Stratification

[Drm50]

I've been casting bullets,fishing tackle, toys for fifty years. I have melted a lot
lead that I didn't know what alloys were in it. I was on another forum and
mentioned the lighter metals will form in layers on top of the lead. I have
experienced this more than once when melting down asst. scrap. I think the
top layer was Zinc, but not sure. Any way bullets will be fine until pot gets down
3/4, then bullets will be brittle. If thrown on floor hot they will break easy, and
they are much lighter than lead. Has anyone else had this happen and know the
Technical name for it. Guy has bugged me to point of calling me liar/ fool. I found that when melt is fluxed & stirred, then cast into ingots, metals will not
separate in second melt. I don't know the weight of lead, I use 6qt Dutch
oven for primary melt before pouring ingots. Melt with a propane salamander.
Need expert terms!

 

[GP100man]

What`s the temp of your melt???

Tin/antimony/monotype will separate when super hot , maybe approchin 1k f

Zinc will look like oatmeal on top of a melt at 700f as zinc melts at 787f

Some have successfully skimmed zinc off with a sulphur fluxing .

Zinc is a good bit lighter than lead & most tire shops have/are changing over & keepin the smelting (melting wheel weights in bulk) to 650-700 will let the zinc/steel weights float to the top.

No more lighting the fire & let er roll , times for the caster are changing!!!

More readin than ya can do in a month on this subject over on
CastBoolits.com

GP

 

[snuffy]

Sorry to have to tell you this, but lead alloys do not separate out in layers. That's an old myth that gets repeated so often that it's accepted as fact.

Lead, tin, and antimony become a solution or homogenous mixture that cannot be separated at the temps we use while casting bullets.

What can happen at higher temps above 750 degrees, is oxidation of the 3 metals on the surface of the melt. Tin is much more easily oxidized, it will form a thin scum/dross if left at 750 or above. Simply fluxing the molten alloy often, re-combines the tin and returns lead and antimony oxides to thee metallic state.

Any agitation of the molten alloy, like using a ladle, or dumping sprues back into the pot as you cast boolits, will result in more rapid oxidation on the alloy surface. Using a bottom pour furnace/pot will minimize that. Also, using sawdust as flux, then leaving the charred remains on the alloy surface, will insulate the surface from the atmosphere.