Ivor and Olive Lewis on sun 21 sep 08
Having fired a blend of ingredients that would provide the oxide
analysis of Egyptian Blue I was left with a hard opaque black residue
in the crucible. My only modification to composition was to
incorporate 10% Sodium Carbonate to encourage faster sintering and
possibly complete melting.
The solid mass did not wish to detach itself from the ceramic crucible
so I put the whole lot in a dolly pot and gave it a brief pounding to
create as little damage as possible then dressed the ceramic from the
sinter/melt with a hammer. Selected fragments were then pounded to a
powder. Everything still seemed to be black.
Examination under the microscope gave an image of larger and smaller
fragments. Small fragments were of three distinct types.
1 Needle shaped transparent colourless crystals.
2 Irregular dull green transparent fragments.
3 Black opaqued irregular fragments.
Large fragments.
These were dull green, transparent on thin edged to opaque with black
opaque inclusions. Some inclusions were rectangular in form, others
had a rhombic profile.
In the field examined there was no suspicion of Egyptian Blue, only a
neutral green.
Should anyone wish to subject this substance to X-Ray analysis I could
provide a gram sample.
Ivor Lewis.
Redhill,
South Australia.
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