Fluxing confusion

[uglysteve]

Hello,

I've been reading "From ingot to target" and am not sure how the fluxing thing works.
I've seen some videos where guys are melting wheel weights and just add a small tea candle's worth of wax to the pot and then scrape off the top. That's it. According to the book, however, that may not be enough. The book says that using sawdust is a great way to prevent oxidation. This is where i'm confused. How do you all flux from start to finish?

This is how I think it goes:
-Melt wheel weights or range lead in a cast iron pot on a turkey fryer burner.
-Add some paraffin wax to flux the mix.
-scrape off the waste on the top.
-Make ingots
-Melt ingots in bottom poor pot
-Add 1 heaping tablespoon of sawdust to the mix and stir it in.
-Make bullets

Am I right?

Please clarify or point me to a more definitive source of information on this subject.

Steve

[USAFrox]

Read this thread. It should answer all your questions.

http://castboolits.gunloads.com/showthread.php?212084-Flux-question

[Defcon-One]

This is how I know it goes:

- Melt wheel weights or range lead in a cast iron pot on any burner (650-700 degrees F).
- Add some sawdust (I like pine best) to flux the mix. I use about 1/4-1/2 cup for an 80 pound batch.
- Stir it vigorously for a few minutes being careful not to splash any molten lead out of the pot.
- Once the sawdust turns dark brown and is smoking, throw in a lit match to burn off the smoke and flamable parts. Keep stiring it.
- Skim off the black ashes (Charcoal) from the top. (Dispose of properly, as it is somewhat toxic!)
- Your lead will be shiny and clean, ready to cast ingots.

To cast bullets:

- Melt ingots in bottom poor pot.
- Make bullets!
- Flux again, only when/if needed.


FYI: Wax is for candles! It is not a complete fluxing agent. It reduces, but does not remove impurities or prevent oxidation! It also will leave a black film on your equipment that gets thicker and thicker over time.

[uglysteve]

Thanks for your replies. How do i know when or if it needs re-fluxing when making bullets? Also, should I leave a layer of charred sawdust/shavings on the lead while casting?

[evan price]

Fluxing your casting alloy will be different than fluxing dirty scrap to MAKE casting alloy.
When you melt down scrap there will be a lot of dirt and grease and paint and other junk.
There will also be oxididized metal.
You want to reduce those oxides back into your alloy and also remove impurities.
There are two fluxes.
Reducing fluxes- which provide carbon which has a strong affinity for oxygen, in the presence of heat this will cause lead or tin oxide to break down, the oxygen joins the carbon to make carbon oxides and the metal is back in the alloy.

There are also slag-forming fluxes, these trap contaminants and dirt and form a crust on top to make it easier to skim off the crud.

When you talk about leaving a layer on top, this is to prevent oxygen from oxidizing the surface of your hot liquid metal, and needing less reducing fluxing later. This is very useful with a bottom pour pot.

Lots of people use clean sawdust to flux with. This provides carbon and leaves an ash layer on top of the melt to keep the air away.

I flux fresh scrap melts with used motor oil. It's free and I have it around regularly. This provides carbon and burns off readily. The additives will leave a slight crust of slag. I stir the big pot with a 5-gallon-bucket paint stir stick, get them from the big home improvement stores for free if you ask. Wood has carbon, and acts as flux while you stir and scrape the crud off the sides and bottom of the pot.

Your casting pot should need only a small amount of flux. A broken bit of a crayon about as big as a lima bean is more than sufficient. I save the wood chopsticks from takeout chinese food to stir my bottom pour casting pot. Free, and carbon source.

[bangerjim]

This is not rocket science. Do not be afraid! Just to it.

Melt your lead, throw some wax in, throw anything that will burn (carbon-based) in and stir....stir...stir with a wooden stick/spoon/paint stick. Scoop out the crpola that is left.

Use wax in your bottom casting pot.........I have forever and it works perfectly.

You can loose your mind if you try and follow all the "tales of fluxing/reducing" listed on the net.

Go for it. You will learn what works and does not work for you.

bangerjim

[country gent]

Bought a bag of hicory chips at the grocery store the other day to try fluxing with will these work? they are wood chips for smoking about the size of your thumb nail or smaller. I want to try it and see how it works. Ive always used beeswax or paraffin in the past.

[Defcon-One]

In your bottom pour casting pot, a little crud on top won't hurt too much since the lead is comming out the bottom. If you see a thick grayish film building up on top that could be your Tin in oxide form. Fluxing with sawdust or wax will both work here but as I said, wax will leave a black film. You only need a little and don't stir it quite as hard as the smelting pot.

