Flux question

[MikeACP]

First I apologize for all the newbie questions. I'm almost read y to smelt. Flux?? I've read on here everything from wax to Marvelux to sawdust. Can someone explain how saw dust works? Will it flame up like wax?

[sundog]

If you are rendering WWs, then even the old valve stems and tire labels are good flux. Watch out for razor blades, broken tools and glass and the like when handling WWs. Think carbon, man. Just remember not to add anything even remotely close to having water on or in it unless you start from a cold pot. Once your scrap is cleaned up and poured off into ingots for later use, the cleaner fluxes likes paraffin, PatMarlins flux, clean nondetergent motor oil, sawdust, Marvelus - if you are so inclined - work good in the casting pot. When I render range scrap I leave all the trash like wood chunks, target pieces, shotgun wads, etc, in it. Works just fine in the 'smelting' pot. Anything that gets hot enough can flare up.

[BulletFactory]

If its carbon that we need, then why isnt everyone using charcoal? Wouldnt that be the easiest place to get it?

[DanM]

Most here don't care for the Marvelux because it is very hydrophylic. The stuff soaks in the moisture from the air and forms a solid block when stored. It can get so wet that it can cause splatter problems in your pot. Sawdust from a resinous type wood works well. I am not sure about the chemistry involved, but a stirring with a stick of wood will usually do the trick. Candle stubs are another choice.

[Hurricane]

I use sawdust to flux. Make sure it is dry. I put a small handfull in the pot and and stir either with my ladle or a wooden stick. The sawdust will turn black and then have a moderate flame. It is not an explosive flame. I have used a bit of candle from time to time but I prefer the sawdust, or stirring with a wooden stick (go to a store that sells paint and get some stirring sticks). The candle has a larger and faster flame, it can startle you if you are not ready for it. I don't want anything near me that might startle me in the presence of a pot of 700 degree lead. I use a ladle so I remove the burned sawdust ashes from the lead before casting boolits. If you use a bottom pour pot you can leave the sawdust ashes on top of the lead and let them continue fluxing while your pour boolits. Be sure to wear a face shield, long heavy gloves (welders gloves at a Home Depot or Lowes or a hardware store), long pants and long shirt sleves and shoes. Small splatters of lead are likely to get you if you do not dress for protection. Once you get that all done it is a lot of fun to make your own bullets.

[Smoke-um if you got-um]

I've used pieces of broken crayons from the kids and now my grandkids for over 30 yrs. Drop it in, light it off,stir and skim. Be ready to light it off within a couple of seconds or you will get a lot of smoke. I have a long nose lighter in hand when I drop it in the mix. Works well. Good luck.

Mike

[zxcvbob]

Lard or Crisco works really well for flux. It seems to work better than wax, and doesn't flare up as bad. Also doesn't smell as bad as used motor oil (that works too.)

[dragonrider]

Sawdust in addition to being an excellent fluxing material, will also keep you pot clean.

[geargnasher]

Here's my take on it, copied from a post I made on another thread:

Most of the time when we say "flux" in the context of boolit alloys we mean "reduce oxides", as in add something that will cause a reduction/oxidation reaction at the melt's surface and chemically render the dull, scummy layer of dross on top of the molten lead back into elemental lead, tin, and antimony (whatever is present in your alloy).

Different ways to do this, but the priciple is to introduce carbon AND carbon monoxide to the oxidized metals so they can exhange oxygen and make carbon dioxide gas. The short version is that most of the time you want to put something on your melt that will smolder or burn yellow if you light the smoke it gives off, yellow flame has lots of carbon monoxide in it due to the inefficient burn down in a lead pot where oxygen is scarce. CO and C will suck the O2 away from the metal oxides, leaving pure metal and giving off CO2.

How to do this? Introduce hydrocarbons. Like a wooden stick, sawdust, PatMarlin's Califoria Flake Flux, shredded newsprint, oily pine knots, boolit lube of any kind, or my new favorite: Juniper tree sap!

Marvellux and Borate compounds work differently, they are simply a means of sealing the melt's surface from oxygen to keep it from oxidizing in the first place. You can accomplish the same thing with Kitty Litter or a layer of sawdust in most cases, unless casting at very high temperatures (over 750 degrees in my book) for certain things like pure or near pure lead muzzleloader projectiles where high heat is needed for good fillout.

Most of the time, though, just toss in a couple of lubed boolits, stir the whole melt really well with a stick, light the smoke, and corral and skim the ash with a spoon, if you don't overheat your melt you only need to do that once each time you add lead, the slight oxide layer that does form will be fairly stable for an hour or more, the key is don't overheat your melt, because heat accelerates oxide formation drastically.

Gear

[cbrick]

This will answer all your questions on flux.

