iandol on thu 9 jan 03
Dear Friends,
I recently fired mixtures of Silicon dioxide and Barium Carbonate which =
would give me the necessary ingredients for Barium Metasilicate and =
Barium di-silicate. These mixtures were fired to Orton Cone 8, about =
1250=B0C.
Both samples sintered into hard masses which required the 'Dolly Pot and =
twenty pound pestle' treatment to reduce them to a powder.
Tested with acid there was no reaction. This indicates that the Barium =
carbonate had decomposed. Effervescence would have told me that the =
Barium carbonate had not decomposed.
Powdered samples of each were mixed with pure water and tested for pH.
Both gave a very strong alkali reaction suggesting that, even if a =
reaction had taken place between the Barium and Silicon oxides that =
Barium oxide was present in the sintered mixture. Aqueous digestion, =
filtering and weighing will tell me more.
I am now suspicious about the stability of High Barium Matt glazes, with =
or without Copper being present, even in contact with plain water.
Next stage is to test the samples of high Barium Transparent samples and =
see if they give a similar reaction.
This may get interesting!
Best regards,
Ivor Lewis. Redhill, South Australia.
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