Vince Pitelka on mon 12 mar 12
Liz Gowen is right that terra sig will not retain its full shine above
low-fire temperatures. You have to stop and think about what is happening.
The shine is because the platelets are all compressed flat in a tight layer
covering the surface of the piece, creating a reflective sheen. Any
shrinkage at all will cause that compressed surface to crinkle slightly on =
a
microscopic level, diminishing the shine. For maximum shine on polished
terra sig pots for bonfiring in my Ancient Clay workshops we pre-bisque t=
o
cone-018, and it is doubtful that the bonfiring gets much hotter than that.
In general terms, firing shrinkage is a slow process that happens over the
full curve from low bisque through vitrification as the fluxes and
glass-formers combine to create a glassy phase. The glass seeps out of the
refractory particles into the voids between particles. The particles
shrink, causing firing shrinkage. The minute that starts to happen, the
terra sig shine is diminished. It does happen by degrees, and thus you can
get the best shine at very low-fire temperatures, a little less at low-fire
glaze temperatures, and very little shine once you get into low-midrange or
midrange.
Of course the whole point of ball-milling stains in terra sig is to get
color while minimizing disruption of the shine. If you don't ball mill the
stains, those huge chunks of glass (in comparison to the sub-microscopic
clay platelets) disrupt the shine in a major way. I do worry about
releasing cadmium when ball milling the red zirconium inclusion stains, but
I don't suppose you would have any intention of using a terra-sig coated po=
t
for utilitarian purposes.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Suzanne Storer on mon 12 mar 12
I've had little success after many many hours of effort creating a =3D
colored terra sigillata that remains pink at cone 4 electric. I thought =3D
ball milling mason stain 6009 coral into my white sig would work but the =
=3D
fleshy pink color I get at cone 05 is gone at cone 3-4. Combining my own =
=3D
white sig with commercial underglaze Amaco Velvet 3i6 Light Pink retains =
=3D
it's color up to cone 4 but the surface looses it's sheen. My next step =3D
would be to ball mill this mixture to retain the satiny sheen. However =3D
this is an expensive way to go for application on my large sculptures.
Does anyone have a proven formula for a pink sig that works at cone 3-4? =
=3D
=3D20
Suzanne Storer
Ogden, Utah
Mayssan Farra on mon 12 mar 12
I have not worked with Terra Sig but the regular coral =3D
Hello Suzanne.=3D0A=3D0AI have not worked with Terra Sig but the regular co=
ral =3D
stain did fire off with me when I used it as a stain. Now I use the coral o=
=3D
r lobster "Inclusion stain" much pricier, but stays true to at least ^6. De=
=3D
gussa red stain also works. these are stains encapsulated in Zirconium and =
=3D
very colorful. I don't think you should ball mill them because that might b=
=3D
reak the encapsulation, and I wonder if you really should ball mill the und=
=3D
erglaze as it might have these kinds of stain as the colorant since it did =
=3D
stay true to ^4.=3D0A=3D0AI hope someone with more knowledge of these thing=
s wi=3D
ll step up and answer.=3D0A=3D0AMayssan,=3D0AIn Indian Land enjoying a day =
of war=3D
mth and brightness.=3D0A=3D0A=3DA0=3D0AMayssan Shora Farra=3D0Ahttp://claye=
tte.blogsp=3D
ot.com=3D0A=3D0A=3D0AI've had little success after many many hours of effor=
t crea=3D
ting a colored terra sigillata that remains pink at cone 4 electric. I thou=
=3D
ght ball milling mason stain 6009 coral into my white sig would work but th=
=3D
e fleshy pink color I get at cone 05 is gone at cone 3-4. Combining my own =
=3D
white sig with commercial underglaze Amaco Velvet 3i6 Light Pink retains it=
=3D
's color up to cone 4 but the surface looses it's sheen. My next step would=
=3D
be to ball mill this mixture to retain the satiny sheen. However this is a=
=3D
n expensive way to go for application on my large sculptures.=3D0A>Does any=
on=3D
e have a proven formula for a pink sig that works at cone 3-4?=3DA0 =3D0A>S=
uzan=3D
ne Storer=3D0A>Ogden, Utah=3D0A>=3D0A>=3D0A>
Liz Gowen 1 on mon 12 mar 12
Suzanne, I don't think the sig keeps a sheen that high but I would check
that out with Vince. My thought would be to use a fine slip, mix in the
stain to get the color you want then do a line blend with frit 3134 from sa=
y
7 to 25% and make an engobe with the sheen that will work for you. I would
also try some of the encapsulated stains because they do fire higher but
they are usually a very strong color. I carve porcelain, then paint with
fritted colored slips. I used to just put a light coat of clear over it but
tried several up to cone 6 unglazed and liked the slight melt it got by
itself. Since you are only looking for one color it sounds like this should
be fairly easy to test and find what you like. Some stains are more
refractory than others, and I would also measure the number of teaspoons or
I use a baby spoon with baby jars to mix up the colors so it is more
repeatable. Good luck...Liz Gowen Oh I think I remember you need some
calcium in some of the pink frits that use chrome but shouldn't need it wit=
h
the cadmium.
I've had little success after many many hours of effort creating a colored
terra sigillata that remains pink at cone 4 electric. I thought ball millin=
g
mason stain 6009 coral into my white sig would work but the fleshy pink
color I get at cone 05 is gone at cone 3-4. Combining my own white sig with
commercial underglaze Amaco Velvet 3i6 Light Pink retains it's color up to
cone 4 but the surface looses it's sheen. My next step would be to ball mil=
l
this mixture to retain the satiny sheen. However this is an expensive way t=
o
go for application on my large sculptures.
>Does anyone have a proven formula for a pink sig that works at cone
>3-4? Suzanne Storer Ogden, Utah
>
>
>
Suzanne Storer on tue 13 mar 12
Thank you all for your information. It is helpful. Your suggestion of an =
=3D
engobe, Liz, may be the best way to go. I'll get back to the list later =3D
with the results after further experimentation. Vince, I'm going to =3D
assume no one will be eating off the wall hung figurative high relief =3D
sculpture this is applied to!
Images at the website below.
Suzanne Storer
Ogden, Utah
www.clayartsutah.org/SuzanneStorer/
Brant Palley on tue 13 mar 12
You need to use a body stain, MS6020 pink will stay pink at any temp.=3D20
MS6009 requires calcium for the color to form.
Brant Palley
New Mexico Clay
3300 Girard Blvd. NE
Albuquerque NM 87107
505 881-2350 800 781-2529
Suzanne Storer on wed 11 apr 12
I mentioned I would post the results of my efforts to create a pink sig. =
=3D
With your help I've successfully turning my coral stained white sig pink =
=3D
up to cone 4 by adding calcium as per Brant Palley's and others input. =3D
Thanks again to all who replied. Also the same stain in Vince's hard =3D
white sig with calcium is definitely a different hue - more flesh tone =3D
than pink.
Also I'm wondering if any of you will be going to the 19th San Angelo =3D
National Ceramic Competition in Texas next week?=3D20
I feel fortunate to have one of my figurative sculptures accepted into =3D
the competition especially because Garth Clarke and Mark Del Vecchio are =
=3D
the jurors.
Suzanne Storer
Ogden, Utah
www.SuzanneStorer.com
| |
|