Fluxing the melt (http://www.lasc.us/Fryxell_Book_Chapter_4_Fluxing.htm)

Rick

[fredj338]

Yeah, use rubber tire stems only if you hate your neighbors or live in the sticks. I have used a bunch of diff stuff & have settled on sawdust of any kind, not form plywood or treated woods though. It seems to work faster & more completely than wax based stuff. For casting w/ clean alloy, I just stir occasionally w/ a wood paint stick.

[MikeACP]

Much more detailed explanation than I got from searches. Thank all of you. I think link is bad cbrick.

[bumpo628]

Much more detailed explanation than I got from searches. Thank all of you. I think link is bad cbrick.

Here it is:
http://www.lasc.us/Fryxell_Book_Chapter_4_Fluxing.htm

[songdog53]

I have used sawdust and now i am using up some old lube i used to pan lube my boolits with works good and will burn long time and when is out i find it far superior to store bought lubes that cause everything to rust. Yes, i have some but don't use it any more.

[Defcon-One]

Old Candle stubs work for me. Just a small chunk (3/4 Inch or so) in the pot and stir. Light it up to kill the smoke, if you want. Works great and the wife always has some half burned candles around the house for me to "borrow".

[cbrick]

Link fixed, sorry about that.

For those willing to do a little reading you'll learn why waxes & oils aren't the best way to flux.

Rick

[gray wolf]

So, in summary, the job description of bullet metal flux is to remove, reduce and protect.

OK, so how do all the different materials that have been used to flux lead alloys work, and which ones work best for the bullet caster? Pretty much everything that smokes, fizzles, pops and burns has been used to flux bullet metal. What do each of these candidate fluxes offer and how do they work? Or do they?

One of the more common classes of “flux” (the quotation marks are being used here because these materials don’t form a fusible mass and hence don’t fully satisfy the formal definition of “flux”) described in the older cast bullet literature are the various oils (e.g. used motor oil, vegetable oil, etc.) and waxes (e.g. paraffin, beeswax, etc.). Whoever came up with using used motor oil to flux his lead pot was either a lifelong bachelor, or must have liked sleeping on the couch, ’cause that CAN’T be a good way to make points with one’s Better Half! Aside from smoking like a chimney and stinking to high heaven, used motor oil also has the disadvantage of being a source for contaminating metals (ferrous alloys, aluminum alloys, bearing metal alloys, even magnesium depending on what motor it came out of). Oiled sawdust was another popular choice in years gone by. It would have suffered from many of the same smoky, stinky drawbacks that used motor would have. Let’s all do ourselves (and our families) a favor and just scratch those two off the list….

Various waxes have also been used to clean bullet metal. Most commonly these have been paraffin, beeswax, various forms of tallow, or even lard. These have the advantage of being cheap, universally available, and working reasonably well (depending on the alloy). These materials are very good at satisfying two out of the three selection criteria for bullet metal flux in that they are excellent reductants and can reduce any oxidized tin present, and they can be used in sufficient quantity to form an excellent barrier layer, thereby preventing any subsequent oxidation of the alloy. Unfortunately, they offer no means for removing any Ca, Zn or Al impurities. If one is working with a relatively clean source of bullet metal (e.g. linotype or foundry metal), then the waxes can serve admirably in this capacity. However, if one is using a dirtier source of lead (e.g. range scrap, battery plates, or WW alloy), then there are probably better choices. Then there is also the minor issue of distraction; using lard as a cover material makes the lead pot smell like a deep fryer. To this displaced Southern Boy, the odor of fried chicken coming from the lead pot makes it difficult for me to concentrate on the matter at hand. One should not be licking one‘s fingers while casting bullets….

One of the materials that is currently sold as bullet metal flux includes pine rosin. While pine rosin smells nice (it makes the lead pot smell like a pine campfire) and does a reasonably good job, it operates pretty much the same way that the oils and waxes discussed above do, and is therefore limited in its ability to remove detrimental impurities.

Some of the commercial fluxes on the market today contain boric acid, borax, or other borate containing materials (e.g. Marvelux). These materials are fluxes in the true definition of the term since they melt to form a borate glass which entrains any oxidized materials and extracts these contaminants into the molten glass phase. These fluxes have the significant advantage of being smoke-free and odorless. They are also extremely effective at removing contaminants. This is because the borate anion binds all metal cations and extracts them into the molten borate glass. Unfortunately, this includes any oxidized tin, and so the alloy is depleted of this valuable component. The borate fluxes do nothing to reduce the oxidized tin, nor do they protect the melt from further oxidation. You’ll note that this behavior is exactly opposite to that of the waxes, described above.

