It’s just the casting core made from clay, charcoal and probably some organic material. I think it was stored in a humid enviroment. If you have the patience you can try take the core out with a thoothpick. I don’t think you can rinse it away with water because rhe clay etc is baked during the casting process.
You can also try brushing the gray surface away, but wear a dust mask. Its possible the greyish material is a kind of fungus.
I'll try both of your suggestions. I would prefer "empty" rings! :-)
First, I tried to poke out the black insides. You're right, it felt like sandy clay, and no amount of poking had much effect.
Okay. So how to clean the gray crap off? I took Han's warning about how it might be fungus.
So I put a few beads in a bowl and added boiling water.
Yay! All the white stuff is GONE!
And the black insides now look a lot better.
Another batch in progress this morning.
Thanks again, Hans!
As you know the African Brass/Bronze Lost Wax bead method often involves carefully piecing threads of wax over a clay core- especially the hollow "filigree" looking beads. The wax bead construction may be coated/dipped first in several slurries of (charcoal &) clay and then packed carefully in clay which will make the outer one time mold.
EDIT- I should also add that the wax is removed by heating leaving through ports, and that the brass/bronze is then poured into the casting shape left by the wax through a hole or holes. The inner bead clay core remains at that point in the center of the bead. Oversimplified version..
Usually this inner clay core is broken up and expelled after the casting is cooled (?) and is broken open. You have to ask WHY the clay core did not break up? Why was the core retained? Was it a "bad" clay that solidified too much, and maybe had some extra and unusual mineral content (which may account for the white precipitate).
I do see some other similar Igbo Lost Wax Brass/Bronze beads that are retaining the clay core in a similar manner, though not turning white.
If you have a diamond tip bit for Dremel type drill are you able to clamp down a bead or two and drill the white/black core out? Is it too hard all the way through? Does it begin to break up at all? I think the odd composition of the clay core material is what is at the root of the problem.
