What is this sludge? And why is my lead breaking like cookies?

[Stopsign32v]

Trying this from my phone so I hope the pictures show up. But best I can describe this is heavy sludge. I flux with sawdust to get a glass like top to my lead pot but in doing so I remove this heavy sludge. Just going by weight I can tell I’m losing a good bit of lead which makes me sad. Is this needed?

Second question is lately I’ve been noticing my lead on top of the sprue plate is fracturing apart in pieces rather than being a solid mass of lead. I also noticed one of my boolits had a crack in it. Looking at the fractured lead from the plate best I can describe it is the inside looks like powdered metal. My hardness right now is at 10.4 BHN

[ih772]

Zinc contamination?

[JonB_in_Glencoe]

What alloy?
what temp?

It doesn't look like Zinc contamination to me, maybe you are running your pot too HOT?
...Zinc contamination looks like Oatmeal and as soon as you remove the Dross, more forms...unless you crank the temp real high...like over 800º high.

[Cap'n Morgan]

I have quite a stash of tin-based babbit metal - about 80% tin content. When melting, it will form a sludge in the transition phase, somewhat similar to your pictures.

[Dusty Bannister]

Your photo shows the thermostat setting at the highest position. It appears to be a relatively new pot, but may have scale build up if you failed to clean your alloy in a different pot. You mention saw dust, but do you also use a wax or perhaps other type of flux to help clean the alloy? It might be helpful to ID what you think your alloy might be. If the alloy temp is excessive, the sprue will take longer to become solid so it will fracture while still mushy. Same with the bullet if you are casting long skinny bullets. That information might be beneficial.

When you add candle wax, expect it to flash ignite so use care where you do this.

[mehavey]

Do youself a favor... flux with candle wax* as above... not sawdust.
Bet you will find a world of difference


*
(even better and pea-sized lump of 50-50 ALOX/Beeswax bullet lube)

[Rcmaveric]

I couldnt tell what temp you are at. Some alloys get a grainy transition stage specially those with antimony. Raise the temp to 800*F and flux with wax (bee, candle, wifes stash of smelly goodie).

Sent from my SM-G991U using Tapatalk

[Bent Ramrod]

Yes, try the candle wax, and keep stirring until that crusty stuff has disappeared and any impurities are no longer clumped, but look like loose black dirt.

I set the smoke on fire with the candle, and let it (held in one hand, horizontally) continue to burn and drip while stirring with the other hand. If the smoke stops burning, I relight it with the candle; if the candle goes out, I light it off the burning surface of the pot. I stir until I get a mirror surface with black specks.

The black dirt I wind up skimming off has a minimum of metal in it, and it looks like smooth metal, rather than that oatmeal consistency your pictures show. If you had zinc in it, the whole pot would look like that; an uncastable slush that never fully liquefies.

[Baltimoreed]

What Bent Ramrod said. ^^

[Springfield]

You really need some sort of thermometer.

[zarrinvz24]

I use a small marble's sized chunk of paraffin wax, put it on top, let it melt on top and then stir it using a wooden paint stick. It will smoke a lot, and if you use too much wax it may catch on fire.

[mehavey]

stir it using a wooden paint stick.

Since I dipper-pour, I just run the dipper upside down to
the bottom of the pot and back to get the liquid wax all
through the melt. Rarely do I wind up w/ anything but
sooty dross left on top to scrape out with a teaspoon.

[dkf]

I find sawdust doesn't cut it for flux a lot of time. So I am not a fan of it. I get some of that separation on some of my alloys and add some candle wax from an old candle I have, mixes it right in. Makes good bullets then. Mine doesn't have zinc in it, I know that for sure. What I end up removing from fluxing is not the color of lead or tin.

[MOA]

Sawdust flux burned black and ready to be removed.




After removing all the burnt sawdust and after fluxing with pariffin.

[ShooterAZ]

I use sawdust and paraffin wax when smelting, works great. I only use beeswax in my lead pot though, it's much cleaner. It's kind of difficult to pin things down when we don't know what alloy you're using or the source of your lead. I'm also guessing that you're running it too hot.

[414gates]

Looks like tin on a cold melt.

The first time I melted down scrap, I got that, and I unknowingly scooped it off. It was with my prototype melter, and the heat output was too low.

Later on I realised the melt was too cold for the tin to go into solution, so it floated out.

Not sure what the power output of those little electric units are, but you'd do better with it if you kept it half full. It takes a lot of juice to keep all that lead at temperature, maybe more than the melter can handle with a full pot.

[oley55]

I'm with the "too cold" crowd. I bet most of it can be fluxed back into your melt, so don't throw that dross out yet.

[Stopsign32v]

I'm with the "too cold" crowd. I bet most of it can be fluxed back into your melt, so don't throw that dross out yet.

This makes sense I think.

And in the pictures the temp is set at 7, not max. Max is 9

[charlie b]

Yes, that is probably tin. I will sometimes see that same kind of thing as the pot heats up. Leave it all alone until your pot is well up to temp. Then flux it. I initially use beeswax, then put a layer of sawdust on it to keep oxides from building up.

[Stopsign32v]

So would you guys add the sludge back into the pot, up to temp, and then flux? I finally have the BHN where I want it so if I add this what we think is tin, my hardness will go up (which I do not want).

Should I toss it or keep it for future use as tin? (assuming that's what it is)