Talk to me about what forms on the top of the melt...

[Rick]

Don't ever poke the stick deeper than halfway to the bottom. Use an SS teaspoon for scratching around below that.

Or better yet don't use a wood stick at all. When that became a big topic over on CB I tried it with paint stir sticks. I tried it once, never again. The melt is plenty hot enough to char the stick, it won't burn because there is no air under the melt but it does char and bits of charred wood do break off and they do become trapped by the density of the lead. They will end up in your ladle or in the spout when bottom pouring.

Proper fluxing is not trying to force anything below the surface of the melt, not a stick and not sawdust. Proper fluxing is bringing the alloy up and pouring it through the sawdust.

 

[JWFilips]

I know When I started out I had all Kinds of issues in my bottom pour: between the advise Of fiver & Ian (They thought me oh so much!) No Sticks near the bottom...so oxidized Sprues back in the pot! I do all my scraping with a homemade stainless ruler tool. I do not add any type of wood into my casting pot ( that is only for clean smelting)
Like I said I always seal my melt with a chunk of Bees wax. It will form a black crust in time. When i'm down to 1/3 pot I clean that off and add fresh ingots ( but don"t drop them in I nestle them onto of the melt with a spoon one by one so the cold alloy doesn't sink to the bottom an pull any junk down with it !)

 

[Rick]

That's interesting. If you only put the wood stick half way to the bottom it won't char and nothing will flake off of it. Interesting indeed.

 

[KHornet]

I have had small pieces of charred wood come to the surface, to be skimmed off. I also use a spoon to scrape around the bottom. It just works for me, not recommending it to anybody else.

 

[Ian]

I think of a wooden stick as a sort of "magic eraser" for the kling-on dross and powdered oxide junk that always seems to coat the sides of the casting pot as the level goes down. Before filling, I rub the end of the stick up and down the sides, clean off the valve pintle rod, and go around the edge of the remaining melt until everything is nice and clean. Then I scrape the bottom and bottom sides of the pot with a spoon, stir to bring up the submerged stuff (usually little to none), then skim all the debris away before adding ingots. I add ingots with tongs very carefully similar to how JWP does it so I don't carry scum to the bottom of the pot on the end of the ingot.

One time I had some WW metal in ingot form that someone threw in on a trade deal. The ingots had a dark grey color to them and were extremely hard, so I was suspecting of them. Finally I tossed them into a clean casting pot to see how they acted when melted. I kept getting clotty oatmeal and bullets didn't want to fill out, but it didn't quite act like zinc contamination. I even added a little solder to see how that worked and it didn't help. So I took some sticks split from yellow pine boards and poked them into the melt about halfway and stirred slowly. The bubbling action of the moisture gassing off underneath really broke loose some junk, after two sticks and maybe five minutes I had this grey fluffy stuff on top that looked like burnt aluminum foil and clean alloy beneath. I skimmed the junk and the alloy cast perfectly. Never would have gotten that junk out if I hadn't put the reducant/flux down into the middle of the molten metal where it could do some good. Sticks are just another tool in the caster's toolbox. With all the various and often unknown metals some of us try to make bullets out of, we need every trick we can find.

 

[62chevy]

Awesome info guys !

I ladle cast and keep a small amount of saw dust in the pot to help reduce oxidation. I move it around the pot and then to one side then I scoop some lead and pour it into the molds.

 

[Kevin Stenberg]

Again. I learn from the minds of masters

 

[Brad]

I wonder if the black stuff is residue left from the boric acid over time. Stuff that heats up with the and causes the residue to get worse.
I would seriously consider draining the lead and adding water to the pot, plugging it in and letting it boil for a bit. Scrape the inside well while wet and set if you can get most of the residue out.
Over time we all get oxides forming, it is the simple reality of hot liquid alloy and air reacting. What I don't get is a layer hard enough to bridge across the pot and remain suspended above the alloy. That sounds like a worse case scenario. Might be crud built up on the inside walls of the pot held in place by box acid glass coming to the surface over time.

 

[JWFilips]

Brad,
I have seen references to cleaning out an empty pot, by boiling water in it, a few times (on the other side of the street). I haven't done it myself because I can't see what could be in that crud that would be water soluble?
Anyone care to further ellaborate to explain how this would work? When I get around to cleaning my bottom pour I usually "suit up" Don a mask and have at it with a wire brush!
Jim

 

[fiver]

the water just is a way to keep the dust down, it also does pull some gunk off the sides/bottom of the pot.
but it mostly allows you to get in there and scrape/brush everything clean.

you know I ain't ever really cleaned my casting pots.
[I did turn over my LEE 20lber once and whack it a couple of times when I was using it to melt ww's down for shot making back in the day]

I just keep clean lead in them, keep them full, and scrape the sides and such.
I do however clean my alloy a couple of times before it ever gets in them.
just making up a big batch of ww alloy the way I do it would seem like unnecessary work to most everybody else.
but I got what I got and I got a lot of the exact same alloy to work with.
that way the only thing I really ever have to deal with is oxides [for the most part] and a flaming piece of candle/bees [or vitaflux] wax or some pine resin deals with that in short order.

