-melting, or does it turn the whole melt into oatmeal?

After getting the course crud out the surface of the smelt quickly turned golden/purple/blue.. also formed a skin on top (like skin on warm milk) Fluxed once more and could skim alot more gunk out, then surface quickly took to nice oily colours again, with the same skin on top.
I poured my ingots and they took quite a while to turn solid..

# Was the smelt temp to high?/ to low?
# Was the crud I skimmed of good stuff (tin and such?)
#Would it be a good idea to remelt this batch, return the gunk, flux it some more, and try to do it all over again at a more controlled temp?

Pic of one casted ingot:


Pic of smelting pot with the colourful skin on top:


Thank you..
Per

[txsnowman2k2]

short answer, too hot... i would keep this batch set aside until you free up your thermometer and re-smelt since you have no idea what the temp was. when one has an "unknown" batch/source of lead, it could be different things. could be zinked. could be you cooked off all the tin. i'd keep it aside for know, let some of the experts on the forum chime in...tx.

[bangerjim]

Never.....EVER!!!!!!!......get distracted by ANYTHING while melting lead! Turn off the burner if you walk away.

We have NO idea what you have. As said above, set it aside to mess with later. The technicolor rainbows are normal for pure lead that is way too hot for way too long.

The "stuff" on the top is probably a good deal of your alloy materials (Sn, Sb) that just got too hot and oxidized too severely to easily flux back in.

A little Zn does not hurt. A LOT does.....causes lower weight and potentially severe fill out problems when casting.

You MUST be very alert and at the pot at all times when melting. There is this thing called voicemail!

Good luck.

bangerjim

[Swede 45]

Yeah.. I´m looking for some clever expert guys to chime in..
Theres quite a few Q´s here..
If the batch was contaminated with zink?.. would that float on top (if the heat was high enough to melt the led in the stew but not the Zink, like it does if you accidently get a Z ww into a otherwise pure melt?) I dont know how Z in a already melted batch behave when you re-melt it?

And yeah.. i´ve set it aside, and also saved all the gunk.. if that is some good stuff that should be put back?

Bangerjim: yeah.. I´m the kind of guy who learns by making mistakes and then tries to figure out what went wrong!
Right now I´m trying to find out if this is something that I can re-do and save, use as is, or what?

(i´m not going to use this batch as a sole alloy and cast this as is.. but preferably be used in a mix later on..)

[dubber123]

A hardness tester is handy. If it's around 14 in my experience, it's probably WW material. (Air cooled). 8 or less is more towards pure stuff. I have never had the opportunity to cast with anything harder, so no experience there.

I'd simply clean out my casting pot and fill with this stuff and give it a whirl. If it casts well and the resultant boolits weigh close to whatever you were using before, use it up. If they cast notably on the heavy side, they have more lead content, and are probably a little softer.

[nagantguy]

I've seen those exact colors when melting range scrape lead. Same temps as always, I wrote it off to all the partial copper jaket material flowed and filled out molds fine after a flux or 3,with saw dust the colors lessen but don't disappear. The boolits it makes shoot fine, my casting partner just won 3rd place high masters at a pistol event with them shot as cast lubed with Lee alox.

[bangerjim]

I've seen those exact colors when melting range scrape lead. Same temps as always, I wrote it off to all the partial copper jaket material flowed and filled out molds fine after a flux or 3,with saw dust the colors lessen but don't disappear. The boolits it makes shoot fine, my casting partner just won 3rd place high masters at a pistol event with them shot as cast lubed with Lee alox.

Has nothing to do with copper. Those are the exact colors pure lead turns when it get too hot. It does nothing detrimental to PURE lead to overheat it. It DOES do detrimental damage to an alloy......oxidizes some/all of your Sn/Sb if an alloy containing those is overheated. And that oxide will float on the top as a gray "stuff". If it was not left cooking too long (30 minute phone call?), you can easily flux/reduce it back in with pine sawdust and beeswax. Or any of the million other "things" people claim they use!!!!! Carbon-based life forms seem to work the best.

Zn WILL float on top as long as you did not leave it cooking long enough for the melt to get to the melting point of Zn. Then it all melts together!!!!! Most stuff and metals (Fe, Cu, Zn, and others) will all float on molten lead. Even rocks! Zn and Pb will alloy together at higher temps. Then you have to strip the Zn out by using either sulfur or copper sulfate (covered in several threads on here....do a search). Those also strip all the Sn and Sb out, so you basically start over with pure Pb. That is why it pays to sort well and watch the pot temp.

You can cast just fine with Zn contamination.......just add more Sn ($$$$) to decrease the surface tension of your casting soup and get good fill-out. And your boolits will be lighter depending on the % Zn you have.

But............NEVER "throw the whole pot out because of a little zinc contamination"!!!!! That is just...........well.........not too smart.......and is expensive.


Have fun!!!!

bangerjim

[lwknight]

No zinc, just too hot.
Looks like it's probably nearly pure lead.

[nagantguy]

Love smelt, very funny. I learn something almost everyday here. I always thought my indoor range scrape was close to pure when I melt it down. Mix those igots with igots made of ww in my own alchemy like formula that gives me my perfect pistol/ revolver boolits. My melt looks just like that on ocassion, never left it untended what I got out was soft didn't think it was that close to pure.

[txsnowman2k2]

I like second smelt picture color much better...ha.tx

[Swede 45]

That batch contained alot of zink and other gunk..
The ingots, after getting most of the gunk out contained:
94.9Pb, 2.15Sn, 2.24Zn and 0,47 wolfram..
And wolfram doesn´t go well with tin.. so that was probably the cause of the exessive gunk and thick skin..the wolfram probably reacted with the tin and was skimmed off. When all the tin was gone, there was a small amount of W left..?

[triggerhappy243]

not much of a fish eatin person... more catch and release. but i do love a good sense of humor. not much left in this country that is funny... good job phineas

[mikeym1a]

No zinc, just too hot.
Looks like it's probably nearly pure lead.

That was my thought on looking at the pictures. It simply looks like nearly pure lead that was heated too hot. As said elsewhere, you need your thermometer to tell what it is. Lead melts at about 625, lead/tin/antimony alloys melt around 500, zinc melts at 725, if memory serves. Free up your thermometer, and remelt this mystery metal, slowly, checking temps along the way. It will tell you what you want to know. mikey

[lwknight]

Oh well... win a few....
A small amount of zinc usually makes oatmeal looking slush on top. I guess the pictures were deceiving.

[Geezer in NH]

not much of a fish eatin person... more catch and release.

Just for the record there is no such thing as catch and release dippin'if you know what I mean

[triggerhappy243]

geezer... no, i do not know what you mean. i was referring to the one reply with the fish "smelt".

[Blanco]

While I have not been casting as long as many of you here have. I would like to add some of my observations. They run counter to some of the advice given. While I would agree about the bluish skin being from high temperature,I have seen this form from adding an alloy with a known Zinc content. The color and accompanying lumpy dross followed.
I have also seen the bronze color appear after adding an alloy with known copper content.
Some may say that the color has nothing to do with the alloy content but I have done it and seen it.
I have been wrong once or twice.

[lwknight]

I only had zinc get mixed one time and there was no blue or yellow colors. Just clumpy dross that would not go away. The ingots cast soft but soon got hard enough to break before bending even when poured thin.