powder laundry soap verses Borax

[loader]

Hey Guys,

I use Borax for flux. while smelting ingots. My wifes buys borax to control ants, so I use to flux the pot. It's only four bucks for four pounds. I know I can use saw dust and it would be free, but I really don't like relying on other people to supply me anything. Yeah I know, go to a lumber yard or home depot and get it. I could. How well does saw dust work?

[Blammer]

works fine for me, I just ad a little and stir, of course I'll use about anything for flux

[runfiverun]

the sawdust is for the carbon it needs to be charred into ash then you need an oxygen free zone to reduce the oxides back into the melt.
hence the fire part.
borax does fine but remember it will hold tin in suspension as well as other metals in the mix.
and it is hard to get them to release back into the alloy.

[btroj]

Is your wife using borax or boric acid? Different things.

I have seen boric acid used as a flux, similar to Marvelux. What a mess. Boric acid is also used to kill ants.

I will stick to sawdust of a paint stir stick for fluxing. They just work.

[loader]

the sawdust is for the carbon it needs to be charred into ash then you need an oxygen free zone to reduce the oxides back into the melt.
hence the fire part.
borax does fine but remember it will hold tin in suspension as well as other metals in the mix.
and it is hard to get them to release back into the alloy.

borax does fine but remember it will hold tin in suspension as well as other metals in the mix.

I know that you're not making this up... so,.. how do you know this? What's the solution to clean it all?

[theperfessor]

I've never used anything besides sawdust or vegetable waste for flux so I can't say if there are other, better methods. But I've come to believe that this is a cheap and easy way to clean your melt. Bret4207 (and many others here) tout using sawdust and stirring with a dry wooden stick. I've processed a lot of scrap lead including roof sheathing covered with tar, drain pipes filled with, uh, "residues", wheel weights, and "mystery metal". Sawdust, stirring with a hardwood stick, and good skimming has worked every time.

[dragonrider]

Sawdust works like majic, but only after it chars completely, don'[t go mixing it before that happens and once ti does liftup ladlesful of lead and char anf from a hieght of 6 to 10 inches pour it back into the pot,This will keep your lead moving virgorously getting a lot of contact with charred sawdust. If you pot is dirtry from other psuedo fluxes sawdust will clean it up. I have been using it for some years and will not use anything else.

[captain-03]

Sawdust in my pots - always!!

[cbrick]

I know that you're not making this up... so,.. how do you know this? What's the solution to clean it all?

Here it is explained very well in plain simple english. Chapter 4 is on flux.

http://www.lasc.us/Fryxell_Book_textonly2.pdf

Rick

[John Boy]

borax does fine but remember it will hold tin in suspension as well as other metals in the mix.
and it is hard to get them to release back into the alloy.

I only get ash in my dross. I've been using borax for about 3 years and cast several hundreds of pounds a year. Plus, in a 20 lb pot, after fluxing twice with borax, I don't see any additional dross to the bottom of the pot

[loader]

So cleanliness of the lead creates better flowing which causes better mold fillout (raise surface tension and viscosity).

The carbon in the wood creates a porous sorbent which collects impurities once burned into carbon...

and allows tin to go back into a (metallic state, and not oxidize). I'm not grasping this concept).

[Bad Water Bill]

I have used borax for years for a cleaner laundry AND in my SHOES to get rid of that nasty smell.

[noylj]

I'm too old. I use wax, bullet lube, and industrial fluxes and ignite them all when they start to really smoke. A good DRY wooden stir stick is good, too, but I still use the old restaurant drain-spoon I started with about 35 years ago.

[williamwaco]

================================================== ==

I'm too old. I use wax, bullet lube, and industrial fluxes and ignite them all when they start to really smoke. A good DRY wooden stir stick is good, too, but I still use the old restaurant drain-spoon I started with about 35 years ago.

================================================== ==

Me too. I have used sawdust too. It does a good job but the smoke really chokes me and messes up my eyes and I have to scrounge it from friends with wood working shops.

I use rejected bullets which have been lubed with alox / beeswax when they are avaialable. Most of the time, I use scrap candles. If the melt is hot, the fumes will ignite and there will be no smoke.

[geargnasher]

So cleanliness of the lead creates better flowing which causes better mold fillout (raise surface tension and viscosity).

The carbon in the wood creates a porous sorbent which collects impurities once burned into carbon...

and allows tin to go back into a (metallic state, and not oxidize). I'm not grasping this concept).

Do you have any background in inorganic chemistry, even a high-school class? If you have, this might help you understand. When you melt and heat an alloy, the surface oxides of the metals float to the surface. Continued contact of the surface with the oxygen in air promotes further oxidation of the metals. Tin oxidizes out of the melt much faster than lead, and tin is needed for improved castings, plus is expensive to add back at $18/lb, so you want to preserve it, rather than skim it all off and throw it away.

We know that sawdust, or ANY hydrocarbon smoldering on the surface of molten lead alloy, is actively inducing a reduction/oxidation reaction (or REDOX reaction), because of the chemistry involved. PbO2 + SnO2 + HC --> Pb(s) + Sn(s) + CO2(g) + H2O(g). That's not balanced and not all that goes on, but it's a crude representation of the reduction of the metal oxides and the oxidation of the hydrocarbons that is taking place. The last stage of the Galena smelting process that yeilds lead from ore is to introduce the molten metal to carbon monoxide (CO), which readily reduces the PbO2 to Pb and yields Pb elemental and Co2 gas.