Is there anything that combines these two modes of operation so that we can get all three of the desired attributes? Fortunately, there is. What’s more, you probably already have a pile of it in your shop. It’s good ol’ fashioned sawdust (hold the motor oil, thank you). The benefits of sawdust are that it‘s a sacrificial reductant that can reduce any oxidized tin back to the metallic state, and it‘s cheap enough that the caster can use enough to form an effective barrier layer to protect the alloy from subsequent oxidation. What’s more, as the sawdust chars on top of the melt, it forms activated carbon, which is a high surface area, porous sorbent material that has a large number of binding sites capable of binding Lewis acid cations like Ca, Zn and Al. So it not only keeps the tin reduced and in solution, but it effectively scavenges those impurities that raise the surface tension and viscosity of the alloy (Al, Zn and Ca), keeping the alloy in top shape for making good bullets. Vigorously stirring in a heaping tablespoon of sawdust into a pot full of bullet metal does a fine job of conditioning and protecting that alloy. Sawdust doesn’t really qualify under the formal definition of “flux” as it doesn’t produce a fusible slag, but it does very cheaply and very effectively accomplish the three primary goals that we set out for cleaning up bullet metal. Reduce, remove and protect, sawdust does it all!



You should have the answer by now with all this info.

[MikeACP]

With the exception of one thing. How much? If I were using saw dust for example with about 20lbs of WW. How much do I introduce into the pot? And this thread has answered a lot questions and is an education. Thanks to everyone.

[gray wolf]

For a pot with about a 5 inch surface area like a lee 20#pot I use about 1 inch of
very thin pine shavings. I use an inch because they are shavings and not saw dust.
Use less saw dust as it will compact more than shavings.
Sprinkle on the top of the melt and don't mess with it until it is good and brown
It could and probably will have moisture in it
let the moisture burn off ( remember no water in melted lead )
Stir it through the melt well with a wooden stick or an old spoon. Leave it on top of the melt as an O2 barrier ( keeps the air off the melt and will keep the metal from oxidizing )
For a bottom pour pot: leave it alone till you add metal, before adding remove all the old saw dust ash and skim any dirt from the top of the pot. Add your new metal and repeat the saw dust application as above. If you add metal sooner you should be able to just give the pot another stir or two with your (DRY) wooden stick.
Saw dust for smelting may require you to push the ash away and dip through it.
Or use a good bottom pour ladle that takes metal from the bottom of the bowl. This allows the burned saw dust ash to remain on top and will give you clean ingots.
There are many ways to do this with good results. If you don't have enough saw dust on your melt you will know it. It will pull away from itself and expose some of the metal to the air.

[MikeACP]

Thank you.

[cbrick]

Should give credit for the qoute in post #17 to:

Glen E. Fryxell

It is a cut & paste from his book.

Rick

[zxcvbob]

Do you have a brass tumbler? The worn-out tumbling media -- walnut shells or ground corn cobs -- works about like sawdust, although it doesn't burn up as fast. I use that when I'm casting boolits. (I still like cooking grease better when I'm casting ingots)

[gray wolf]

Should give credit for the qoute in post #17 to:

Glen E. Fryxell

It is a cut & paste from his book.

Rick

My post # 17 was cut and pasted from Glen E. Fryxell new book, and I didn't state it as such.
I thank you so much for bringing it to my attention, and the attention of everyone here.
Boy you are sharp to pick up on things like that. I am sure everyone else thought It came from my own brain.
It's the sharp observant folks that find little things like this that add so much to the hobby.
Perhaps we need an anti plagiarism task force.

[MikeACP]

Yeah, I have walnut media. My first thing will be smelting ingots. I'll build up a supply of those while I collect casting equipment.

[cbrick]

gray wolf, I didn't think you were trying to take credit, just wanted to make sure Glen did get the credit.

Rick

[gray wolf]

CBRICK

No problem, just a slip on my part, naturally he gets the credit--he did the work.

[Springfield]

As to how much, just keep adding sawdust until the burned sawdust is ash with no lead looking stuff in it anymore. If you ladle it off and it feels heavy then it isn't done either. Sometimes I get in a hurry and flux my pot and scoop off the ash but it sticks together in my dross container. Later I (carefully)pick through it and take out all the chunks and put it back in the pot, and flux some more. It always comes out smaller and lighter as long as I have fluxed enough. For me the magic temperature, which no one has mentioned so far, is about 675deg. Just enough to make it flash on it's own, but no more. I usually run a bit under that and light it with a B B Q starter. If it is to cold it won't flux properly. It probably varies with alloy but that is the temp that works for mine in my pot.

[kyswede]

I just had an idea. I love the smell of a good cigar, but don't smoke them anymore. I use sawdust/wood chips to flux. What if I put a small piece of cigar in with the sawdust? Basement would smell nice I think. Has anyone done this?
kyswede