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stainless1911
11-24-2010, 07:21 PM
I was wondering why we flux the lead? I have heard it cleans it somehow, but how does it do that, when everything sits on top of the lead? You can't exactly mix melted paraffin with lead. I have heard of people using bullet lube or sawdust as well, but I don't get it. I put some white pine hamster bedding on the lead, (I diddnt have sawdust), and it sat there and smoked a lot, but what does that blackened pile of wood chips actually do? Besides make a bit of a mess.:-?

mini14
11-24-2010, 07:41 PM
I though the same thing, if i pour from the bottom who cares whats on top?

biscot
11-24-2010, 07:48 PM
A great article on fluxing by Glen Fryxell:

http://www.lasc.us/FryxellFluxing.htm

357 Voodoo
11-24-2010, 07:51 PM
This article http://www.lasc.us/FryxellFluxing.htm should answer much better than I possibly could. Check out some of the other articles too.

lwknight
11-24-2010, 07:52 PM
Stainless , I believe that your thinking is correct.
1.
The fine particles of contaminates are suspended in the lead and will eventually float to the top. If you stir it the fines will never make it to the top.
2.
You will never get flux mixed into the lead.

3. You can actually let the lead sit melted and undisturbed for some time and skim the top and get it just as clean as a guy that uses 10,000 pounds of candles and sawdust.

So with all that in mind, the reason to flux the mixture is to allow the particles of junk to be released to the open air where they show up as dust.
If you don't flux and do stir the alloy , you just mix what has tried to float out , right back into suspension.
Secondly , fluxing reduces tin and antimony back into the melt so that you don't toss it out with the dross and comtaminants.

arcticbreeze
11-24-2010, 08:01 PM
I don't flux as much as i used to. What I do find in my unscientific experience is if I have the oxidized skin and buggers on the top of the melt fluxing will re-incorporate most of it back in to the alloy. I have heard that the tin in the alloy oxidizes faster than the other components and that is why I do still flux. If I don't flux the amount of skim is substantially more. I don't know for sure if I am correct or not but that is what I believe.

By the way I use pine sawdust thrown on top then a small piece of beeswax on top of that. Once the beeswax melts into the sawdust I light it off if it has not on its own then stir pretty well while it burns off. I have found this to be the most effective so I assume the carbon and combustion at the surface coming in contact with the alloy is where the magic occurs.

mini14
11-24-2010, 08:04 PM
well i guess it does matter

oso
11-24-2010, 08:29 PM
In my experience everything does not sit on top of the lead. Of course, the condition of your alloy is a consideration but you can still try this yourself: remove whatever is sitting on top of your melt then stir the melt with an edged dry wooden stick (which is itself a flux), scraping the sides and bottom of the pot, and see what shows up.
While I don't exactly blend whatever flux with the lead I do inexactly increase the effective contact area by stirring.

Cord
11-24-2010, 08:32 PM
Stirring and scraping are mostly a physical process,
even when done with a wooden stick.
Fluxing, done correctly, is also a chemical process.

When whatever you use as a flux starts smoking,
you should light it off with a grill lighter or long match
and let it burn, standing back from the flames and smoke.

The flames consume the carbon in the flux and the
oxygen from the oxides in the dross, (and the air)
returning the oxides to their metallic state and into the melt.

You could probably recover a surprising amount of metal
From your dross if you haven’t thrown it away.

.

lwknight
11-24-2010, 09:10 PM
It is a lot if work and hassle to recover all the alloy metal when smelting.
Here ' s an example: I had 225 pounds scrap lead. I knew that there was a certain amount of plain dirt in it. After melting it and skimming a lot of thick heavy crud off the top , I weighed the ingots. There was 30 pounds missing.

So I looked at the crud that I had skimmed off and there was still a lot of lead in it. Well you can't help but to toss some good stuff when smelting junk. Anyway I took the crud and put it back into the pot and covered it with the lid and heated it to whatever temp it would get to in 45 minutes. Then tossed in a large chunk of wax ( golf ball size) and smoke and flames were impressive. I covered it back up and let it sit and cool a bit and then stirred and worked the crud with some unburned wax still in it.

The result was that I recovered about 15 pounds of good lead from the scrapings. I have been saying for a long time that you can work and smash the floaty junk violently and with intent and most of it will reduce back into alloy , leaving only dust. This really is a lot of hassle when you have a large batch to smelt though.

The dust that you scrape off the sides and bottom is already separated from the lead. The only thing that you are actually doing is to get it out of the pot. It will not mix back in but , will be a hassle to dip around without having to skim the ingots too as you pour them.

Tom-ADC
11-24-2010, 09:24 PM
well i guess it does matter

Mini14 I see your avatar us US Border Patrol my son in law retired June of 2009 with 32 years of service, He was attched to Campo station in San Diego county, plus a place in NM as a driving instructor.
My hats off to you guys, thanks!
BTW I flux with beeswax.

Bret4207
11-25-2010, 09:38 AM
This is why I like using a stick rather than waxes, oils, etc. Get the stick into the mix and stir and scrape. The stick is charring, the scraping is putting the carbon into the mix below the surface and the physical movement of the alloy seems to help to both free the impurities and reduce the tin/lead oxide back into the mix.

There's more than just having smoke and flames to fluxing.

44man
11-25-2010, 10:43 AM
Try to solder without flux! Fluxing combines the metals back into the alloy.
Bottom pour guys use stuff to keep oxygen off the surface of the melt.
I don't know much about metals but think oxygen breaks the bonds and fluxing removes oxygen molecules.
However, there is crud that sinks in lead and you will see it all if you pour out the pot. Nothing will float that stuff. That is what messes up a bottom pour spout.
Even wax that is burning on the surface is stirred into the melt with a spoon to react. Don't just let wax burn, stir it in. A wood stick works great.

stainless1911
11-25-2010, 12:53 PM
so, should I plan on cleaning the pot by draining it out now and then? If so, how often, and what would be the best method to clean it?

HangFireW8
11-25-2010, 04:47 PM
so, should I plan on cleaning the pot by draining it out now and then? If so, how often, and what would be the best method to clean it?

How often depends on how fast it gets dirty. That depends on how clean and well fluxed your ingots are.

As for cleaning, scraping is the only thing that works for me. There always seems to be sulpher clinging to the sides, but it is easy enough to remove.