Curiosity question - getting towards the bottom of the pot

[FISH4BUGS]

If you take, for instance, a Lee 4-20 and load it up to the top, and basically empty the pot by casting, as you get towards the bottom of the pot does the alloy change at all?
I stir and skim as I go as needed. So as dross is taken away, what is left is ........
Just curious.

[Dusty Bannister]

Less of what you started with. It all oxidizes. The alloy remains the same.

http://castboolits.gunloads.com/archive/index.php/t-15149.html

[RickinTN]

If the mix is fluxed properly before you place it in your casting pot nothing should be skimmed off. The mix does oxidize as you go along. This would need to be reduced back into the melt. Sawdust, leaves, and many other thigs are good for fluxing. They will remove valve stems, gravel, broken or not broken bolts etc. from your mix. Once this is all removed nothing else to remove. Wax is excellent for reducing a mix. This is when all the oxidized metals are reduced back into the mix. Again, nothing should be skimmed off of your casting pot other than the carbon left from the wax when used to reduce the mix.
Rick

[jsizemore]

We did a test on this a while ago. Lots of alloy old and new. End result was (thanks to the exhaustive work of BNE and other members) you end up with what you started with. The little you scrape from the top makes little difference if any.

[fredj338]

I never drain my pot or let it get less than 1/3 before adding alloy. This keeps it form dripping for me.