Lewis on fri 15 may 98
>----------------------------Original message----------------------------
>Dear Clayart,
>
>I am interested in a number of Japanese glazes...(text snipped)
>Sincerely,
>Alex
I think you would appreciate the book _Hamada Potter_ by Bernard Leach;
Kodansha International, Tokyo, New York, London; first edition 1975; first
paperback edition 1990; ISBN 0-87011-828-5. The paperback edition is still
available.
"Kaki glaze (persimmon red) is one of the traditional Mashiko glazes used
on the standard kitchen ware. It is made from a soft stone used for
building...we only mix the powdered stone with water to obtain the kaki
glaze. By adding 20 percent wood ash a wonderful tenmoku is obtained...If I
add more ash (about 40 percent) or transparent glaze to the kaki, it makes
ame, a greenish brown, slightly transparent, syrupy glaze." (p. 201, Hamada
Potter)
Nuka glaze is made with a different stone and two types of ash. Hamada said
the following on the making of glazes:
"In addition to a clay body, if you have volcanic or feldspathic stone, or
a type of china clay and ash for glaze, you can make pottery. We must not
allow ourselves to complain of the lack of variety or quality of materials.
Instead we must learn how to make full use of given natural materials and
processes. Fine white porcelain, celadon, or temmoku were made just because
such materials were available in that area without spending any special
effort. Clay, form, and glaze were perfectly integrated. But later copies
of these pots made in other countries have a cold empty, calculated feeling
no matter how technically competent the potter is. This fact is so plain
that very skillful potters often fail to recognize it.
....Out of two materials you can make a nice glaze. Take a finely ground
volcanic stone. Add 20 percent black wood ash...for your first test. Many
mixtures of finely ground stone will melt if they are fluxed by the
addition of ash.It is simple to test how to use the raw materials in one's
own area. First, experiment with ash and stone in eleven combinations. The
first...will be no ash, and stone only, the second will be one part ash and
nine parts stone...and so on to the eleventh experiment, ash alone. The
type of ash used plus the iron content of the stone will produce many
variations. The same tests should be made with ash and clay.
I would fire these different glaze tests to a temperature varying between
1,250C and 1,300C."
(pp. 198-199, ibid.)
I use slip glazes made from three materials: my throwing clay (a stoneware
mined in southern Sweden), local glacial clay (earthenware), and wood ash.
The glacial clay has a composition similar to the Mashiko stone used for
the kaki glaze, and not surprisingly, makes a kaki glaze by itself. When
mixed with increasing amounts of wood ash, the glazes changes from glossy
iron red, to various blacks, to transparent green-brown, and to muddy
green. If I were Japanese, I would say Kaki, Tenmoku, Ame, and dark
Celadon. The stoneware mixed with ash yields transparent, white, and light
celadon glazes. You can, of course, make all these glazes with materials
from a ceramic supplier, but you don`t have to, and you may benefit from
not doing so. That`s what Hamada told me, in any case.
Good luck.
Colin Lewis
Soderfors, Sweden
mc.lewis@swipnet.se
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