Fluxing and keeping lead from surface oxydation.

[GregLaROCHE]

I normally flux my range scrap with sawdust two or more times before I pour it into ingots. When I cast boolits I melt my ingots and may add some tin. I flux this with sawdust and add about a teaspoon of beeswax. Stirring and then leaving the charred sawdust etc stay on the top to make a seal from the air.

I’ve come across others who use cat litter to cover the alloy when casting. Is there an advantage to using this method ? Do many others do it? Is there a better way than just leaving the old flux on top?

Thanks

[country gent]

Its the carbon from the wood chips wax pet litter that keep the oxygen away from the lead. When welding food transfer popes in one plant they were purged on the inside with argon co2 mix when welding this pushed the oxygen from the tube and stopped the oxidation and flash thru, leaving a weld that looked like the bead on the outside where it was actually welded. Your "purging" the oxygen from your melt with the carbon layer on it.

[GregLaROCHE]

Isn’t cat litter made from clay not carbon? That’s why I thought there could be some other advantage to it. Once when my sawdust got wet, I used Quaker’s rolled oats and it worked fine.

[Rcmaveric]

Anything that can create a barrier between the molten alloy and oxygen will work. I use the saw dust a couple times during smelting. In the casting pot i use wax as the wetting agent and then use borax to clean the alloy and then more borax to seal out the oxygen.

You can use kitty litter all that is is just clay. Saw dust if left in a thick layer. I like borax because it buffs up and expands so it only takes a little bit. You can even use a thick layer of molten wax. Molten wax does a have a **poof** potential though.

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[Rcmaveric]

Isn’t cat litter made from clay not carbon? That’s why I thought there could be some other advantage to it. Once when my sawdust got wet, I used Quaker’s rolled oats and it worked fine.Cat litter is made from clay. There is no extra benefit from it. Its just a cheap cover material. Same thing would happen if your poured sand or dirt into the pot. Kitty litter is just easier to clean out.

Organic things like woods and oats ext will turn to carbon which is good for the alloy and purfies it. The sap in pine saw dust will help wet and reduce the oxides back into the alloy. Pine saw dust is the closest you can fet to a true flux for lead. Everything rlse we use needs to be used in combination to actual reduce, wet, and clean the alloy.

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[lightman]

I use wood chips or sawdust when smelting followed by beeswax. I only use beeswax in my casting pot and don't worry too much about oxidation.

[Shuz]

I flux with Marvelux, and then cover with new unscented kitty litter. My understanding is that kitty litter is a type of clay known as diatomaceous earth. A property that it has, that I've noticed, is that after a while it breaks down into a real fine dust which covers the melt perfectly. Helps keep the heat uniform and the air out. It is also an excellent oil adsorbent for those times when oil is spilt on a concrete floor!

[dondiego]

Diatomaceous earth is the glass skeletons left behind by diatoms which are a single celled, aquatic plant related to algae. It is almost always white. Often used in swimming pool filters. Clay is different and comes in many forms and colors. It is a very fine particulate.

[waksupi]

I really advise using a stick to stir the pot. It gets down into the melt. Due to the specific gravity of lead, there is no way you can stir anything put on top of the alloy down into it.

[mdi]

I've not been too concerned with top "scum", and I stir often with a wooden stick during casting. In my mind stirring keep the alloy from separating(?). The "clay" cat litter used to be just diatomaceous earth (a zillion little tiny fossils), same as "oil dry". When put on top of the melt it just seals it from the air. I hadn't read of any "oxygen barrier via carbon", but there's a lot of stuff I don't know!

No tellin' what cat litter is today. When we had our cat we found a litter called "Good Mews", which was a compressed paper like substance. Hard little pellets that resembled rabbit food. I used it for tumbling brass for a while...

[Grmps]

I flux with both pine sawdust and wax.
I use a potato masher to get the flux to the bottom of the pot
then I use a wire whisk to finish getting a through flux.
I leave a 1/8 - 1/4 thick layer of chard/ fluxed sawdust granules on top of the pot to work as both an air barrier and to prevent splashing when returning sprues to the pot

[Mr_Sheesh]

Kitty litter (non clumping) is "Fuller's Earth", can have various things in it including some diatomaceous earth but mainly clays like Kaolinite IIRC?

I've never used it though. Mostly lots of wax :)

[GregLaROCHE]

So pine sawdust is better than others. I didn’t know that. From now on I’ll start separating it. I’ve got all kinds of sawdust.

[psweigle]

I use sawdust and crayons. Just have to sneak them out when the grandkids arent looking.

[WheelgunConvert]

I like using crushed walnut shell lizard litter. It’s also useful in a turbo cleaner as media.

Another handy use for the diatomaceous earth is to dust cats and dogs to keep them flea free...maybe ticks too. I’ve also read about it being used as a dust treatment for roaches.

[Gtek]

Temperature control is my first concern, over heating just seems to makes things worse. Sap sticky yellow pine sawdust and stirred with cedar shim sticks on big meltdown pot, peas of wax on little pots when it's boolit time.

