Llewellyn Kouba on wed 1 mar 00
Readers:
I have a commission for a porcelain tea set and wonder what to do? The
client wants all black and it is hard for me to set my personal prefrences
aside and - just do black. I was thinking of doing Tom Colemans ' FILLY
BLACK' . I have the tea set made and don't want to take a lot of time
testing for a glaze I may never do again. I would think some other color
would add interest to black but again this client wants an all black
porcelain tea set. Any suggestions out there ?
cone 9 black tea for two
Llewellyn Kouba
ABBEY POTTERY
http://www.assumptionabbey.com/Pottery
Cantello Studios on thu 2 mar 00
This is a very nice black you Seattle slip In place of albany or other dark
clay slip it dose have alot of oxides
but I love it . Its very stable stays where you put it, on the pot not the
shelf. Chris
++++++++++++++++++++++++
+++ Mirror Black +++
++++++++++++++++++++++++
Range: 10/11
Firing type: Ox/Reduction
Glaze type: High-fire
Color: Black
Surface: Gloss
Transparency: Semi-opaque
Visual texture: Speckled
Crystals: Small
Bubbles: None
Flow: None
Flaws: None
Durability: Good
Testing: 1978/Jacks class
Date: 02/04/99
G-200 49.6 49.6%
Whiting 15.35 15.4%
Albany Slip 9.45 9.4% Hazard! (Not available)
Barium carbonate 2.36 2.4% Hazard!
Flint 23.24 23.2% Hazard!
-------- ------
100 100 %
Manganese carb 2.36 2.4% Hazard!
Cobalt carbonate 3.54 3.5% Hazard!
Chromium oxide 1.18 1.2% Hazard!
Red iron oxide 4.72 4.7%
Bentonite 3.54 3.5% Hazard!
Notes:
You can over spray this glaze and get silver and with a lite over spray
you can get a oil spot look.I have even seeded some Tio2 and Iron in to
the glaze.Good Luck. This glaze came from Chico State glaze cal. class of
1979 via.Don via. nancy via. Chris keep it clouse to your Hart :)
Material Hazards:
Albany Slip - dust hazard
Barium carbonate - poisonous - may leach out of glazes
Flint - dust hazard
Manganese carbonate - irritant
Cobalt carbonate - irritant
Green chrome oxide - very poisonous - irritant
Bentonite - dust hazard
Cost: $ 3.06 per kg glaze
$ 0.31 per 100 g batch
===========================
Chemical Analysis
===========================
This glaze contains unexpected oxides: SiO2
Na2O 0.08 Al2O3 0.35 TiO2 0.00
K2O 0.18 Cr2O3 0.02 Fe2O3 0.10
MgO 0.03
CaO 0.53
MnO 0.06
CoO 0.09
BaO 0.04
Alumina:Silica ratio is 1.00 : 9.19
Neutral:Acid ratio is 1.00 : 0.28
Alkali:Neutral:Acid ratio is 1.00 : 0.37 : 0.10
Na2O 1.6% Al2O3 11.2% TiO2 0.1%
K2O 5.2% Cr2O3 1.1% Fe2O3 5.1%
MgO 0.3%
CaO 9.3%
MnO 1.4%
CoO 2.1%
BaO 1.8%
This glaze also contains:
SiO2 60.8%
Loss On Ignition: 9.2%
Expansion coefficient: 80.9 x 10e-7 per degree C
Viscosity index: -2.4
Surface Tension index: 2.2
Onset of oxide volatization:
H2O 100 C (complete loss)
CO,CO2 700 C (c/018) (complete loss)
Cr2O3 1050 C (c/04) (partial loss)
Na2O 1100 C (c/02) (partial loss)
CoO 1100 C (c/02) (slight loss)
BaO 1200 C (c/6) (slight loss)
MnO 1200 C (c/6) (slight loss)
K2O 1200 C (c/6) (slight loss)
Materials in glaze:
G-200 Feldspar provides SiO2, Al2O3, K2O, Na2O, and CaO.
Whiting provides CaO.
Albany Slip provides SiO2, Al2O3, Fe2O3, CaO, and other oxides.
Barium carbonate provides BaO.
Flint provides SiO2.
Manganese carbonate provides MnO. Used as a colorant.
Cobalt carbonate provides CoO. Used as a colorant, acts as flux.
Green chrome oxide provides Cr2O3. Used as a colorant.
Red iron oxide provides Fe2O3. Used as a colorant.
Bentonite provides several oxides. Ususally used as a suspending agent.
Oxides in glaze:
Na2O is a strong alkaline flux.
K2O is a strong alkaline flux.
MgO is a high-temperature flux.
CaO is a high-temperature flux.
MnO is a colorant (black, brown, and purple).
CoO is a colorant (blues and purples).
BaO is a flux over a wide temperature range.
Al2O3 increases viscosity, prevents crystallization, and adds durability.
Cr2O3 is a colorant (greens, pinks, orange, and red).
TiO2 adds opacity and encourages crystal formation.
Fe2O3 is a colorant (tan, yellow, brown, red, and black).
In reduction, Fe2O3 -> FeO, which is a flux and colorant (brown, black).
SiO2 is the primary glass-former in glazes.
=======================
Cost Summary
=======================
G-200 49.6% $ 0.27 per kg glaze
Whiting 15.4% $ 0.08
Albany Slip 9.4%
Barium carbonate 2.4% $ 0.07
Flint 23.2% $ 0.13
------ -------
100 % $ 0.55 per kg glaze
Manganese carb 2.4% $ 0.35 per kg glaze
Cobalt carbonate 3.5% $ 1.72
Chromium oxide 1.2% $ 0.25
Red iron oxide 4.7% $ 0.16
Bentonite 3.5% $ 0.03
-------
$ 2.51 per kg glaze
Total cost: $ 3.06 per kg glaze
$ 0.31 per 100 g batch
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.UKY.EDU]On Behalf
Of Llewellyn Kouba
Sent: Wednesday, March 01, 2000 9:47 AM
To: CLAYART@LSV.UKY.EDU
Subject: Looking for a good black glaze cone 9
----------------------------Original message----------------------------
Readers:
I have a commission for a porcelain tea set and wonder what to do? The
client wants all black and it is hard for me to set my personal prefrences
aside and - just do black. I was thinking of doing Tom Colemans ' FILLY
BLACK' . I have the tea set made and don't want to take a lot of time
testing for a glaze I may never do again. I would think some other color
would add interest to black but again this client wants an all black
porcelain tea set. Any suggestions out there ?
cone 9 black tea for two
Llewellyn Kouba
ABBEY POTTERY
http://www.assumptionabbey.com/Pottery
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