Ladle Use when Melt is Covered?

[Racingsnake]

Hi guys...I've read in the "stickies" that it's good to keep the molten lead covered with some sort of flux or wood ash when casting, as it limits oxidisation and keeps the melt at a steadier temperature. This seems fine for bottom pour furnaces but does it apply if you use a ladle for pouring? Doesn't the dross interfere with ladle casting?

Thanks, Racingsnake

[rob45]

Depends mostly on the type of ladle, your particular method of filling the ladle, and how you pour.

When you fill the ladle, it's best to insert it in such a way as to have any trash that does enter remain on top. Your goal is to keep trash away from the pour spout.
With a properly designed ladle, the dross still remains on top while the alloy pours out the side. If you're using a ladle design that makes this difficult, you have to pour slower to give the dross time to shift, and slow pouring introduces its own set of problems.
Also, be sure to use a full ladle with each pour, and never totally empty it.

Just a matter of practice and finding a method that works for you, but it can be done, and is done frequently.

Ideally, the surface of the melt is left undisturbed- an obvious impossibility when ladle pouring. But for many applications we are better served with a ladle, so in most cases it simply means fluxing more often. No big deal there.

[Racingsnake]

Thanks Rob. I'll give that a try. Racingsnake

[geargnasher]

Keeping your pot temp as low as possible for the particular alloy helps reduce the oxide scum formation rate considerably. When ladling, I prefer just to reduce the oxides with sawdust and skim, then when the oxide scum builds up again I stir and work over the alloy with a stick until the stick begins to char slightly, this usually gets rid of the oxides and might leave a pinch of powdery ash behind to be skimmed off with a spoon and discarded, then the ladle is submerged again until hot and casting resumes.

Two important points: When bottom pouring, you can keep sawdust, kitty litter, borate glass, etc. on the surface but you'd better not get any impurities trapped on the bottom of the pot or you'll get "dross inclusions" in your boolits. When ladle pouring, this is far less important but you might want to stop every ten minutes or so and reduce/skim the oxides back in or you're likely to deplete the tin from your alloy. Ladling lead exposes lots of the alloy to oxygen over and over again and increases your oxidation rate astronomically vs. the bottom pour method.

Gear

[376Steyr]

Don't remember exactly where I read it, but one of the old-time authorities (Sharpe, maybe?) mentioned floating an "iron ring" on top of the melt and dipping out of the center of it, clearing the dross only from the center of the ring. Probably not really practical with a relatively small electric melter, and it doesn't address the issue of how often you should flux, but if I was casting from a big iron pot and wanted to use the covered melt method I'd try that. Personally, I use a 1-lb. Rowell ladle with a 20 lb non-bottom pour melter, but only because I got tired of drips and freeze-ups.

[Racingsnake]

Thanks Gear...if I keep stiring the oxides back into the melt will that keep the tin content at an acceptable level?