Lead fluxing?

[firestick]

Help me understand what fluxing of lead is and what is taking place in this process. Is there a minimum temp that must be reached in order for it to be effective? Have always done it using beeswax or alox but never understood what actually was happening other than it removed impurities.

 

[Nazgul58]

I have cast many types of lead bullets over the last 50 years. For pure lead bullets, when the lead is melted, you want to skim off anything that floats. This helps remove things you don't want incorporated back into the melt.
When the melt is up to temperature, with pure lead it will be slightly higher. Say around 700 degrees. Then you flux. You can use anything that has wax/fat/resin in it. Everything from bacon grease, crayons, beeswax, candles, pine sawdust or a commercial flux. I would not spend any money on flux as materials are available free around your house. Stirring the melt as it is added.
When the flux burns off, it can be ignited to reduce the smoke. Clean anything off the top that floats and you should be good to go.
I do not know the chemical action flux has but it does make casting much easier.

Don

 

[mooman76]

Just about anything that burns can be used. Many people like sawdust, in particular, pine. Some others just stir with a wooded spoon. I don't know exactly what happens but stir it in a crud floats to the top, skim it off. That said I usually flux initially when I smelt but rarely there after. Do it too much and you are just removing good lead.

 

[Jaeger]

Fellas.....fellas! You mean we don't have anyone on this forum who is an educated chemist or physicist and can tell us exactly what happens when we flux a pot of lead? C'mon....it's not MAGIC! If we don't get an answer, then we are stuck in the Dark Ages doing magic.....

 

[Pete G]

Fellas.....fellas! You mean we don't have anyone on this forum who is an educated chemist or physicist and can tell us exactly what happens when we flux a pot of lead? C'mon....it's not MAGIC! If we don't get an answer, then we are stuck in the Dark Ages doing magic.....

Perhaps it IS magic...

 

[nkbj]

Black powder is magic so why not lead?

 

[Griz44Mag]

As it was explained to me so many years ago:
Once heated and released - the carbon atoms readily combine with almost anything else that is in the lead in the way of impurities.
Then those impurities will float in the lead where they are easily removed by skimming.

 

[George]

Fellas.....fellas! You mean we don't have anyone on this forum who is an educated chemist or physicist and can tell us exactly what happens when we flux a pot of lead? C'mon....it's not MAGIC! If we don't get an answer, then we are stuck in the Dark Ages doing magic.....

A little white magic....

http://www.lasc.us/FryxellFluxing.htm
Spence

 

[bubba.50]

You can use just about anything lighter than the lead itself. A lot of people use kitty litter, unused of course. LOL

and some people just stir it with one of those freebie paint paddles from the hardware store.

 

[mooman76]

Kitty litter doesn't work as flux. It's used on bottom pour pots. Cuts down on oxidation.

 

[Jaeger]

And there we have it! It's all science!

 

[Ames]

As it was explained to me so many years ago:
Once heated and released - the carbon atoms readily combine with almost anything else that is in the lead in the way of impurities.
Then those impurities will float in the lead where they are easily removed by skimming.

Skimming................or just shoot it out. Unless you melted garbage or tin, don't overthink the flux. Toss a little wax or sawdust into the pot, skim it and move on. Go shoot.
The science would give half of us headaches.

 

[Zonie]

As it was explained to me so many years ago:
Once heated and released - the carbon atoms readily combine with almost anything else that is in the lead in the way of impurities.
Then those impurities will float in the lead where they are easily removed by skimming.

From what I've read about fluxing, you are right about the carbon atoms that result from heating the fluxing material.

They will combine with tin oxide, removing the oxygen and allowing the tin to return to the lead.

If that's true, and we are using a lead/tin alloy, fluxing can help maintain the lead/tin ratio in the mix but since most of us want to cast pure lead, fluxing the mix would be going in the wrong direction. Removing the tin could be good for what we want to do.

I usually flux the molten lead but I think probably the best thing it does if to force me to skim the junk that has floated to the top of the pot. There is no doubt that that light weight stuff that floats to the top isn't good for making quality castings.

 

[Griz44Mag]

From what I've read about fluxing, you are right about the carbon atoms that result from heating the fluxing material.

They will combine with tin oxide, removing the oxygen and allowing the tin to return to the lead.

If that's true, and we are using a lead/tin alloy, fluxing can help maintain the lead/tin ratio in the mix but since most of us want to cast pure lead, fluxing the mix would be going in the wrong direction. Removing the tin could be good for what we want to do.

I usually flux the molten lead but I think probably the best thing it does if to force me to skim the junk that has floated to the top of the pot. There is no doubt that that light weight stuff that floats to the top isn't good for making quality castings.

Agreed completely.
I start with pure lead and especially if I am casting conicals and doubly if I am casting hollow bases (minnies) or hollow points I add a few ounces of tin to mix. It makes a big difference in getting complex molds to cast smoothly and wrinkle free. It also lowers the melting point a few 10's of degrees to help keep complex molds from making bullets with occlusions or wrinkles. I have been casting for more than 5 decades and still don't consider myself an expert, but when I concentrate on what I am doing - I can make some mighty purty boolits....

 

[Griz44Mag]

And as a footnote, adding a little tin does not effect the hardness to any measurable degree in the small amounts you need to add to get a great shiny cast boolit.

 

[Jaeger]

Skimming................or just shoot it out. Unless you melted garbage or tin, don't overthink the flux. Toss a little wax or sawdust into the pot, skim it and move on. Go shoot.
The science would give half of us headaches.

I agree with this. I often just do a bit of stirring (use an old silver spoon with a sharp edge) and then just skim off what floats to the top. The lead is pretty clean after doing this.

 

[firestick]

Thanks for the comments. I figured there must be a chemical process of some sort that caused the impurities to surface with the normal dross. I was processing scrap lead and pouring a muffin tin to be melted later for casting. Don't know why but it seems even softer than the raw scrap. Scratches VERY easy with whats left of my thumbnail.

 

[Ames]

Could give it a hardness test, before and after.

 

[1853enfield]

i have been casting bullets for almost 50 years both for fixed and muzzle loaders.. be careful with the sawdust unless you really want to spend a lot of time skimming it off. i would never use it even if i was using bottom pour. i have found it is good to flux twice once with bees wax and another with a something like marxelux a commerical fluxing compound. the purpose is to remove impurities and to put metals into a solution. i try to keep it simple and having to remove kitty litter or sawdust is a bit more work than i want. for real good information slip over to the cast bullet association forum and do a search. I have learned a lot for sure you dont want to wind up putting a live primer into the melt. and also tipping over a pot with 20 lbs of melted lead in it. Not that i know anyone who has done either of those things.... but i heard once about someone who managed to do both.

 

[Carl in France]

I use a bottom pour pot and always flux and skim off the floating rubbish.
But....as it is a bottom pour is there any point?