MOLINA, RAFAEL on mon 21 may 01
Pam and others on the List:
Before I share what Seth said, I have to give a little background as to =
the
source of the question.
One of my former professors, Elmer Taylor, was an apprentice with =
Michael
and David Leach in the early 70's (you can read more about this in my
article "A Conversation with Elmer Taylor" CM September '99.) While he =
was
in England he had the opportunity to meet Michael Cardew.
When I arrived at th University of North Texas as a student in the
mid-eighties this story of Michael living into his mid eighties despite
eating off lead glazed earthenware was one that came up during
conversations, critiques, etc.,... Most probably it came up after =
watching
an old 16mm film version of "Mud and Water..."
Curiously, when I asked Seth his take on the subject the answer was
surprising. Seth said that the earthenware pots were not lead glazed =
(which
I believe. after all this was the mid twentieth century and =
glazing/dusting
pots with raw galena had been out of fashion for some time). He didn't
elaborate further as to the materials in the glaze. I speculate it was =
a
lead fritted glaze, but it may well have been a low-temp alkaline =
glaze.
When I shared with him my experience with lead bisilicate as a powerful =
low
temperature flux which produces a beautiful glossy surface and also =
develops
beautiful color of which my favorites are chrome yellow and copper =
green he
seemed intrigued. =20
From the slide show I gathered Michaels earthenware pieces were thrown,
decorated with slip while wet sometimes with bold finger swiping, raw =
glazed
and single-fired.
That's all I have about the story. Perhaps, other members of the List
especially those in England can shed more light on the subject.
Ciao,
Rafael
Rafael Molina, MFA
Assistant Professor of Art
Department of Music, Art, and Dance
Tarrant County College-Southeast Campus
2100 Southeast Parkway
Arlington, TX 76018-3144
(817) 515-3711
(817) 515-3189 fax
=20
-----Original Message-----
From: Pam Easley [mailto:peasley@QWEST.NET]
Sent: Sunday, May 20, 2001 11:55 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: dardew: true or acropyphal?
Raphael,
Hey, you started the story, and now we=92re all waiting for the =
answer=85=85.
Did Michael Cardew eat off of lead glazed ware and still live to a ripe =
old
age, with no ill effects from it?
Sheesh. No fair. Can=92t start a story and not finish it!!!!!
Pam, in Seattle. It was almost summer today. Clear, sunny, and just
wonderful. My miniature French lilacs just popped a couple of days ago, =
and
the scent is breathtaking.
________________________________________________________________________=
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Janet Kaiser on tue 22 may 01
Excuse the haste, but I am in the middle of a change of
exhibition.
OK, 99% of this list may cast their hands up in horror,
but there is a body of opinion who still say "So what?"
and for whom this is not a problem. Lead has been used
for generations and the lead in a glaze is/was not half
as noxious as the lead content in pewter drinking
tankards or water pipes, which accounts for the high
lead levels in old cemeteries here in the UK and
elsewhere.
Looking at my college notes, all the earthenware
recipes contain either lead monosilicate, bisilicate,
or sesquilicate. This was the mid 1970s, so no doubt
some working potters still use these recipes. Note
Galena and raw lead had more or less disappeared and we
were testing new recipes all the time. One single 'new'
recipe was for a leadless glaze: Borax frit 90, China
clay 10. Add 12% Disperzon or 7% tin oxide for a white
opaque or 18% zinc oxide 4% titanium oxide for a matt
white. Fire 1020-1150 oC. If I remember rightly, this
was one of Harry Frazer's recipes, promoting Potclays
products.
The illustrations or museum exhibits of earthenware
pots by MC I have seen, have been labelled: "slip
glazed earthenware". In other words, once fired as you
said.
Lead was naturally used by everyone producing
earthenware up until very recently and as you can see
from the essay "Slipware and Stoneware" by Michael
Cardew (copyright 1976 Crafts Advisory Committee,
London) below, there was more to his early production
than even he had taken into consideration. See how much
I can get typed before I fall asleep...
"The old pottery at Winchcombe which used to be called
Greet Potteries or Beckett's Pottery, was closed early
in the First World War, and had been lying idle for
about twelve years when I first rented it in 1926.