 

[RicinYakima]

I retired two years ago as an Environmental Chemist, mostly doing drug lab cleanups. About 15% of the solids from wood, greases, etc., used as flux finally decomposes into inorganic salts, almost all are water soluble. Think of calcium carbonate and sodium phosphate as common ones. They stick to iron very well, and while all the solids in your pot are much less dense than liquid lead, it forms a crust on the surface. Usually the coils only cover the middle third of the crucible, so the bottom of the pot is the coldest part and builds the most crud.

Since I empty my pot every time I use it, when it cools I can just pour a little water in it and wipe it out with a paper towel. Prior to 1995, my Lee ten pounder had never been clean since I bought it in 1974. I took a couple of boiling to get it down to stainless again. Lead melts quicker and you use less electricity with a clean pot.

Remember, casting lead is an art form, not a science. There are many ways to do things, so do what you wish. Only the end results matter, making a perfect lead bullet from the mould's cavity.

FWIW, Ric

 

[JWFilips]

Ok , Understand now. I will give that a try next time I need to clean my pot. Better then suiting up in Hazmat gear.
It actually has been awhile since I cleaned my pot now that I do one large smelt of my working alloy & super scrub it ( From what I learned from Fiver, Ian and that other guy over there, "Duke in Maine ...now in Florida! He did write up a good article on scrubbing the smelt) anyway now only good clean alloy goes in my bottom pour and it has really made a difference...Like fiver said "Only have to deal with oxides"
i usually try to do one big smelt in November up here. That gives me plenty of clean ingots to cast with over the winter & early spring and keeps me shooting Spring , Summer and early Fall.

 

[James W. Miner]

Jim, your not paying attention. NOBODY has said the alloy separates. NOBODY! Separation as your talking about does not occur. However . . . Separation and oxidation are two completely different things and Oxidation DOES occur.

You are entirely correct and sorry if I sounded funny but I have read for years about those that remelt what they skim. I have also read forever about losing tin and antimony.
Now if you get zinc by accident, you can remove most of it. keep the melt at 600° or just below and skim the oatmeal off. Do not flux or it will go back into solution.
I don't know if the zinc will drag along any good metals but to get rid of it is still better.
Why would anyone worry about oxidation on top if you bottom pour? Kitty litter and sawdust or some flux. Just a simple flux to try and get crud up to the top should be all needed but I will never understand why the stuff on the bottom will not float even if stirred and fluxed.

 

[Ian]

Best I can figure the stuff on the bottom gets trapped between the surface of the melt and the surface of the pot. Lead alloy and especially low-tin alloy or pure-ish lead have a very, very high surface tension that's tough to break. Like water bugs that can literally walk on water without breaking through the surface, contaminants that get poked through the surface on the bottom by stick/spoon or carried there by solid sprues/bullets/ingots added to the melt tend to be held there by the surface tension and weight unless you can coax them to the bottom corner and up the side with a spoon. Otherwise, the junk follows the flow of the metal toward the spout and ends up in your bullets. If you can keep from touching the bottom of the pot, nothing will ever get down there....but if you drop in a bullet it will sink, break through the bottom surface tension and leave part of its oxide skin outside the surface tension of the melt when it melts. The lead alloy oxides cannot melt at casting temperatures, they must be chemically reduced to free the oxygen and turn them back into pure metal form.

 

[JonB]

I empty the pot after each use...spooning the dross into a soup can.
So, the next time I cast, after filling the pot with alloy and scraping the sides clean, first with charred stick, then with SS spoon on bottom and sides. I leave all the dross and oxides on the melt, and then I'll add even more Dross from the soup can, so I have about a 1/2" layer, for heat insulation as well as an oxygen barrier, and topping that with a sprinkling of sawdust. While I never add sprues back into the melt while casting rifle bullets, I will when casting pistol bullets. The thick dross layer will float the sprues and the theory is, they melt back into the alloy and the surface oxides stay on top.

 

[Rick]

contaminants that get poked through the surface on the bottom by stick/spoon or carried there by solid sprues/bullets/ingots added to the melt tend to be held there by the surface tension and weight

Plus the density of lead will also suspend oxides, dirt etc. that you would think would migrate to the surface. Reality is though that not all does or can.

 

[Ian]

Exactly, Rick. I was trying to think of an analogy for that to put in my last post, dry grits suspended in pancake syrup was what came to mind. Even though the grits might be less dense than the syrup volume-for-volume, they won't float to the top because the syrup is too viscous. Same thing with dust and dross trapped within the melt. That's why I like to poke a stick down in there and boil that stuff out. I know it puts ash in the melt, but the overall action of the bubbling/steaming of even the most "dry" stick seems to take care of it's own ash plus a lot of other gunk. Might be my imagination, but it seems to work.

 

[Rick]

Bottom line is that however you consider correct fluxing if it's working for you and your satisfied with the results your certainly doing it right for you. In bullet casting there is no ONE right way for most things.

 

[RicinYakima]

Ian, I think your analogy is absolutely correct. The surface tension is so high that the melt can not "wet" the solids that form. You could also think of it as the weight of the melt is holding the solids against the crucible walls. When the bottom pour spout is opened, the weight / mass of the melt drags the solids with it. That is why I ladle pour rifle match bullets, bottom pour pistol bullets from the RCBS and if a match mould requires bottom pour, I use the little 4 pound Potter.

 

[James W. Miner]

It all sounds good to me now.