Is Flux important and what can I use?

Bret4207

At the casting bench in the sky. RIP Bret.
Bret, after reading the recommended articles, the flux seems to be removing the oxygen to change the oxide to a metal that can be mixed back into the molten lead. What about the lead in the bottom of the pot. What impurities are there that need to be removed? Or from the stirring, are the impurities being stirred to the surface?
Yes, you have to stir to mix the alloy and bring crap to the surface. Read Glens or Wacos articles on reducing. I dont[ know the chemistry of it, just what works for me.
 

Mitty38

Well-Known Member
I
Emmitt that filtering process would make a dandy video!!
Playing with some editing software. Down loaded Splice on phone.
If I set up for filming, it would probably need to be a bunch of short videos taken during the process. Spliced together.
So getting that figured out.
Would like to do a video of my whole process, once I get some more scrap.
 

Mitty38

Well-Known Member
Yes, you have to stir to mix the alloy and bring crap to the surface. Read Glens or Wacos articles on reducing. I dont[ know the chemistry of it, just what works for me.
Yep stir and mix the saw dust that is turning to charcoal, as it turns. Down into the pot. Then scrape the sides as it is working.
I kind of prefer a push down. Followed by a Slow but lengthy, thorough stir. Followed by a scraped then a bit of time for things to settle and float.

Never do any cleaning in Lee bullet pour pot. Have a separate set up for that.
However I may use wax, after fluxing in my Scrap cleaning pot. To help mix the good stuff, that may have sperated, back together. Before I pour my ingot.

If clean lead is made first into ingots, then put the pot, all you need to do is throw some kind of wax on top to make a kind of seal.
Or if it starts to separate, stir some wax in to make it bind itself back together.


Wax does not remove anything well.
It does two things, seals oxygen from getting in the mix. And removes oxygen while helping to recombine any alloy components that are separated.
Hope this helps someone understand.
Took me a good while to figure it out.
 
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popper

Well-Known Member
Wax does not remove anything well. It does 'stick' dirt together to make removal easier.
Dropped one off the dive weights BIL gave me. Darn, goes tink instead of thud. Gotta figure what it is. Nice cast with belt loops and a 3 cast into it. Maybe vinegar will react? No muratic left, maybe kid has some. Looks like Marine Diving hard lead weights. Wonder what roto dive hard lead weight have in them.
 
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fiver

Well-Known Member
seein as how dive weights are made out of anything lead like that melts and fills the mold...

back in the day my main competitor for ww's was a dive shop up in the northwest somewhere.
they sent a truck all the way down interstate 15 hitting up every shop they could see from the freeway.

anyway.
you need to make the distinction between reducing and fluxing.
sometimes the process is pretty darn close to the same, only one is done with carbon and one ain't.
 

JWFilips

Well-Known Member
you need to make the distinction between reducing and fluxing.
sometimes the process is pretty darn close to the same, only one is done with carbon and one ain't.
In smelting: I alway flux first with wood / Sawdust..... And run the lead over and over in the wood dust then it's charcoal! After that I remove what ever floats on top of the smelt & add a good size hunk of white pine congealed sap! Pretty smoky but try to stir as much as I can! Again scrape the surface of debris and finally ad a good hunk of raw bees wax! Mix it in until it ignites ....then let it seal the top of the pot...
move the crust out of the way and start pouring ingots!
Once the ingots go in my casting pot I only use Bee's wax as a reductant at about 620 degs & scrape what ever I can get off the bottom & sides of the pot, scoup that out then at approx 700 deg drop a hunk of bees wax back in to seal the melt and cast at 725 degrees !
I have only one 3 cavity 63 grain .260 mould that needs to be cast at 775 deg! That is the exception to my temperature rule!
 

Snakeoil

Well-Known Member
Used sawdust today for the first time. Actually, used wax to start out. I had dumped a bunch of lubed bullets in my pot and when I fired it up in the basement, it started to smoke. It just got worse so I shut it down and took everything out to the garage. The lube eventually was done smoking. I cleaned out my table saw and got a box of sawdust. I was amazed at how well it worked. No sign of tin separating out on top of the melt when I pushed the charcoal away. I fluxed every time I dumped the sprues back into the pot and left the charcoal on top.

It is a bit smokey. Would not have worked in the house. I also noticed that there were some metal solids that formed in the charcoal. Small nuggets of metal, that I assume the charcoal removed from the melt. They would not remelt. I scooped them out when I was done casting. Curious what they are. Aluminum, antimony, silver???

