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Re: black on black pottery

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From: Marvin Bartel (marvinpb_at_TeacherArtExchange)
Date: Thu Oct 31 2002 - 06:09:14 PST


Black Native American and African pottery is generally the result of
smothering the red hot pottery in smoke (carbon) at the end of the outdoor
pit firing. It is achieved by closing off all air to the inside of the wood
or dung fired kiln at the end of the firing. A similar black result is
achieved by contemporary raku techniques developed by Paul Soldner and
others in the 1960's. In western raku the red hot pot is quickly placed in
an air-tight metal smoking container containing paper, dry leaves, saw
dust, etc. In a tight metal container with the sawdust added on top of
the hot pot, the smoke can blacken the whole pot if it is unglazed. Pots
prefired to bisque at about 010. Greenware will break unless heated very
very slowly - which is possible.

Because of the dense smoke, raku is not practical unless you have the kiln
outside or an exit door next to the kiln where the hot pot, held with
tongs, can quickly be moved to the smoking container outside. Even
outdoors this could be very hazardous unless students are responsible and
well supervised with water handy to put out clothing fires. When a smoking
container with red hot pottery is opened it can flame up very quickly and
dangerously. I do know a number of high school ceramics teachers in our
area who do this with good results (and without accidents to people). In
many years of doing this with students, the worst things I have seen are
some burned eye lashes or somebody stepping on a hot shard and damaging a
shoe. I require real shoes - no sandals or barefoot potters around the
raku area. Long hair should be tied back.

Of course there are lots of pottery accidents, such as cracks and breaks.
Keep the Elmer's glue handy. Some see raku firing as a party to encourage
happy accidents to happen.

Burnished clay shows up best when the firing is around cone 010. High
fired stoneware and porcelain does not show it much. Typically, polished
pottery is decorated by painting slip over part of the burnished surface to
cover up the polish in areas that fire to a dull contrasting black texture
- hence the term "black on black". Other decorating methods include
incising and carving the clay. Non-toxic low fire glazes could be used as
liner to help make the ware more washable, but most people do not think of
this as functional pottery. For vases, I line ovenheated pots with parafin
wax by shushing it in and pouring it out. These do not wet the table when
used for flower vases.

The traditional Japanese Raku is a pottery tea bowl tradition resticted to
the Raku family. It is not often black, but it did inspire some of the
first western potters to experiment. This evolved to what we now think of
as raku.

Marvin Bartel
Goshen College
1700 South Main Street
Goshen IN 46526
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studio phone 574-533-0171
fax 574-535-7660
marvinpb@goshen.edu
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http://www.goshen.edu/~marvinpb/throw/cover39.html
http://www.goshen.edu/art/DeptPgs/castable.html
http://www.bartelart.com
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At 05:20 AM 10/31/02 -0500, you wrote:
>I know that it is possible to achieve a "black on black" pottery result with
>a pit firing, but what about in an electric kiln? Is there any way to pull
>this off? I don't think so, but I thought I would put the question out to
>our ceramic gurus. Also, a while back, someone gave directions for
>burnsihing leather hard/bone dry pots. I did that, but have not fired it
>yet. Do I need to fire it at a certain cone to retain the burnished
>surface?
>Thanks,
>Marian
>
>
>---
>

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