Newby Question on Fluxing

[TimBoothe]

First off, thanks to everyone that has contributed to this site...such a valuable resource for the beginners like myself.

I'm in the beginning stages of learning this art and am a little confused on fluxing. Upon reading the advice of many on this board I purchased a copy of the Lyman Cast Bullet Handbook 3rd Edition. On pg. #57 "Melting and Fluxing Bullet Metal" it states "As the metal melts, a gray scum will rise to the surface, contrasting sharply with the silver brightness of the molten lead. DO NOT REMOVE THIS SCUM. This contains tin, the most valuable component of the bullet metal." It talks a bit about fluxing materials, how to stir them in the pot and then goes on to say "Metal that has been properly fluxed will leave the surface almost mirror bright and flecked with small particles of black and brown impurities. Skim off and discard these impurities."

Now for the un-initiated such as myself, the way that I interpret this is as follows: Once the metal has melted, sprinkle my sawdust used as flux and the only thing that should be left on the surface of the melt will be these "flecks of small particles of black and brown impurities".

Well...that ain't how it's turned out so far. I melted a 15 pd block of lead in a cast iron skillet over a burner at around 650-700. Once the melt was completed, I sprinkled about half a hand full of sawdust over it. It immediately turned black..smoked up my shop pretty good. I then took a small piece of pine that I used as a stir stick and stirred it in. I'd push the little embers under and they'd pop right back up. I kept doing this until they were all black and essentially lifeless if you will. I had a heck of a lot more stuff on top than just some small flecks. I added some more sawdust and repeated the procedure. Ended up with more dross is all. After this second treatment with sawdust I went ahead and skimmed the surface.

I'm scared that I removed tin from the mixture. I mean after reading what the Lyman book says..""Metal that has been properly fluxed will leave the surface almost mirror bright and flecked with small particles of black and brown impurities. Skim off and discard these impurities." It sounds to me like I might have goofed.

I guess that's my question, did I goof or did I do it proper? Now if I did this proper....I've read on here that you can't flux too much. Should I just continue to repeat the process until I don't get anymore dross?

I'll have tons more questions throughout this whole process so ya'll bear with me.

Thank you in advance,
TimBoothe

[mooman76]

When you flux you are going to remove some of the tin too. There's no way around it, just don't get carried away. You want the stuff that looks rough like sand. Skim that off. I don't continually flux. When I get stuff on top I just move it around out of the way with my ladle and then after I get allot gathered, I will remove it. I hope this makes since to you.

[leadhead 500]

I never used sawdust before to flux with.But from my experiance the best flux to use is pine sap (pitch).Drop a lump about the size of a pea into the lead and ignite it with a match and stir the lead realy well and then discard the impurities.

[FN in MT]

#1.....I'm far from an EXPERT here, but have been casting off and on...for a bunch of years.

I've ALWAYS used parafin or candle wax for a flux. In my 20# pot I drop a piece the size of a .45 slug into the pot and immediately hit it with a wooden match. The match starts the smoke from the parafin on fire, cutting out 90% of the smoke. Mix it in until the flame is out and thats IT.

When fluxing wheelweights or plumbers lead that I'm mixing into my alloy one needs to flux pretty good as theres lots of crap in those WW's. I'll flux with a fairly large hunk of candle or parafin allowing a minute or so before the flame goes out.

Personally I'd try some candle wax and forget the sawdust.

FN in MT

[454PB]

No matter what you use for a flux, the melt is going to continue to produce oxides that float to the surface. You could flux every 5 minutes, and still find more oxides (dross) rising to the surface. Over the years, I've learned to flux well, then leave the dross on the surface. It acts as an oxygen barrier (as does cat litter) to reduce the reformation of oxides. This is one of the reasons I prefer bottom draw casting to dipper casting. Dipper casting is constantly exposing more surface area for oxidation.

[DLCTEX]

I think half a handfull of sawdust is too much. I usually flux with a dry wooden stick, stirring and scraing the sides and bottom of the pot, the skimming. the amount of wood consumed is minimal. I would guess half a spoonful would be more than enough.

[NoDakJak]

For thirty five years I used candles, parrifin or bees wax as a flux. About a year and a half ago I read on this forum about using sawdust as a flux. It works great. I have tried using just a little and also a lot. I like a lot! I add a large handful and stir in well. Then I just let it float on the surface. It acts as a barrier to reduce oxidation and also acts as a very effective insulation. This keeps the melt at a more even temperature, producing better boolits and reducing the cycling (wear and tear) of the thermostat. You need good air movement though as the stuff smoulders and smokes for a while. When I need to add lead I skim it and flux anew! Works great for me. Neil

[runfiverun]

i usually stir the jebus outta the pot and get a big ball of oxides and such on the top first then flux,skim and pour. i like to have a barrier on top also.
but i like marvelux,as it just forms a barrier.

[TimBoothe]

Thanks for the replies fellas. It sounds as though I'm doing it correctly.

TimBoothe

[GabbyM]

If you can't find any wax candles and such go in the kitchen when the wifes not looking and snag a bit of lard, Crisco or cooking oil.

When melting down wheel weights outside I've been known to poor copious amounts of used motor oil on top then light it off.

[jnovotny]

I just used jointer chips of white pine mixed in some transmission fluid(ATF), worked pretty good.

[Randall]

I use any old grease to flux with,usually hamburger I spoon off into an old can. Bacon generally gets used to cook with.