John Hesselberth on thu 26 may 05
For those interested in this pottery and the glazes put on the pots, I
just ran across a treasure-trove in a book I had not been aware of. It
is "Seto and Mino Ceramics: Japanese Collections in the Freer Gallery
of Art" by Louise Allison Cort. It was published in 1992 and is no
longer in print, but I was able to find a copy through the normal
used-book dealers. Turns out the copy I got was brand new. I found this
book after a careful read of Jim Robinson's Studio Potter article on
Shino glazes. It was one of his references. Thanks Jim!
Anyway, in addition to having quite a large number of both color and
black and white photos, in the appendix it has 4 pages of analyses of
glazes--about 30 glazes in categories of Seto ash-glazed; Mino ash
glazed; Mino Shino ware from 3 different kiln groups; Mino Oribe ware;
and Mino Ofuke ware. The glazes were analyzed from sherds by
Wavelength-Dispersive Electron Microprobe Analysis. They are reported
in normal oxide wt %s just like the materials analyses we see.
I am one of those people that prefers to look at unity numbers, but it
is quite easy to convert the wt%s to unity with the help of glaze
calculation programs. I don't know how they all work, but I had to do a
little work-around in the one I use. First I entered the standard
oxides as materials in the materials database. Of course the
compositions were easy, e.g. alumina is entered as 100% alumina, etc.
Then enter each of these glazes as a Recipe using its oxide contents as
the ingredients. Unity is then automatically calculated. Of course if
you want to go the next step, most programs offer some help in going
from a desired unity formula to a recipe which you can construct either
out of historical materials--if you have the analyses-- or materials
available to you today. That process is usually called "Formula to
Recipe".
Now whether or not all this would allow you to reproduce those glazes
is highly questionable. Impurities, firing conditions, etc. would also
have to duplicated. But I was just fascinated to see all these analyses
which would certainly be good starting points for anyone wanting to do
research on glazes of these types.
Regards,
John
John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com
Lee Love on fri 27 may 05
John Hesselberth wrote:
> Now whether or not all this would allow you to reproduce those glazes
> is highly questionable. Impurities, firing conditions, etc. would also
> have to duplicated. But I was just fascinated to see all these analyses
> which would certainly be good starting points for anyone wanting to do
> research on glazes of these types.
A very important aspect is the particle size of feldspar used for the
glaze. It is coarse. Because of this, many of the pinholes, crazing and
fissures are apparent right after dipping the glaze, before the firing.
Folks are experimenting back home (and here too) with rock crushers and
local stone. I am excited to find out what they discover.
--
李 Lee Love 大
愛 鱗
in Mashiko, Japan http://mashiko.org
http://hankos.blogspot.com/ Visual Bookmarks
http://ikiru.blogspot.com/ Zen and Craft
"With Humans it's what's here (he points to his heart) that makes the difference. If you don't have it in the heart, nothing you make will make a difference." ~~Bernard Leach~~ (As told to Dean Schwarz)
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