Flux Options

[armednfree]

Looking for some info on fluxing. My supply of Marvelux is nearing its end. I remember hearing some time back about using 20 mule team borax or Boric acid, both of which I have large quantities.

Any input?

[Longwood]

Lots of conversations here about Marvelux.
I think I read one good remark about it a year or so ago.
It is said tried and many times proven that plain old sawdust, pine shaving pet bedding, walnut hulls, wet (so they break up) then dried wood pellets, pine needles, etc, works many times better.
Coffee grounds stink terribly so forget that.
After one try, I agree and I used wax etc for years and years.

[Longone]

I am a new convert, used to use Marvel flux and now I am working with corn cob media that I bought and is too fine for my taste. It smells better, keeps the pot MUCH cleaner and overall IMHO easier and certainly cheaper.

Try saw dust or CC media you won't look back.

Longone

[Defcon-One]

White pine sawdust.

AWESOME Flux and free!

[armednfree]

So you guys are just hindering oxidation, not actually fluxing the lead I take it.

[geargnasher]

Nope. Those of us who know to use sawdust are actually fluxing AND reducing. Those using grease/wax/oil are only freeing the oxides of oxygen (reduction), and those of you using marvellux or similar borate flux are only fluxing, not reducing.

Marvacrap pulls the things boolit casters consider impurites out of the melt such as calcium, aluminum, iron, iron oxide, and a few others. The problem is IT ALSO REMOVES TIN IN OXIDE FORM. Unless you dislike tin in your alloy don't use it. Tin oxidizes at a greater rate than the other elements in boolit alloy, therefore the oxide scum on top tends to have a very high tin percentage, and if you keep skimming it off you'll depleted the tin proportion in the alloy in short order. Marvacrap doesn't do any REDUCING, and though it won't absorb elemental tin, it absorbs tin oxide like mad. So if you use it, use a grease/wax/oil to reduce the oxides back in, then use the borate to flux and suck up impurities, and also for a molten glass barrier to seal the top of the pot from further oxidation.

Sawdust reduces oxides to elements, absorbs the impurities (if you stir the melt well and expose it to the charring sawdust) to the carbohydrates it contains, and if you leave the ash on top of the melt it makes an effective and non-hardening oxygen barrier unto itself. No messy glaze on the inside of your pot, nothing to absorb moisture and create tinsel faery visits on your skimming tools, and it's universally free from any cabinet shop, or make it yourself with a saw and knotty yellow pine. Pine rosin makes a most excellent reducant in and of itself, in combo with sappy sawdust, especially knots, it makes some of the best lead alloy flux you can get. If you use fine shavings or fine sawdust, you can light it with a BBQ grille butane lighter and the extra carbon monoxide the oxygen-starved flame makes improves the reduction process even more.

Basically, the reduction/oxidation reaction that is established when grease/wax/oil/wood contain works something like this: The aromatic hydrocarbons sacrifice themselves in the reaction. Metal oxides give up electrons and become elemental metals, the now free oxygen combines with the carbon to become CO2 gas, and the hydrogen combines in part with oxygen to become water (steam). There's some ash left over from the impurities which is skimmed off. If you use sawdust, it does all of that plus effectively "fluxes" the impure metals out as well. What you've made is water and CO2 and pure metals in the end, but dispose of the ash from sawdust fluxing in airtight containers because if the alloy contains calcium, the ash will absorb it in a form that creates phosgene gas as it absorbs moisture from the atmosphere. Don't put the skimmings in a steel juice can and leave it open in your garage, in other words.

Gear

[armednfree]

You say knotty pine. I have just plain old saw dust I can sweep off my table saw, mostly just plain pine, would that work?

Before I used Marvelux I used a chunk of bullet lube, Seemed to work fine.

Also, my lyman pot is a little off I guess. I have to leave it on for some time before the lead will flow from the spout. I use a dipper most often. The lead from the spout only seems to want to flow if I keep the pot on the 9 setting and let it cook for some time.

[geargnasher]

Actually I said "knotty yellow pine" :kidding:

No sweat, any kind of sawdust works just dandy except for plywood sawdust and treated lumber sawdust, nasty stuff all that is when heated. Cedar pet bedding, fresh coffee grounds, clean corncob media, walnut media, dry leaves, sticks, breakfast cereal, unsalted potato chips, lots of stuff like that works great. Sawdust seems to be the best, and generally stinks the least of all that sort of stuff though, and has the stuff you need an nothing you don't to do the job. Light the smoke when it starts to turn dark brown and put off white curls of smoke. You can add a bit of wax or boolit lube with the sawdust as well and light that too if you want to help keep the smoke down. Be sure and stir the alloy a lot while the sawdust is charring to expose as much of the melt as possible to it, that will help remove the dissolved impurities that can hinder the smooth flow of the alloy.

Gear

[evan price]

When I smelt bulk lots I use my drained motor oil. It's a carbon reductant. It also contains detergents and additives that were used to trap particles in the lube oil and transport them to the filter...this works the same for trapping the contaminants in the lead. I wind up with a 75# pot, with a cup of used oil added, stirred and flamed off, and there's a nice crust on top I skim off leaving mirror bright alloy underneath. DO this OUTSIDE.

When I work with my actual casting pot I stir it with the chopsticks I get from chinese take-out food. Some sort of wood or bamboo, works great to flux, leaves some ash on top. And they are free.