What's this in the melt?

[abcollector]

I've attached a couple of pictures of a pot of w/w's that I had bought off ebay in ingots that needed to be cleaned (thanks for all the posts in another thread about cleaning your ingots before they go into the bullet pot). Anyway, there was an ingot or two that looked like it may have been linotype that I also included in the melt to clean up. I don't normally have linotype laying around so I thought that I'd just add it as it was only a pound and a half to about sixty pounds of w/w.

This is what the melt looked like after it was melted and attempted to flux. What is this stuff? Is it from the linotype? How do I flux it back into the melt? High temperature (~725˚F) seemed to make it worse amount wise but I still could get rid of the stuff at a lower temp.

Thanks guys!

[kooz]

Looks like WWs @ about 520-580 degrees.

[454PB]

Yes, that's the antimony foaming on the top. At 725 degrees, it should flux right back into the melt. Are you confident in your thermometer?

[HeavyMetal]

You ain't hot enough!

I also don't see a thermometer! Picture looks like half melted WW at Low temp!

1 and a half pounds of Lino woulds not do this to a melt.


Looks like you've got this rig set up on top of a porpane stove? You may have to play with the adjustments, if any , to get a hotter flame.

If you have one what type thermometer are you using?

[abcollector]

Okay, thanks for the replies. That's good news that it seems like it wasn't hot enough.
Yes, I do have an RCBS thermometer and when I checked it about ten minutes prior to this pic being taken it was ~720-725˚F. I know the thermometer is accurate to with in 2˚F from the "test" that I did with it.
So I'll run 'er up to about 780˚ today if I have the time. So I guess I know what antimony looks like now.

Thanks again.

[Just Duke]

What is the temp where you are casting? If it is winter where your at and you just happen to have a breeze, it will almost solidify the top surface of you lead sir.

[fourarmed]

I'd be interested in hearing about your "test" of the thermometer. A friend's thermometer routinely goes to 1000 degrees in a Lee pot, but the alloy casts like the same alloy in my Mag-20 when my thermometer reads 800.

[looseprojectile]

Had the same thing happen to me. All went into the dross can. The next time I smelted, I melted the contents of the dross can. Got twelve ingots of what I labeled crap. Now I know what it can be used for. This was the first time I had seen this. Lots of mushy stuff.
My problem lately has been getting the boolits soft enough. Probably can use this process to separate out the stuff that makes the alloy harder.
Life is good

[Marlin Junky]

Linotype melts at under 500F. What you have looks like zinc floating on top. Did you perform a hardness test before trying to melt the bars you suspected were Linotype?

MJ

[Ricochet]

One of the harder, high-antimony type metals could do that. Not linotype, though, it's eutectic (no mush) and melts at about 473F.

[standles]

On a tangent...

I actually keep a 1/4" AL plate over the top of my bottom pour pot to hold heat and help on oxidation some. It also serves as a nice warm spot to rest moulds.

It is also a good fingertip cooker if your not careful

Steven

[cbrick]

I agree with Ricochet, I've had this happen to me a couple of times in the past, it looks just like silver oatmeal. It flux's right back in and is NOT Zinc. Pure SWAG on my part but it seems that there could be a temp at which the tin/lead part of the alloy melts (such as solders that can melt in the high 300 degrees) and the antimony (the highest melting temp in the alloy) is just beginning to melt.

The first time I saw this the melt wasn't yet up to temp and this silver oatmeal started forming on top. I waited for the alloy to come up to casting temp which I always do before fluxing. At 700 degrees I sprinkled sawdust onto the silver oatmeal and it just disappeared, even before stirring, most amazing thing I've ever seen in a lead pot.

After fluxing, this pot of alloy cast boolits just as well and of the same weight and BHN as this and previous batches.

Bottom line; its antimony, flux it back in or loose it.

Rick

[454PB]

Yes, I see it all the time in monotype.

[abcollector]

Okay guys. I was able to spend some time this evening re-smelting that pot of melt in the photo's from yesterday evening. Two things were needed to flux the "mush" back into the melt. One was higher temperature (~800˚F) and two, a large piece of flux. I use beeswax, about the size of a quarter. I dropped it on the surface, start to stir and as it's melting, whoose, it ignites and flames until it's gone and then all I have left is a bunch of black crap floating on top which I skimmed off. The melt is beautiful looking. I really think the key was a larger piece of flux and don't think that 800˚ is necessary. I'll try 725-750˚ next time.

I think 454PB and a few others nailed it- it's antimony foaming.

[abcollector]

fourarmed-
the "test" I did with the thermometer was really a test to test if lead is commercial pure or not. This was from Bill Ferguson, aka, bulletman.

"The easy way to test your lead is melt a pot of it, insert a thermometer so it hangs freely in the center and go to about 700F and turn off heat.

You can make a plot of temperature decrease against time (minutes usually) and when the lead cools to 621F it will stay at that temperature until all solid IF IT IS 'commercial pure' which is 99+%. If it does not maintain a constant temperature for several minutes (assuming about a 20 lb pot) then it is not 'pure'.

If the thermometer remains at a constant temperature, whether higher or lower than 621F then the difference is the calibration for your thermometer."

My RCBS thermometer actually stayed at 619˚F for those several minutes until the melt was solid. So, I guess you could say the calibration of my thermometer is ~2˚ off.

Works for me.