Sawdust does more than just reduce oxides, it actually fluxes the melt by drawing out and removing the things that are considered impurities to boolit casters. The borate fluxes capture the valuble tin and remove it, and serve only to seal the melt's surface from further oxidation. The only use I can think of for borate "flux" is with pure lead being cast at very high temperature, in excess of 800 degrees.

Sawdust works better than borate glass in any situation I can think of. So to answer your other question, SAWDUST is your solution to clean it all. Just stay away from sawdust that has poisonous stuff in it like formaldehyde in plywood sawdust, or pressure-treated lumber dust.

Gear

[loader]

Well I went to home depot and got sawdust from the vertical saw for cutting plywood. Guess I need to toss it, according to you.

Do you have any background in inorganic chemistry, even a high-school class?

Nope.
Thanks for the write up, gear, but I didn't have chemistry in HS. Lost cause. I can gather that Carbon gathers inpurity, and blends tin in the alloy. I used Borax to flux, and did not remove anything, that I could see anyway, form the pot.

So by using the borax with WW's what happened to the tin? It's in suspension? And will not do it's job... help lead to fill out the mold?

What can I do to fix the ingots I made with fluxing with the Borax? Will the sawdust bring tin out of suspension?

[cbrick]

Well I went to home depot and got sawdust from the vertical saw for cutting plywood. Guess I need to toss it

You can use it, it will work fine but you do need to make sure that you have really good ventilation. I have used a huge amount of sawdust from plywood with no problems but I have a strong vent fan in the ceiling about 36 inches above my pot. I can stir the melt with the sawdust smoking like crazy and standing next to the pot I can't smell it. If your ventilation isn't good enough to remove all of the smoke just flux outside.

I can gather that Carbon gathers inpurity, and blends tin in the alloy. I used Borax to flux, and did not remove anything, that I could see anyway, from the pot.

Yes, the Borax will remove impurities such as aluminum, copper etc, it will also remove the tin, not something you could see looking at the melt. Sawdust works by a different mechanism than Borax, the sawdust will "reduce" tin. Reduce in metallurgy simply means to put the oxidized tin back into the melt (alloy).

So by using the borax with WW's what happened to the tin? It's in suspension? And will not do it's job... help lead to fill out the mold?

Correct, if the tin isn't there it can't help much. On the bright side WW has only about 0.5% tin anyway unless you have added additional tin to the melt.

What can I do to fix the ingots I made with fluxing with the Borax?

Simply flux with sawdust and if you wish add up to 2% tin just before fluxing.

Don't feel bad, I used Marvacrap for several years. One of the very happiest days of my life was the day I discovered sawdust and threw the Marvacrap in the trash can. I wouldn't allow that horrid stuff on the property again much less in the shop or anywhere near my casting pot. It will coat the inside of your pot with black rock hard borate glass, to remove it you'll spend the afternoon with a stiff wire wheel in a drill motor creating copius amounts of toxic dust. Do this outside and wear a quality dust mask.

Rick

[geargnasher]

Well I went to home depot and got sawdust from the vertical saw for cutting plywood. Guess I need to toss it, according to you. I can't assume that you have a dedicated, safe casting setup with sufficient ventilation to keep you from huffing bad fumes, hence the caution. Like Rick said, plywood sawdust is fine as long as you don't breathe it. Pressure-treated lumber, while not at bad as it used to be before the EPA banned the arsenic content, it does contain significant amounts of copper compounds and other stuff you shouldn't ever breathe.

Thanks for the write up, gear, but I didn't have chemistry in HS. Lost cause. I can gather that Carbon gathers inpurity, and blends tin in the alloy. I used Borax to flux, and did not remove anything, that I could see anyway, form the pot. Uhh, not exactly. You can't see tin in suspension without an electron microscope. The carbon is reacted chemically and changed into carbon dioxide gas. The other part of the chemical reaction (redox) is that the lead, tin, and antimony oxidesgive up the oxide part and they are transformed back into pure metals. The ash that remains together with some unburned carbon actually does act like a physical sponge, soaking up impurities. Sort of. It's more complex than that, but that's the gist.

So by using the borax with WW's what happened to the tin? It's in suspension? And will not do it's job... help lead to fill out the mold? The tin and other metals are in suspension with the borax, not the liquid metal. The borax sucks them up and holds them forever. You throw away the tin with the dross, no way around it. A small amount of tin helps fillout by creating an oxide barrier to the molten lead as it flows, like a shield. The tin flash-oxidizes on the surface of the lead, and since tin oxide is more flexible than lead oxide, it actually makes the lead flow better by keeping the lead surface from oxidizing as it flows into the mould. Basically, tin makes lead flow like water instead of pancake syrup.

What can I do to fix the ingots I made with fluxing with the Borax? Will the sawdust bring tin out of suspension? No, once the tin gets sucked up by the borax, it's gone. Probably not anywhere near all of your tin was trapped by the borax, so don't worry too much about it, but some was lost to be sure. Just add a half-percent back and you should be fine.

Hope this clears it up some,

Gear

[MtGun44]

The tin is "rusted", or oxidized by combining with oxygen in the air. The is like iron
rusting or a very slow version of burning. To reverse the process, you would be turning the
rust back into iron, and in the case of the tin oxide, you are pulling the oxygen back
off of it to give yourself metallic tin again. Reversing the chemical reaction that is
oxidation of the metallic tin into tin oxide. Tin oxide isn't a metal, won't melt into
the alloy. By removing the oxygen, you release the pure tin and it can then melt
back into the alloy.

Maybe that is a bit clearer.

Bill

[geargnasher]

Good explanation, Bill.

Gear