Smelting And Fluxing

[joeb33050]

I don't flux much, don't see the need. When I get some sludgy stuff on top of the pot, I flux, it burns, the sludge turns into a dense powder, I scrape it off and throw it away Very rarely.
Last week I smelted one joint compound pail of WW down into muffin tin ingots. Used a 1000 watt hot plate ($5 at Salvation Army), a SS cooking pot with lid ($6.50 SA), a skimmer and a big kitchen ladle ($1 each SA).
I just realized that I didn't use any flux for the entire process. None. Not a smidgn. Zero. No flux atall.
Maybe we're over-fluxing!!
joe b.

[VTDW]

Joe,

You smelt almost exactly the way I do and with the same equipment. At times I like to throw a bit of cedar shavings on the melt for the aroma. I do scrape the side of the pot quite a bit and it seems to work for me. No...it does work for me.

Dave

[montana_charlie]

I just realized that I didn't use any flux for the entire process. None. Not a smidgn. Zero. No flux atall.
Maybe we're over-fluxing!!
Maybe you're right...and maybe we should stop using the word 'flux', too.

I don't 'smelt', so I don't get involved with 'dirty' loads of metal. But, I really can't see how 'flux' is required to make sand, clips, and valve caps come the the surface of hot wheelweights. Their density (or lack of it) will cause that to happen.
Seems like 'stirring' is sufficient for that stage of the process.

With the hardware floating on the surface, 'skimming' will get the bulk of it out, and (perhaps) a 'touch of carbon' at the end (for the oxides) is plenty.

While I don't 'smelt', I do 'blend' clean metals together to get enough weight to then 'alloy' with tin for my actual casting metal.
Some of the lead that I blend has that grey coat of oxidation on it...and that will get 'reduced' just before the pot is emptied into ingot moulds.

If we used the term 'reduce' instead of 'flux', it might be easier to remember the actual purpose of the procedure. Being more aware of the 'purpose' would make it a lot more clear when the desired effect was being observed...and when enough of it had been done.
CM

[Lead melter]

Here's a question that has run through my mind several times. If we start with relatively clean alloy, raise it to casting temperature, then flux, stir, or whatever, to bring the impurities to the top, what would be wrong with leaving those impurities there?
It seems they would act as somewhat of a "seal" to keep the alloy out of contact with oxygen, thereby reducing the amount of oxidized tin that we would skim off as dross.
Add the sprues back into the pot, and there would be a slight gap in our seal, but would that would be easily sealed again by stirring, scraping, etc.
Just a thought.

[opentop]

Some times it is necessary to flux. I learned this by smelting down some lead pipe. The lead was getting kind of stringy and sticking to the ladle real bad. I threw in some bees wax and the lead started flowing like water.

[montana_charlie]

If we start with relatively clean alloy,...then... bring the impurities to the top, what would be wrong with leaving those impurities there?
What would be the nature of those 'impurities'?
If you begin with cleaned WW metal, nothing inside is undesirable...so would not be considered an impurity. Further, (I think) we all understand that none of those ingredients are going to 'seperate out' of the alloy, so anything appearing on the top must be oxides of the metals in the alloy.

It seems they would act as somewhat of a "seal" to keep the alloy out of contact with oxygen, thereby reducing the amount of oxidized tin that we would skim off as dross.
In one of those highly technical papers you can find when you search hard enough...and have the patience to read the whole thing...the information indicated that as the amount of tin oxide (compared to lead oxide) increased, it caused tin to oxidize at an increasingly faster rate than the lead.

I think that a layer of 'something' on the alloy is a good idea...I just don't think that 'oxidation' is what that layer needs to be made of.

Finally, if reduction will cause those oxides to return to their original state, there is no 'dross' to be removed (from originally clean metal)...just the powder left from the reduction process.

CM

[Blackhawk Convertable]

I smelt exactly the same way you do except I use 2 electric elements. I use a small handful of saw dust to flux. Other than that, I use a two hand method for making ingots. With one hand I skim the surface with a puddy knife and with the other I dip my ladle. Skim and dip, skim and dip until the pot is almost empty. Add more WW's to the pan and start over again. Gotta agree with you about over fluxing, don't see much impurities in my melt.

[longbow]

I think there is a general misunderstanding of the terms being used.

Smelting is not what bullet casters do. Smelting is reduction of ore to separate a metal from oxides. We simply melt and alloy in bullet casting.

http://www.merriam-webster.com/cgi-bin/dictionary?book=Dictionary&va=smelting
http://en.wikipedia.org/wiki/Smelting
http://www.businessdictionary.com/definition/smelting.html
http://encyclopedia2.thefreedictionary.com/smelter

Fluxing is a term used in smelting, welding, brazing and soldering and has slightly different meanings. Flux in smelting results in a liquid molten slag in a blast furnace (we don't smelt) while fluxing referring to soldering and brazing operations is "cleaning" by removal of some oxides and protection from further oxidation.

http://www.yourdictionary.com/flux
http://en.wikipedia.org/wiki/Flux_(metallurgy)
http://www.newton.dep.anl.gov/askasci/chem03/chem03278.htm
http://www.kester.com/en-us/leadfree/flux.aspx

I do not "flux" very often when casting and usually only when I see a metallic film forming on the surface of the lead. I have never verified this but I was told that tin tends to separate (if present) and this is the stringy metallic film and "fluxing" stirs it back into the melt leaving only the dry dross after. I will check with the process engineer at work on this.

