Stephani Stephenson on thu 12 oct 00
Dennis
I too have some red iron oxide that behaves in the same manner as you
describe.
It is much more brown than red and does not dissolve. However this batch
is very old. It is still in the original paperboard cylinder . I
would guess it is 60 -70 years old, judging by the appearance and
address( pre zip code) and phone number ( a few letters a few numbers)
on the cylinder label
I had always guessed ( and it was just a guess), the changes in
solubility and color were due to the aging of the material, though
whether those changes occur on the granular level or molecular level, I
don't know. Or perhaps it has something to do with the original
processing of the ore or the deposit. A good question.
I also have a jar of some 'umber', a dark brown staining oxide which i
would guess has some iron and manganese in it, but also seems slightly
oily, does not mix with water but stays suspended and dry on the
surface. Don't know too much more about it, except that it has very
very strong staining properties.
When I use these I just dry mix them first with other ingredients, or
add them to an already viscous glaze batch
As long as I'm on this, I also have some cobalt oxide from that same
era...very black , very strong and two old bottles of lusters, one
platinum and one copper. The lusters have never been opened and the
bottles are exquisitely sealed with paper, wax and string. The liquid is
still there. Would anything happen to these over time? chemistry
wizards? would they have any value?
It is sort of fascinating to see how these supplies of yesteryear were
packaged and distributed. It seems that many of these oxides, stains
and lusters were purchased by the potter from the local pharmacy.
Stephani Stephenson
Leucadia CA
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