There was a big updraught kiln of the sort used in
country potteries; the main chamber had a diameter of
about 3 meters and a capacity between 14 and 17 cubic
metres. During the Beckett era it was used for firing
large earthenware washing-pans (which were glazed on
the inside) and flowerpots of all sizes. They also made
bread-crocks, milk pans and cream pans.
During the 13 years that I worked there I was making a
kind of slipware - that is, a soft-fired galena-glazed
earthenware. Galena is pulverised lead-ore (lead
sulphide) and when properly fired combines with the
free silica and clay of the pots, to give a nice
yellowish glaze which is a warm chestnut brown over the
natural red clay, yellow when applied over white slip
or a sort of black if used over a black slip. (Our
black slip was the local red clay with added oxides of
iron and manganese). We did not use the galena by
itself but mixed it with a small proportion of ground
flint (about 10%) and plenty of clay, about 30%, which
enabled us to use it on the raw black-hard pots without
having to give them a biscuit-fire beforehand. If red
clay was used for this glaze it gave a bright yellow
colour over the white slip. When we wanted a paler
colour than the standard yellow we used white clay
instead of read, and this gave a light cream colour.
For green glaze we added five per cent of copper oxide
to the "cream" glaze.
There were only these three glazes, and they all had
essentially the same composition: but owing to the
method of firing there was great range of fortuitous
variations in colour: light or dark, or spotted and
speckled with greens or yellow, or a golden brown like
autumn leaves. Sometimes a patch of greenish colour was
due, not to copper but to local areas of
reduction-firing. Circular markings in a lighter red
colour were often produced by minute particles of
organic matter which were burnt out of the clay during
the firing, giving rise to "holoes" of local oxidation.
We used to burn immense quantities of larch faggots
during the final six or eight hours' stoking. The
poking-in of these faggots and the periodic raking-out
of the mounds of incandescent embers which accumulated
in the ashpits of each of the four "fire-eyes" of
stoke-holes, caused showers of uncontrolled sparks and
fly-ash to rise up through the whole of the setting -
it was these conditions which gave rise to the great
variety in the colours.
It is sometimes stated that at Winchcombe I revived the
English slipware tradition; but the credit for that
belongs to Bernard Leach during the early years of the
Leach Pottery at St Ives. What was special at
Winchcombe was that we were making slipware on the
scale of a real country pottery, in a kiln of the
traditional size and design. But the kind of slipware
which we made was rather different from the
slip-trailed, 'combed' and 'feathered' pots and dishes
of the Midlands tradition which flourished to the end
of the 17th century and beyond. Ours was based rather
on the sgraffito-decorated ware of North Devon, which
is essentially a 'southern' style. Its nearest
relations, in technical terms, are to be seen in early
Byzantine and Islamic sgraffito wares, or those of
Southern Europe and the Mediterranean Coasts.
My own ambition was not to revive any particular style
but simply to make pots which could be used for all the
ordinary purposes of daily living, and to be able to
sell them at prices which would allow people to use
them in their kitchens and not mind too much when they
got broken. This implied that they must be made in
appropriate quantities and fired in a big kiln:
obviously a one-man, studio-scale operation would not
be suitable. It was fortunate chance that Elijah
Comfort, the chief thrower formerly employed by Mr
Beckett, was then still living in Winchcombe and was
able to come back to work in the pottery. With him came
a young boy, Sidney Tustin, who also after a few years
became a good thrower. At firing times, this small
group of three was increased by getting temporary
helpers from Winchcombe, and in the later 1930s our
strength was increased by the coming of Ray Finch and
of Sidney's younger brother. We also had, even in those
days, an occasional short-term student.
I thought at first that slipware was a simple kind of
pottery, which would not be difficult to fire, but I
soon found that galena, as a glaze material, has its
own special difficulties. One of these was the sulphur
it contains. Unless the ware is fired in the open, with
the flames and gases passing freely over it, the glaze
will not melt because the sulphur cannot escape: holes
therefore had to be made in all the saggars to allow
this to happen. These holes also admitted some of the
fly-ash and sparks, contributing to the light and shade
and life of the glazes; but they also sometimes caused
rough or bare patches which made the pots quite
unacceptable in most people's eyes.
