Greay crumbly substance on my melt???

[PBSmith]

If I let my 20-pound melt pot get too low, I get significant gray crumbly material on the surface. I could photograph it next cast, but I suspect some of you know what I'm talking about.

As long as I keep a full pot, I don't get the gray crumbly. It's only when I get below 1/2 tank that it appears, mainly by scraping and stirring beeswax into the melt.

I wonder if I'm losing good alloy content here, or this just impurity?

Thanks.

[Namerifrats]

Probably just oxidation, atimony, etc.

[Peregrine]

It's good stuff, flux it back in.

[Conditor22]

I get this when I flux with pine sawdust and wax, this is what I shoot for. I leave it on top of the melt.
It acts as a barrier to prevent oxidation, it also prevents splashes when returning the sprues and helps keep the top of the melt hot (insulation barrier)

https://i.imgur.com/02iH9s8.png

notice the potato masher in the back, I use that to get the flux to the bottom of the melt.
I finish with the whisk the completes the fluxing.

I save it and toss it in the next time I smelt, it helps speed up the fluxing process, not sure I get more lead out but I feel better doing that just in case there is some lead in there :)

[Oily]

My gosh Conditor. That has to be the second dirtiest pot i have ever seen. The other one is mine LOL. I do the same after fluxing my working pot. I don't skim this off the top because of oxidation and you might be skimming your antimony off the top if you do it too much. Great pic of your pot by the way! Did you use a lighting system to get that pic?

[Carrier]

Does it look something like this?

[PBSmith]

Does it look something like this?

Yes, though your salad looks a tad green. What I'm talking about looks exactly like Conditor's potato stew. I don't get this when the pot is full, no matter how or how often I flux.

[Conditor22]

PB flux with both pine sawdust and wax this will help prompt the "potato stew" earlier

[Carrier]

Yes, though your salad looks a tad green. What I'm talking about likes exactly like Conditor's potato stew. I don't get this when the pot is full, no matter how or how often I flux.

Mine was some supposedly pure lead bars I bought from a one time supplier. Needless to say haven’t bought anymore from them.

[CPC24]

Does it look something like this?

I didn’t know you could use broccoli as flux. :)

[PBSmith]

Not that I doubt all the experts on this site, but when I flux with sawdust what I get floating on the surface when I'm done with the stirring is typically . . . . . . burned sawdust and nothing else. It's the beeswax alone that brings up the crumbly crud.

[montanamike]

ive had this happen, before i got a PID. I figured out the lead gets substantially hotter the lower it gets. I'm assuming its oxidizing faster the hotter it gets. It quit happening when I started using the PID. but thats just a guess.

[PBSmith]

ive had this happen, before i got a PID. I figured out the lead gets substantially hotter the lower it gets. I'm assuming its oxidizing faster the hotter it gets. It quit happening when I started using the PID. but thats just a guess.

That makes perfect sense. If this is what's happening, I could be losing good metals from the alloy and I need to watch the temperature more carefully. Thanks for that tip.