daniel on tue 27 jul 04
Hi All,
I have a question about a tenmoku glaze I just got back from a cone 10
redux firing.
On one piece I notice a funny blue crystallisation. There was a certain
amount of crystallisation (tea dust ? ish I guess) most likely due to the
hour long soak at top temp. Anyhow, that's fine. What's odd is the blue
crystals. The surface is matte to the touch and most pronounced where its
thick. I had a dozen or so pieces glazed with this tenmoku with some brushed
on wood ash high up. Some exhibit this problem, but its not clear that all
do. Its very faint on some. I'm not sure the wood ash is responsible as the
place that the blue occurs is not surrounded by the characteristic honey
colour I get from wood ash on this tenmoku. Its way down the bottom where
the glaze has rolled a bit. The hour long soak at top temp is new - could it
be implicated.
I have put a full report with photos and recipe on my website, as this
seemed easiest. The URL is http://www.clayosmos.com/tenmokuQ.html . If you
have any suggestions as to the nature of the blue, or what I might try to
repro. it or not, please let me know. One thing I should probably 'fess up
to is that I also had a test tile with this tenmoku on it with about 2%
cobalt added to it. I did not load the kiln and do not know if the tile was
anywhere near this piece. Could the cobalt have fumed and done this if it
was ?
Any ideas will help me try to direct future tests. As its at a rec. centre
studio where I take a class I have limited control, but I can try stuff.
Thanx
D
Belmont, California, USA
(ex terra australis)
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