Guess I'll be casting in the garage from now on. Need a better stool.
 

Ian

Notorious member
The little shiny pellets that form among the charcoal granules are oxides of the parent alloy which have been reduced and are now pure casting alloy again. They don't want to mix back in due to surface tension of the top of the melt and the fresh oxide layer that forms instantly on any exposed surface of the melt. Corral and squish the charcoal/reduced metal clumps against the side of the pot to squeeze out the metal and get it to go back into solution. The little burnt tin-foil crumblies that won't reduce further in the presence of the charcoal are the aluminum, calcium, and maybe trace zinc and other crap that you want to get rid of. The charcoal adsorbs a lot of the bad stuff you don't see, and if you skim the charcoal while it is hot and smoking before it auto-poofs and turns to ashes you can get all that junk out of the alloy.

Emmett, I'm fascinated by the filters you described. I've always wanted to filter alloy from my "smelting" furnace as I pour ingots because I know dang good and well the metal is still saturated with dust and fines caught in suspension even after letting the melt rest for a half hour or more. I figured it would take a lot of pressure to force the metal through any kind of useful (fine enough) filter so not really possible for a home-gamer, but it seems you have a solution. Please post at least photos of the filter media you have or let me know where I can buy some (I'm sure it's spendy) because I'd love to try this.
 

Mitty38

Well-Known Member
The little shiny pellets that form among the charcoal granules are oxides of the parent alloy which have been reduced and are now pure casting alloy again. They don't want to mix back in due to surface tension of the top of the melt and the fresh oxide layer that forms instantly on any exposed surface of the melt. Corral and squish the charcoal/reduced metal clumps against the side of the pot to squeeze out the metal and get it to go back into solution. The little burnt tin-foil crumblies that won't reduce further in the presence of the charcoal are the aluminum, calcium, and maybe trace zinc and other crap that you want to get rid of. The charcoal adsorbs a lot of the bad stuff you don't see, and if you skim the charcoal while it is hot and smoking before it auto-poofs and turns to ashes you can get all that junk out of the alloy.

Emmett, I'm fascinated by the filters you described. I've always wanted to filter alloy from my "smelting" furnace as I pour ingots because I know dang good and well the metal is still saturated with dust and fines caught in suspension even after letting the melt rest for a half hour or more. I figured it would take a lot of pressure to force the metal through any kind of useful (fine enough) filter so not really possible for a home-gamer, but it seems you have a solution. Please post at least photos of the filter media you have or let me know where I can buy some (I'm sure it's spendy) because I'd love to try this.
I have all my ingot making done for now.
I was going to wait till I could post it, before mentioning it. But Kinda beat myself to the chase.
It may be a little bit tilI can dig that stuff back out of storage. But will at least post some picks as soon as I can, get to where I can dig out the filter material.http://smelko.com/?page_id=336
Here is a link to the fiberglass material we used when we could not get stainless, untill we transitioned to ceramic foam. The stainless foundy filter company closed down last year.
Basically the same stuff. Sorry it is 30 microns that I filter to, not 25.
The 440 hole per inch is 30 microns.
You basically pour thru a filter you make with 100 hole per inch, then a 280 or so, then the 440. In that order. Catches the crap large to small so the larger stuff does not plug the next smaller screen.
 
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Brad

Benevolent Overlord and site owner
Staff member
I would expect that for our purposes a 100 would be adequate. This would catch sand, ash, etc in the melt and also allow for some good flow. Hell,I would even go with the 49/inch. It will filter out anything larger than .012.

Interesting concept
 

popper

Well-Known Member
Bored so melted a batch of un-needed bullets in the pot, about half a pot. Beeswax, then scrap paper on top. light and smoke. Very little 'trash' including burned PC. Might muffinize it tomorrow if I'm bored enough and start on the dive weights. Gonna be cold in the garage.
 

Mitty38

Well-Known Member
I would expect that for our purposes a 100 would be adequate. This would catch sand, ash, etc in the melt and also allow for some good flow. Hell,I would even go with the 49/inch. It will filter out anything larger than .012.

Interesting concept
Ye,
I probably go with way finer then I need. But has been a work with what you got. On the fly kinda thing. Dedicated to quickly solving a particular problem.
Going to try and do a bit of research and refine the whole thing. Bigger holes would make the process easier.