Silver Sludge while fluxing

[Sloffie]

I have melted down my first batch of clip on wheel weights. Now I used both paraffin wax and a wooden stick to flux.

What was weird is a thick silver sludge appeared to float on the top of the melt. It did not mix back in. Chucked it into the dross bin, but I kept it. I am afraid it might be something important I have removed from the melt as it was quite a bit.

I used a Lee Ingot mold to cast, but the ingots turned out strange. I water quenched them to see what would happen. some cracked and one broke. Very weird.

I will post some photos of my ingots and you can comment.

What I want to know is is it possible to flux out antimony and tin by accident?

[Sloffie]

Wheel Weight Lead:

http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/CastIngotsJune12-04.jpg
http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/CastIngotsJune12-01.jpg
http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/CastIngotsJune12-02.jpg
http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/CastIngotsJune12-03.jpg
http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/CastIngotsJune12-05.jpg

Sludge:
http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/CastIngotsJune12-08.jpg

Also please look at these ingots:

http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/CastIngotsJune12-07.jpg
http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/CastIngotsJune12-06.jpg

Are these crystalline formations normal?

Excuse the ugly ingots, I am still getting a hang of it. One day I will have nicely rounded ingots.

[500MAG]

Did you check each wheel weight to prevent throwing in zinc? What was your pot temp?

[runfiverun]

temp.
the gold color is from the tin oxidizing.
you let the pot sit.
you got just barely past the solidous stage then fluctuated back and forth.
it does not take long for a batch of lead to go from melted to solid.

[popper]

temp+1. Looks like all the was didn't melt and burn off.

[454PB]

Not to worry, you can't "flux out" tin and antimony. You could oxidize them out, but it takes a long, long time at high temperature.

I'd suggest you raise the temperature a bit, or let the pot heat a little longer before fluxing. That clumpy dross indicates that the melt was not fully up to temperature.

It's normal for quenched ingots of wheel weigh alloy to crack or break, and there's really no reason to quench them unless you're short of ingot moulds.

[40Super]

I'm agreeing with the others on this one, doesn't look like it was fully liquid and the mass couldn't form into a solid structure. Got the whole pot up to 625F to 650F(as long as it isn't pure), and give it some time while mixing to make sure all of it is melted fully.

[Defcon-One]

Man, a lot was posted in the 3 minutes it took to type this, but here's what I said:

I'm with runfiverun! Your temp was too low when you skimmed it. The silver sludge is probably Lead and Antimony, possibly some tin as well. Temp should be 650-700 when you flux it (I like 700 Deg. F). I use Pine Sawdust for flux. I think it works better than wax. Adding about 1 rounded tablespoon for each 10 lbs. of lead will do it. You Flux Tin and Antimony back in, not out. It is called Reducing and is the opposite of Oxidation.

Spread the sawdust on top, stir it in aggressively and watch the metal mix back in. After the sawdust turns to charcoal, stir again to clean the mix and skim off the gray ash, then pour ingots. If the smoke bothers you, you can light it with a match it will burn off with much less smoke.

Your ingots were setting up while you were still pouring them. That's why they look lumpy and crystalline. Pour with hotter lead so it takes longer to solidify or pour faster. The broken ones always have that grainy interior it is normal for a hot ingot that fractured. It is the Lead/Antimony matrix showing because the ingot broke while it was just barely solidified.

[Sloffie]

WoW! Thanks for all the info. I did not melt the lead in my LEE pot, I just used an old SS fondue pot I picked up for a buck. Used it on a gas stove. Guess I will throw all of this into my LEE pot and get it heated up properly and stir the metal back in.

Oh and the gold in the photos is from the flash of the camera. The ingots are not gold. And I did sort the wheel weights by checking each one with a pair of side cutters. I do not know what my temperature was as I do not have a lead thermometer.

Thanks for the advice!

[Marlin Junky]

rule of thumb is you need to get your alloy to 100F above its melt temp in order for it to pour correctly. The boolit in your avatar is also evidence that you're not used to working with enough heat yet.

MJ

[popper]

Nope, the 'gold' in the first 4 pics is left over wax that has burned but is not gone. Melted lube does the same until it's gone. You pot will work fine to flux if done outside. I was surprised to see the amount of junk on the bottom of a smelted? ingot. I just melted WW in a SS pan,skimmed, fluxed, cooled and dumped it out. Black dust all over the bottom. You don't want it in your bottom pour pot.

[lwknight]

Yup, you did not melt it good.
Then you dumped the molds too hot.
More heating and more cooling is what you need.

[leadbutt]

Really look into getting that thermometer. Its worth the piece of mind.

L. Bottoms

[zxcvbob]

Zinc contamination would do that, and it doesn't take much, but I don't think that's what it is.

