Fluxing Questions

[Castaway]

Can someone explain fluxing to me?  I've cast many thousands of bullets since I started 12 years ago.  Yes, I flux and yes I skim off the crud that gathers at the top of the melt.  What is happening when I add my pea sized piece of candle wax and stir it in, other than bad stuff floating at the top?  Don't misunderstand, I know I have to do it and I know how to do it, I just want an expaination on why and how a fluxing agent brings the gunk up.  And by the way, what happens to any tin you have in the melt when you repeatedly flux in the same pot of lead?

[mugs]

Look at www.lasc.us and articles by Glen E. Fryxell. Good article about fluxing.
Mugs

[quickdtoo]

Maybe this will help explain the process...

Fluxing: Why fluxing is necessary, what effect it has on the alloy, and how to do it.

Clean metal casts most easily and well. Fluxing is the process whereby we clean our molten metal. The 'dross' (slag and other contaminants) is in part oxides of the metal, and unoxidized metal in the form of very small spheres (shot). The 'shotted metal' is held in that form by a thin layer of oxides and contaminants, the surface tension of the oxide layer prevents the shotted metal from being wetted by the molten metal. The purpose of the flux is to break down the surface tension, and allow the molten metal inside the shot to return to the main body of the metal. The loosened oxides appear to be coagulated by the flux and suspended in the flux body. This can then be skimmed off. This is the only effect that fluxing the molten alloy has. The only way fluxing can change the alloy is by returning shotted metals to the general mix. Generally, this will have little effect on the alloy's composition. Most of the dross will be in very small particles distributed throughout the pot. The flux acts almost entirely on the surface though-which is why it is necessary to stir the metal thoroughly when fluxing.

Once the lead is melted, drop in a pea sized piece of wax or the appropriate amount (per instructions) of a commercial flux. If it smokes, light the smoke with a match. Stir the lead, being sure to scrape the sides and bottom of the pot. After a bit, a bunch of brown junk will rise to the top of the molten lead. This is the dross -use your mixing spoon to remove it and place it in a safe container. Repeat the cycle two or three times.

It is fairly common to toss the dross removed when fluxing into a coffee can. KEEP THAT STUFF DRY. Under the right conditions, certain contaminants in the dross can release stibine gas, which is toxic. Recently, I have gone to using a NEW 1 gallon paint can. Cost two bucks at a paint store, but now I have no excuse to forget to cover the dross can. I figure the can will hold several years of dross at the current rate I am generating it. Some years back, the NRA set up a deal with various lead refineries to take dross so it would be recycled. Contact the NRA for information on this.

http://members.aol.com/illinewek/faqs/casting.htm