Marianne Lombardo on wed 11 sep 02
Raw Sienna from Mastering Glazes book by John Hesselberth/Ron Roy
^6 oxidation, slow cooled firing
Tested on Tucker's Mid Red, Mid Smooth Stone, MCS, Mid Cal 5
In the bottom of the kiln where cooler, the test tiles are matte glittery
dark coppery color
On a bowl in the middle of the kiln, glittery dark coppery color, with some
shiny darker brown where pooled in
crevices. This positively sparkles in sunlight.
This is the second time I've tried this glaze. My results are darker than
the photo in the book, for some unknown reason. And I have no idea why it
glitters and sparkles like gold when the sunlight hits it. I suspect it has
something to do with crystal formation.
John or Ron can you comment on this phenomena?
John Hesselberth on wed 11 sep 02
Yes, you are probably seeing reflection off some of the crystals. This
glaze is quite dependent on slow cooling. You obviously are in range;
however it you cool it even more slowly (say 50F/hour from 1900 down to
1500 it will get more matte and more uniform as the crystals become more
numerous and/or larger. Personally I prefer it more in the range where
you currently are working. The darkness is probably just due to
different lots/purities/particle size/whatever of your RIO vs. what I
used--or your different rutile. If you are also using Tucker's rutile I
have seen that it is quite different--not better or worse, just
different-- from what I use.
On Wednesday, September 11, 2002, at 09:29 AM, Marianne Lombardo wrote:
> My results are darker than
> the photo in the book, for some unknown reason. And I have no idea why
> glitters and sparkles like gold when the sunlight hits it. I suspect
> it has
> something to do with crystal formation.
> John or Ron can you comment on this phenomena?
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