I think you didn't finish melting your lead. Pure lead and Linotype and 63/37 solder each melt all at once. Most alloys melt over a range of temperatures (call the solidus and liquidus) and in between they are mushy. The bottom of your pot was fully melted and the top wasn't yet. You just needed to cook a little longer. Put some sawdust on top to insulate it might help, then you can stir it in for flux when it's all fully melted.

[geargnasher]

Wheel weight metal can have several different contaminations, including calcium and zinc.

Calcium can form an intermetallic bond with antimony and make "oatmeal" in the upper portions of the melt. The best solution for that is to use sawdust or wood shavings for flux, as it chars and burns it will absorb the calcium and a whole lot of other stuff you don't want in your melt, but leave everything you DO want behind, in a nice, de-oxidized (reduced) form.

Zinc will make a clean, non-miscible layer on top, like oil on water. I'm not sure this is your problem, didn't see it when it was all melted in the pot and it's tough to tell from the hardened residue. Zinc will mix with the lead and other metals in small percentage, but much of this depends on heat. Even at very hot temps only a few percent zinc is all it will absorb, which is enough to ruin the casting qualities of the metal. If it looks like a little oil floating on water, that means the lead alloy has reached its zinc-saturation point for the temperature it's at and the rest won't go in, but floats as it has a lower specific gravity. Zinc is difficult to remove, but lowering the temperature and skimming will get a lot of it, and sawdust helps too. Always stir vigorously when adding sawdust to get as much of the metal as you can directly exposed to the sawdust. After you get as much of it as you can out, using sulfur crystals and mixing it in when the lead is "grainy" or like brown sugar (almost solid).

I don't know what you used for flux, but sawdust is really the best thing you can use for lots of reasons. Use lots of it, let it smolder and mix the lead through it over and over, when it's a grey ash, skim it off and do it again. Light the smoke from the sawdust if you can, that helps reduce the oxides of tin, antimony, and lead back into the melt.

There are two ways you can remove tin from the alloy, so don't let anyone tell you it isn't possible: You can heat the alloy above 750 degrees F and keep skimming the dross off (it will have a much higher percentage of tin in oxide form in it than the molten alloy will), and you can use borate flux. Borates, like Marvellux, will soak up lots of impurities you don't want in your melt, but will also absorb tin oxide like crazy. If you use such a thing to flux your alloy, "reduce" all the oxides first with sawdust or grease/wax/oil, since the borate glass won't absorb tin as an element, only the oxide form.

Gear

[Sloffie]

Today I threw everything back into the pot and let it melt. Also chucked the "dross" back in.

I let it heat up pretty good and I waited and waited and waited but the silver sludge did not melt into the melt. It kept floating on top. I even cranked the heat up to full.

http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/Sludge.jpg

I was really puzzled as the lead was getting very hot and there was no change. The weird thing is I did not have any saw dust at hand. Usually the whole shop is full of the stuff, but I had the luck that it was cleaned recently. ;)
So I grabbed a piece of pine cut off and stirred the melt with it. All of a sudden the sludge became gray dust and the lead and other metals mixed back in. Scooped off the dross and fluxed again using the stick. Worked like a charm. It formed a nice layer of carbon dust on top which later turned orange.
Also my ingots look very nice now since I was more patient. ;)

So far I only have a Lyman .50cal MAXI Ball mold, still waiting for my LEE mold for the .303. So I tested the WW alloy by casting a few MAXI's. They will go back into the pot as they will not work with the Muzzle Loader. I must say I am pretty chuffed with how they came out:

http://i199.photobucket.com/albums/aa65/Mr_schark/Casting/MAxiHardCast.jpg

Oh yes and thank you for all the advice, was really helpful!

[Rattlesnake Charlie]

Once again, the advice freely given on CastBoolits proves invaluable.

[geargnasher]

It was probably just oxides then if the carbon from the stick took care of it. Oxide scum can get coated with molten metal and sort of encapsulated, it's impossible to break it up without chemically reverting the oxides back to elemental metal. Once you introduce a sacrificial reducant like the stick or sawdust, the oxygen lets go and the stuff melts right back in leaving only ash residue. Glad that fixed it, it was definetely not zinc!

Gear

[Defcon-One]

You are learning fast!

Nice looking bullets and a nice new Avatar, too!

Enjoy,

DC-1

[Sloffie]

Thanks! I was very relieved when everything melted back in. I do not have experience with hard lead, only pure lead. That is why I was confused.
On my first avatar, that was one of the very first bullets that I cast years ago. Should have taken a photo of my more recent casts, but they are full of lube.

[Springfield]

Until you get a thermometer, my rule of thumb is if the sawdust doesn't burn easily when spread on top then the lead is not hot enough.