A second difficulty with galena was that if the faggots
were damp, or even the pots themselves not fully dry,
the glaze refused to melt: the lead in the glaze seemed
to volatilise, leaving dry areas or a rough surface,
like coarse sandpaper, with an extremely unpleasant
yellow colour, like old, dry mustard.
Another drawback to slipware was porosity. For things
like the big washing pans made in the Beckett's time -
which Elijah Comfort continued to make up to about
1930 - this did not matter so much; but for pitchers
and milk jugs, jars and flower vases, porosity was a
continuing cause of complaints from users, and we had
to try various expedients in our attempts to overcome
it. Earthenware has by definition a porous body as
opposed to stoneware and porcelain, in which the body
is vitrified or impermeable. The way to make
earthenware watertight is by glazing it; but if there
is crazing, water can pass through the network of fine
cracks almost as if there was no glaze at all; and our
glazes were always crazed. The approved way to cure
crazing is to give the pots a hard bisque fir before
the glaze is applied; but this way out of the
difficulty was not acceptable because I realised that
it would spoil the beauty of the ware, the colours and
quality of which depended on using a 'raw' (or 'slip',
or once-fired) glaze, so that the operation of maturing
the body and glaze could take place at the same time,
not separately.
Later on I tried to eliminate porosity by firing at a
high temperature so as to make the body itself
impermeable, even if the crazing was not cured. But I
found that a limit is soon reached to what can be done
in this direction. Earthenware clays usually will not
vitrify properly; they start to fuse instead, become
brittle and may even slump or squat. As the old country
potters used to say, 'The nature is fired out of the
clay'. The pots also lose their fresh, bright colours
and turn a dingy brown".
Faced with the limitations of this kind of ware, I
began during the later 1930s to wish I had undertaken
from the beginning to make stoneware rather than
earthenware. Some of the features of Winchcombe
slipware made during those years show evidence of this
hankering for stoneware: the increasing use of black
slip (partly in the hope that it would vitrify at our
firing temperature), the designs scratched through the
glaze and the underlying black slip to lay bare the raw
clay of the pot, as in some T'zu-chou wares; or painted
in black slip, again in imitation of T'zu-chou. By the
early years of W.W.II, I was feeling that most of the
things I wanted to do in pottery could be done just as
well, or better, in stoneware; many techniques of
decoration are common to both, and some are much more
satisfactory at the higher temperature.
In a time of peace it might have been a fairly simple
matter to move over from slipware to stoneware. But
during the first years of the W.W.II it was becoming
extremely difficult to keep a small pottery going at
all, and to embark on a radical change seemed to be
impossible. In 1942, however, I was able to bypass this
problem..."
Cardew goes on to talk of being invited to Ghana,
where,
"there was never any question of making anything but
stoneware." and describing his work there.
At the conclusion of this essay, Cardew writes:
"Most of the Abuga stoneware was biscuit-fired before
glazing, but I also developed an interesting
"slip-glaze" containing grass-ash as well as the
wood-ash slag. This fired a clear, transparent, warm
brown on the local clay, an effect which was somewhat
similar to the golden browns of the slipware we used to
make at Winchcombe during the 1920s and 30s. I used it
on the plain dark body, scratching the decoration
through the glaze to the raw clay but owing to the lack
of reliable white slip I was unable to develop its full
potential for sgraffito decoration.
A glaze of the same type, containing grass-ash, local
wood-ash slag and a high proportion of clay, is the
main one used here since my return to Cornwall in 1965.
Over a white slip the golden brown is lighter in tone,
and where the dark body is exposed it tens towards a
black tenmoku. Thus the 'post-West-African' stoneware
made at Wenford Bridge represents, after many years of
searching, a kind of return to the beginnings, and to
the idea, conceived during the 1930s that slipware
techniques, and even the warmth of slipware colours,
could be translated into the new dimension of
stoneware."
Janet Kaiser - snore zzzZZZ snore zzzzZZZZZ...
The Chapel of Art . Capel Celfyddyd
HOME OF THE INTERNATIONAL POTTERS' PATH
Criccieth LL52 0EA, GB-Wales Tel: (01766) 523570
E-mail: postbox@the-coa.org.uk
WEBSITE: http://www.the-coa.org.uk
----- Original Message -----
That's all I have about the story. Perhaps, other
members of the List especially those in England can
shed more light on the
subject.
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