View Full Version : Fluxing Questions

11-01-2008, 09:11 PM
What is fluxing?

How do you do it?

Why do you do it?

What effect does it have on the lead?


11-01-2008, 09:30 PM
[quote=Bullshead;421352]What is fluxing?
Fluxing is the act of washing the elements of oxides so that
the raw metals will stick to each other, hopefully with the suds
coming to the top to be skimmed off.

How do you do it?
Washing tin, lead and antimony, the usual elements for us, best be
done with a carbonized substance, like something that burns
slowly by the heat in the pot.

Why do you do it?
Stir the pot with teaspoon of motor oil, a stick, wax, etc.

What effect does it have on the lead?
Makes it a combined substance.

... felix

11-01-2008, 10:29 PM
I am not sure I completely understand fluxing, however, I do know metals will not flow or combine into a weld, braze, solder, or alloy without it.
In my opinion, fluxing in general, is an antioxidizing agent. At higher temperatures, it becomes a wetting agent.
Why do it?
In a melt, oxygen penetrates, and permeates a melt. In other words oxides form. This makes scale. Scale in time makes slag.
Essentially, oxygen with heat makes a rust. The flux, and sometimes carbon, can make an antioxidant. Lead oxides very quickly, in a melt, the surface can oxidize very quickly. Adding a flux to the surface prevents the oxides from forming, and penetrating the surface.
Lead can be melted without flux, however, flux helps the melt.
I use beeswax for flux mostly, with lead. Lead is a low temperature melt.
With silver, I use boric acid. Much different temperature range.
An example, when melting wheel weights, you have large surface area. As the melt collects and remains liquid, there is less area. The surface collects oxygen. The flux acts as a wetting agent, and oxygen barrier. In alloying, the flux helps the metals to flow together, rather than making metal layers.
I work with fluxes about every day. I still do not know why they work. I have read as many theories as there are.
Basically, fluxing makes lead casting easier. I have read Ivory Soap makes a good flux. I use beeswax because I make my lube. I have plenty. It smell good also.
Once you start casting, you will see when the oxides need fluxing. A good melt will have "plates" that form on top of the melt. The Lyman Bullet Casters Handbook shows great photos of these.
I have tried quite a few fluxes. I lately tried liquid solder flux. It has muriatic acid. I like it when I am starting my melt, but, when I pour some on when hot, it spits.
I just get better results fluxing. Borax helps some, but it is like Kitty Litter. It just collects slag, rather than fluxing.
Stirring with a wooden rod, is not fluxing. It is deoxidising. It is effective for removing loose oxides within the melt. To a large extent, too much heat, and no flux, an alloy can partially seperate during the solution stage. If the alloy is a critical mix, flux is mandatory.

11-02-2008, 12:20 AM
Fluxing is the cataliizing process process of getting lead, tin, and antimony to stick together. Without it the base metals won't adhere to each other in an alloy. As has been stated earlier in this thread, high carbon products work best in lead alloys. I use sawdust and stir it in with a teaspoon or laddle.

11-02-2008, 07:11 AM
I haven't fluxed in many years, and it has made zero difference in my bullet quality, ease of casting, etc.

John Boy
11-02-2008, 11:49 AM

11-02-2008, 12:04 PM
That video left something out, IMHO. I didn't see him stir the pot real well, nor did he scrape the sides of the pot. He only seemed to skim the surface a bit. Lots of dirt hides deeper in the melt, and also clings to the sides of the pot.
He didnīt mention the (cheaper) alternatives to store-bought flux, either.