What I do know is that I ladle cast from an open pot and when I get stringy metallic film I drop a piece of wax or pour a small amount of oil on top of the melt, light it and stirr - the film goes away and I skim the dry dross off the surface. This is a cleaning process not a reducing process.

This dry dross is very bad stuff so don't breathe in the dust it is largely lead oxides.

Longbow

[xr650]

The WW that I, process?[smilie=1:
I stir the pot before I skim off any clips. It seems to me that the oils on the WW would flux.
I flux after skimming off the trash. I have been wondering if this is necessary.

[454PB]

There is usually sufficient grease and other carbon containing junk on dirty wheelweights to do a fine job of fluxing.

When I use a bottom pour (98% of my casting) I leave the dross on the surface. It does act as an oxygen barrier, and I don't remove the dross until I'm done casting or the pot is nearly empty.

[joeb33050]

I think there is a general misunderstanding of the terms being used.

Smelting is not what bullet casters do. Smelting is reduction of ore to separate a metal from oxides. We simply melt and alloy in bullet casting.

http://www.merriam-webster.com/cgi-bin/dictionary?book=Dictionary&va=smelting
http://en.wikipedia.org/wiki/Smelting
http://www.businessdictionary.com/definition/smelting.html
http://encyclopedia2.thefreedictionary.com/smelter

Fluxing is a term used in smelting, welding, brazing and soldering and has slightly different meanings. Flux in smelting results in a liquid molten slag in a blast furnace (we don't smelt) while fluxing referring to soldering and brazing operations is "cleaning" by removal of some oxides and protection from further oxidation.

http://www.yourdictionary.com/flux
http://en.wikipedia.org/wiki/Flux_(metallurgy)
http://www.newton.dep.anl.gov/askasci/chem03/chem03278.htm
http://www.kester.com/en-us/leadfree/flux.aspx

I do not "flux" very often when casting and usually only when I see a metallic film forming on the surface of the lead. I have never verified this but I was told that tin tends to separate (if present) and this is the stringy metallic film and "fluxing" stirs it back into the melt leaving only the dry dross after. I will check with the process engineer at work on this.

What I do know is that I ladle cast from an open pot and when I get stringy metallic film I drop a piece of wax or pour a small amount of oil on top of the melt, light it and stirr - the film goes away and I skim the dry dross off the surface. This is a cleaning process not a reducing process.

This dry dross is very bad stuff so don't breathe in the dust it is largely lead oxides.

Longbow

We call it "smelting" and "fluxing", and have been for a long while. Your references don't accurately describe the word meanings. And, we-the fluxing smelters, have known for many years that the tin doesn't separate or segregate from the alloy.
joe b.

[DLCTEX]

Universally accepted terms are institutions, very hard to change, and as long as we know what is referred to, harmless. DALE

[swiss 96/11]

I use a burner from a hot water heater that i trash picked. You have to make sure the hot water heater was used with PROPANE or change the orfice in it to a Propane one.A orfice at a gas dealer only cost a couple of bucks. Cut the bottom 4" off a grease drum,I put a heavy walkway grating on top and use a SA Cast iron (large) pot.Melt WW,give a good stir,skim off metal clips,then cast into cup cake tins.good old rusty ones from SA or garage sales. Able to melt a 5-gallon bucket at one time and get a fairley consistant melt. NO fluxing,However i may try fluxing next time to see if it helps.

[Molly]

Hey fellows,

Lookit at what I found while stumbling around on the internet:

"Abstract
The invention regards a procedure and a device to deoxidize metal melts by using a reducing agent which is introduced into the metal melt. In order to be able to produce metal melts with the lowest possible oxygen contents in the simplest and most economical manner, it has been determined to use alcohol, molasses or lignin, or a mixture of these materials, as reducing agents. "

I really wouldn't recomend alcohol, due to the possibility of explosions. Lignin is what holds wood fibers together, so maybe the sawdust suggestion has some merit. But the molasses bit throws me! I've never heard that one. Talk about a sweet casting situation ....
Molly

[VTDW]

Universally accepted terms are institutions, very hard to change, and as long as we know what is referred to, harmless. DALE

:drinks: That is sooo correct. We make boolits and I shoot hawgs.:-D

Dave

[longbow]

You can call it what you want.

I checked with the process engineer at work and the word is pretty much what the links above say - fluxing is the way molten slags are modified in a smelting process so they flow and can be tapped off the melt.

When you "flux" while casting boolits you are adding a cleaning agent that lowers the surface tension of the molten metal and allows the molten metallics to flow out of the dross leaving a dry dross on top. Exactly what joeb33050 said in his original post.

If you don't flux you will simply wind up throwing away some alloy in the dross. You may also wind up with small amounts of dross entrained in your melt but no big deal when pouring ingots. Maybe a little more important when casting boolits. Fluxing cleans and degasses.

Also, you are right about the tin. I simply said I was told (by a gunsmith) many years ago that the stringy metallic in the dross was tin. I flux to stir the stringy stuff back into the melt as you all do.

Probably the most important thing to remember is that the dry dross is bad stuff so be careful when handling it - don't breathe it and wash your hands after handling it especially if you already have concerns about blood lead level.

[Sherlok]

Personally, I'm of the old school of fluxing often (I use a candle) to keep the metals from seperating. I think it keeps the alloy more consistant during the casting session.

Has worked for me.

Sherlok