Some have trouble with dust specs or carbon from the sawdust getting into the bullets, but I never have. Also, a thin film of carbonized sawdust on top of the pot will create a barrier to prevent further oxidation! Just don't run the pot below half full before adding more alloy.

[lwknight]

Good god people!
Flux fuses dissimilar metals that would normally ignore each other.
Who is to say what is an "impurity" from a molten lead view.
Are we saying that saw dust has magic flux in it that discerns what we want in the mix and what we do not want?
Get real guys.
The saw dust and carbon might trap some impurities. And it will flux in some naturally occurring calcium from the wood.

Just maybe its the potassium hydroxide ( lye) aka: caustic in the ash that dissolves some certain metals and you just happen not to want. Most who want to lecture metallurgy don't even know just exactly what is in wood ash.

Anyway, whatever. It works out the same either way. Saw dust works great but is not required. Wax works just fine if you just so happen to have a lot of it for FREE

[geargnasher]

Good god people!
Flux fuses dissimilar metals that would normally ignore each other. In the context of soldering, or brazing, "flux" reduces the oxides and shields the surfaces from further oxidation so the metals can bond.
Who is to say what is an "impurity" from a molten lead view. Whatever makes it not want to fill a mould at reasonable casting temperatures.
Are we saying that saw dust has magic flux in it that discerns what we want in the mix and what we do not want? Actually, yes. But it isn't magic.
Get real guys.
The saw dust and carbon might trap some impurities. And it will flux in some naturally occurring calcium from the wood. Calcium in the wood?

Just maybe its the potassium hydroxide ( lye) aka: caustic in the ash that dissolves some certain metals and you just happen not to want. Lye is a sodium compound. Sodium isn't usually a contaminant in boolit metal anyway. Most who want to lecture metallurgy don't even know just exactly what is in wood ash. Now that's funny right there!

Anyway, whatever. It works out the same either way. Depends on what contaminants you happen to have in your metal. Saw dust works great but is not required. Wax works just fine if you just so happen to have a lot of it for FREE

Wax works just fine if you don't have a bunch of zinc, calcium, and aluminum in your metal, or if you and your guns don't care if you do, which really is about 99% of the people casting and shooting boolits.

Gear

[lwknight]

Commercial lye is a sodium based caustic soda.
Home made lye is weaker and less reactive that sodium hydroxide because it is potassium hydroxide that comes from wood ashes.

Most anything that grows from roots has calcium in it. Where do you think cows get it to put in milk?

[geargnasher]

That's true, but does it detract from the wood pulp's ability to clean up dirty, "contaminated" lead alloy?

Gear

[felix]

Kinda' tough to make hydroxides at home! Got a source of raw genuine (circa 100%) metals? ... felix

[geargnasher]

Certainly not as easy as establishing an environment for little yeasties to produce hydroxide compounds at home..... something like CH3CH2OH :2 drunk buddies:

Gear

[felix]

Yeah! I forgot about the most important class of hydroxides. Shame on me! ... felix

As far as I know, the chemists still have not figured out the process! Heavy duty folks have been called into the search since I first read about the secretive reaction. Perhaps UC Davis is still the forefront institution doing this cloak and dagger process. Reading their papers on the subject is quite complicated and kinda' leaves me in the dark. They have gotten close, but no cigar (circa 1985). ... felix

[lwknight]

That's true, but does it detract from the wood pulp's ability to clean up dirty, "contaminated" lead alloy?

Gear
I doubt that such a dilute concentration would matter.
I hope I did not imply that it did.

Have you ever left a bucket of ashes out that got full of rainwater?
That yellow water on top can be boiled down to a concentrate that will eat your skin off.
That's a dilute of potassium Hydroxide.

Agreed that it is not easy to get shine from wood chips.

[geargnasher]

As a matter of fact I have, but the skin I lost was on my butt from being whupped for leaving the half-full ash can outside by the workshop all summer instead of washing it out and putting it away like I was supposed to. The water standing above the ashes looked like chamomile tea, just as you described.

I also tried making lye from ashes per the wood box and drip method outlined in Foxfire, but the solution was always too weak to do much good, must have dripped too fast.

Gear

[btroj]

If my lead pot ends up with lye in it while smelting or casting I have far larger problems than a bit of impurities from wood ash.

I also don't worry about metal ions in the melt, they are easily removed by the charcoal left over after combustion. Charcoal loves ions. Now metallic Ca, that is a problem but there isn't much of that in wood.