dianamp@COMCAST.NET on sat 31 dec 11
Tony, for what it's worth:
I once read that the warm color of white slip on historic terra cotta slip =
war
was because of the lead glaze. The lead glaze was often tainted with iron,
probably not purposely, but just from the mining (or the studio environment=
?)
which turned it slightly yellowish and warmed the color of the white slip u=
nderneath.
Some years back, a student of mine wanted that color and tinted our basic
clear low fire glaze with iron to warm it up. Although it was not a lead gl=
aze, it worked.
We have been working (in the university studio) with terra cotta at 04
(and cone 6 reduction) for a long time.
We also use historic low fire techniques with terra cotta, such as cuerda s=
eca, sgraffito,
maiolica, terra sigillata, stains, slip painting, trailing, etc.
Diana Pancioli
Vince Pitelka on sat 31 dec 11
Diana Pancioli wrote:
"I once read that the warm color of white slip on historic terra cotta =3D
slip war was because of the lead glaze. The lead glaze was often tainted =
=3D
with iron, probably not purposely, but just from the mining (or the =3D
studio environment?) which turned it slightly yellowish and warmed the =3D
color of the white slip underneath.
Diana -=3D20
That may well have had something to do with it, but the historic clear =3D
lead glazes would go yellow-buff in reduction firing, and of course most =
=3D
of those ware were fired in wood or coal-fired kilns and were reduced. =3D
Whiteness could be achieved by sealing the ware in saggers, but that was =
=3D
more expensive and time consuming, so thus much of the common ware that =3D
we now treasure was reduction fired. This is why virtually all =3D
Pennsylvania-Dutch ware has that beautiful yellow cast to the white =3D
slip. It's also why the classic Chinese Tang Dynasty lead-glazed =3D
tri-color ware features yellow, green, and brown.
- Vince=3D20
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Steve Mills on sun 1 jan 12
For many years a part of my production was traditional Slipware, fired at f=
i=3D
rst in a gas Kiln, then in electric (I didn't make enough to warrant using =
t=3D
he much bigger gas one).=3D20
In the electric it was a warm cream colour.=3D20
Always the live flame atmosphere of the gas warmed up the Fritted Lead glaz=
e=3D
appreciably.=3D20
Honey glaze only required 5% or less iron oxide else it was too dark.=3D20
I've never managed to replicate that tone and colour in a leadless glaze.=
=3D20=3D
Steve M
Steve Mills
Bath
UK
Sent from my iPod
On 1 Jan 2012, at 00:04, Vince Pitelka wrote:
Diana -=3D20
> That may well have had something to do with it, but the historic clear le=
a=3D
d glazes would go yellow-buff in reduction firing, and of course most of th=
o=3D
se ware were fired in wood or coal-fired kilns and were reduced. Whiteness=
c=3D
ould be achieved by sealing the ware in saggers, but that was more expensiv=
e=3D
and time consuming, so thus much of the common ware that we now treasure w=
a=3D
s reduction fired. This is why virtually all Pennsylvania-Dutch ware has th=
a=3D
t beautiful yellow cast to the white slip. It's also why the classic Chine=
s=3D
e Tang Dynasty lead-glazed tri-color ware features yellow, green, and brown=
.=3D
> - Vince=3D20
>=3D20
> Vince Pitelka
> Appalachian Center for Craft
> Tennessee Tech University
> vpitelka@dtccom.net
> http://iweb.tntech.edu/wpitelka/
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