[dondiego]

Georgia fatwood sticks used to start fires are good for stirring in and smell great too! Diatomaceous earth is about 1000 times more expensive than clay which leads me to question it's use for cat litter.

[mdi]

I flux with both pine sawdust and wax.
I use a potato masher to get the flux to the bottom of the pot
then I use a wire whisk to finish getting a through flux.
I leave a 1/8 - 1/4 thick layer of chard/ fluxed sawdust granules on top of the pot to work as both an air barrier and to prevent splashing when returning sprues to the pot

Cool idea, I never thought of that. I use a slotted spoon, bent 90 degrees to help mix my sawdust in the melt...

[Grmps]

Burn pine sawdust
https://i.imgur.com/7lOl5XV.jpg

https://i.imgur.com/va1G7Jg.jpg

https://i.imgur.com/ym58WOH.jpg

https://i.imgur.com/6t89otB.jpg

https://i.imgur.com/Jgcg8z8.jpg
if I don't get fine granules like this I flux (again) with wax

[country gent]

I ladle cast from a bigger gas fired pot. I use a long handle barbeque spatula to flux and stir then a long handled slotted spoon to remove most of the crud the last gets a regular serving spoon. I flux with wood chips and wax but don't leave a layer on the pot since I ladle cast'
I keep the ladle in the pot to maintain temp and when I start a pour while filling the ladle I push it down and make a swirl around the pots dia this maintains the mix and helps maintain temp on in the ladle.
I have read where some of the old shutzen shooters and cast accuracy shooter had a stirring set up that ran to keep the pot mixed and blended from start to finish. A small flat blade turning at 5-8 rpm 2-3" dia circle would keep a pot mixed pretty even.

[Bird]

I use only beeswax. A lump of it flows across the surface and forms a barrier. Give it a stir every 20 mins, and add a little more.

[BNE]

Fluxing is one of those topics voted MOST LIKELY TO START AN ARGUMENT! This one has been surprisingly nice!

I am in the wax / sawdust camp. I even made sawdust chunks full of wax that I break off into the pot.

Tin Depletion?
I have done XrF tests that show that the amount of Tin you lose to oxidation is not measurable. The test involved leaving a pot on around 800F for a couple of hours. I would scrape the top layer off and XrF at different time intervals. Tin was not depleted in this time period.
Leaving a layer of kitty litter or something else on top of the melt is not helping you keep Tin in the mix.

BNE

[sureYnot]

Thank you, BNE. I had been under the impression that tin oxidized faster than lead. Any insight as to the effect on antimony? Or arsenic?

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[BNE]

Thank you, BNE. I had been under the impression that tin oxidized faster than lead. Any insight as to the effect on antimony? Or arsenic?

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Tin does oxidize more quickly than lead, but once that top layer oxidizes, it basically protects the lower layers.

In the test I ran I was not specifically looking for Arsenic, so I can’t answer that one. The percentages of Lead, Tin, and Antimony did not change.

[sureYnot]

Tin does oxidize more quickly than lead, but once that top layer oxidizes, it basically protects the lower layers.

In the test I ran I was not specifically looking for Arsenic, so I can’t answer that one. The percentages of Lead, Tin, and Antimony did not change.Good stuff. Again, I thank you.

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[EDG]

In the investment casting industry they often use an argon drip or line to provide a blanket of inert gas on top of the molten metal in the crucible.
For our little pots a stainless steel disk could be floated on top of the lead. This disk will mechanically reduce the surface area of the melt exposed to oxygen.

I once worked at a small shop that had a casting setup to cast silver. The crucible had an airtight cover with an argon purge gas line. There was also a short rubber hose that was a pressure relief exhaust in the cover. In use argon flowed on top of the molten silver. To cast you merely put your thumb over the end of the pressure relief line. The argon built up enough pressure on top of the molten metal and forced it out through a submerged goose neck. The goose neck delivered the silver into a mold mounted on the machine.

[jonp]

I use a potato masher to get the flux to the bottom of the pot

:idea: I will now. psst..don't tell my long suffering wife where another of her kitchen gadgets went. I'm still trying to explain the cast iron dutch oven and the blender ( So...you were chopping up aluminum foil for what, exactly???).

[hermans]

Fluxing is one of those topics voted MOST LIKELY TO START AN ARGUMENT! This one has been surprisingly nice!

I am in the wax / sawdust camp. I even made sawdust chunks full of wax that I break off into the pot.

Tin Depletion?
I have done XrF tests that show that the amount of Tin you lose to oxidation is not measurable. The test involved leaving a pot on around 800F for a couple of hours. I would scrape the top layer off and XrF at different time intervals. Tin was not depleted in this time period.
Leaving a layer of kitty litter or something else on top of the melt is not helping you keep Tin in the mix.

BNE

I tend to agree with BNE...not because I could measure the amount of tin lost to oxidation, but just because I can constantly produce perfect boolits from COWW without worrying too much about leaving a protective layer on top of the alloy in the pot.
What I do is stir well with a wooden stick, then add beeswax generously, and try to cast at the lowest possible alloy temperature, controlled with a PID, usually not higher that 695 degrees.
Happy casting[smilie=s: