fluxing while smelting... how important is it?

[par0thead151]

like the title says, how important is it to use wax, or wood chips to flux while smelting?
i always stir the lead until the clips and crud are separate from the melted lead, and everything is mixed in well. i use a steel rod to mix the clips and weights till it is melted. is it essential to flux while smelting?
i use paraffin wax to flux in my bottom pour furnace while casting though.
should i add fluxing to the smelting process?
thanks

[JSnover]

Skimming gets out the stuff you can see. Fluxing gets the stuff you can't see. Mostly oxides. I flux during either process.

[Shiloh]

Wheel Weights seem to have residual oil on them that acts as a flux. Either from the road or from handling in the tire shop. You will hurt nothing by adding flux when smelting. I would wait until the bulk of the obvious garbage is removed though. From what I have seen, smelting in a iron dutch oven, there can be quite a bit of clips, valve stems, washers and other stuff that comes to the top.

Same with range scrap. Lots of jackets, wads, rocks, ect.. I found some bean bag type shotgun round projectiles in a canvas pouch once. Found a corroded live round also. That would definitely would be a surprise when smelting.

Shiloh

[Hardcast416taylor]

The following is what I do when I render the ww and other scrap lead down. Obviously I use a seperate pot to smelt the stuff in. I make sure all weights are melted by pushing them around with an old hammer handle. I remove the clips with a 7" long 1" dia. magnet, I clean them off the mag with a leather glove. Now I add some candle wax and do a flux procedure. I now ingot the lead, I will flux as usual when I make a casting session and have very little crud to remove. I quit using marvaflux years ago and went back to my original fluxing material - candle wax and or parafin. As I said at the start, "This is how I do it". :castmine: Robert

[blackthorn]

Once the initial bunch of crap is skimmed off I stir the melt with a VERY DRY piece of 1x2 lumber. I also use a wooden stick to flux the casting pot if I think it needs it. Works for me!

[mtgrs737]

Throwing in a handful of saw dust from your favorite smelling hardwood will make sure you flux during the smelting process. Just make sure the sawdust is dry.

[docone31]

I melt my start in a cast iron pot. I also use the kitchen stove when the wife is not here.
I skim whatever solid is on the top.
Once in ingots, when I cast, I keep a layer of Kitty Litter on top of the casting pot.
With the Kitty litter on top, it gradually gets finer and finer, and more and more crap attaches to it. I can also toss sprues and other rejects, ingots, etc, directly on top of the Litter. It acts like a buffer in case there is moisture present.
I have done this since day one.
Works pretty simply.
If I keep skimming off the oxides, pretty soon I have no melt left.

[monadnock#5]

Liquid lead has surface tension. The melt rounds over at the edges. As you're smelting, oxides and other stuff at the edges get rolled into the side of the pot and submerged. Fluxing helps reduce the surface tension, but it's the scraping and stirring at the side and bottom of the pot that removes most of the crud.

A stainless steel pot for smelting is a very good thing. You'll still find crud on the side and bottom when empty, but it's much easier to scrape out. It gives you the opportunity to start fresh with each new melt. As opposed to cast iron which collects a fresh new layer of dross with each melt.

[jdgabbard]

I melt my start in a cast iron pot. I also use the kitchen stove when the wife is not here.

docone, I'd never bash what another member does. But I must ask why you would contaminate your home like that? Do you not worry about exposure?:-?

[Andy_P]

I don't add flux while smelting - there's enough junk in there to act as flux that it's not required. I do flux at the casting stage each time I add ingots.

[Bret4207]

docone, I'd never bash what another member does. But I must ask why you would contaminate your home like that? Do you not worry about exposure?:-?

To get airborne lead exposure the alloy would have to be up over 1100 degree's F and that ain't happening unless you TRY to do it. He's in far greater danger from SWMBO than the lead pot. Nothing like a few drops of lead alloy on the floor to destroy your domestic bliss...

[Linstrum]

A couple of things about re-claiming scrap lead alloy like wheel weights:

The main thing about using a reducing-type cleaning agent like wax, sawdust, etc, is to RECOVER the oxidized minor alloying constituents in with the lead. Lead metal is a bit more inert than tin and antimony, and due mostly to what is called the Electromotive Series of the Elements, when they are in contact with lead, the tin and antimony will for the greater part oxidize before the lead does because they are more reactive. In essence, if a bit of lead oxidizes, the lead oxide is immediately attacked by the elemental tin and antimony and the tin and antimony accept the oxygen from the lead oxide to reduce it back to the elemental lead form, and in doing so the tin and antimony become oxidized and stay oxidized. On top of that, tin and antimony quite readily oxidize when hot and in contact with the oxygen in the air. If a FLUX is used at this point it will REMOVE the tin oxide and antimony oxide floating on top of the alloy in the melting pot and deplete the alloy. To prevent depleting the desirable tin and antimony alloying constituents, a REDUCING AGENT is used, like wax, sawdust, sugar, polyethylene plastic sandwich baggies, powdered charcoal, straight non-detergent motor oil, vegetable oil, etc. The reducing agent will attack the tin oxide and antimony oxide and reduce them back to their elemental forms by removing the oxygen combined with them, and they will immediately dissolve back into the alloy where they belong. This is a good thing because it keeps from depleting them in your alloy.

The best material for treating scrap lead alloy is pine tree pitch (rosin) since it has both reducing agent (smelting) properties as well as fluxing properties and it will readily reduce the tin oxide and antimony oxide back to their elemental forms plus remove unwanted dirt without removing the tin and antimony, unlike a straight fluxing agent such as MOLTEN borax. But if you don't have access to a pine forest to get pitch for free don't worry about it, just use sawdust, wax, or whatever, since they work pretty darned good, too. By the way, don't bother using borax for boolit casting alloys, the melting pot temperature is way, way too low for it to work since it must be molten at a bright red heat to have an adequate effect.

A magnet is a pretty good idea to get the clips and other iron debris out. If you have a rare earth magnet like a cobalt-samarium magnet, it might be a good idea to stick it onto an iron spatula where it won't get too hot since high heat could possibly degrade the magnetic strength after awhile and those super-powerful magnets are pretty expensive. I have one I use to trick kids with, I hold it clenched in my fist out of sight and pick up nails on my knuckles.

Like Bret4227 already mentioned, pure lead metal has to be pretty darned hot to generate any lead vapor, which is why boolit casting is a pretty safe activity as far as breathing poisonous lead fumes. But - what will get you is the antimony oxide dust that is always around in small amounts no matter what you do to keep it reduced back into the alloy like I just said above. For those of you who have not had chemistry, antimony is right below arsenic in the Group 15 elements (nitrogen, phosphorus, arsenic, antimony, and bismuth) and resembles arsenic a great deal in its chemical properties, including being darned poisonous in rather tiny amounts! So, be careful about breathing or otherwise accidentally ingesting any dust from the dross.

Have fun!

rl537

[par0thead151]

To get airborne lead exposure the alloy would have to be up over 1100 degree's F and that ain't happening unless you TRY to do it. He's in far greater danger from SWMBO than the lead pot. Nothing like a few drops of lead alloy on the floor to destroy your domestic bliss...

how do you deal with the smell and fumes?
when i smelt wheel weights there is a lot of smoke and it REEKS. my truck stinks of lead wheel weight smelt for a week after i transport the buckets of wheel weights and clips back home(i smelt off site)

[JSnover]

If you can't do it out in the open, use a good fan to ventilate. I've smoked myself out a few times, going too heavy on the flux, temp wasn't high enough to light it off, etc.

[weakhand luke]

I like Marvelux. Why does it get such a bad rap?

[dragonrider]

Marvelux attracks moisture when cool and will rust your pot. I wont have it in my shop. I use sawdust for flux when smelting and I stir with a DRY STICK, I never use a petroleum distillate of any kind to flux with. Important to get lead as clean as possible when smelting, this keeps your casting pot clean and sweet smelling. Dripping is kept to a minimum.

[454PB]

I've used Marvelux for 30 years in the same pot(s), and none of them have been damaged by rust yet. All my pots have a coat of dross from use, which seems to prevent rusting.

It is hygroscopic and attracts moisture, so don't dip a cold stirring device or dipper previously used with Marvelux into molten mix. That's just plain good sense no matter what you use for fluxing.

[Bret4207]

how do you deal with the smell and fumes?
when i smelt wheel weights there is a lot of smoke and it REEKS. my truck stinks of lead wheel weight smelt for a week after i transport the buckets of wheel weights and clips back home(i smelt off site)

Thats the domestic bliss end I was talking about. I do my smelting out doors and casting in my barn. No way honey bunch would endorse the idea of my smelting indoors!