Ababi on sat 22 mar 03
Once upon a time an American potter, I would say, a well known American po=
tter
wrote an Article about Oilspot glazing.
You Don't have to teach me John!
There are always oil spots in my coffee mug that has been used as a soup m=
ug
before!
I do not wash - I am afraid my glaze will peel off!
This glaze I found in the Ceramic web database of ClayArt.
(Which is another choice to thank Richard Burkett for this site):
http://art.sdsu.edu/ceramicsweb/
OIL SPOTS ^6-^10
I copy from the site:
Glaze Name: Oil Spot
cone: 5 - 6 - 7 - 8 - 9
color: black
surface:glossy
firing: oxidation
date: 4/3/98
recipe:
4.91 EPK
78.86 Feldspar
5.48 Whiting
10.75 Gerstley Borate
100.00 % Total for base glaze
Also add:
4.13 Copper Carbonate
4.13 Manganese dioxide
2.07 Cobalt oxide
comments:
From the ClayArt Glaze Recipe Database at SDSU.
If you test this glaze and find it useful
please consider resubmitting it to the GlazeBase database.
estimated thermal expansion: 84.30x10-7/=B0C
Unity Formula for Oil Spot:
0.357 K2O 0.627 Al2O3 3.922 SiO2
0.193 Na2O 0.184 B2O3 6.3:1 Si:Al Ratio
0.410 CaO
0.041 MgO
Percentage Analysis for Oil Spot:
61.60 % SiO2
16.71 % Al2O3
3.35 % B2O3
8.78 % K2O
3.14 % Na2O
6.01 % CaO
0.44 % MgO
Possible Health Hazards: Manganese Dioxide: TOXIC-avoid inhalation-wear a =
NIOSH
approved dust mask when handling dry material
Comments: Nice shiny black, works nicely with other glazes to get interest=
effects.
Try WG white with this one. I have spent about a year reading all of the g=
ood things
you all have had to share and thought it is my turn to do some of the givi=
ng. Here are
some formulas that I have gathered from the studio. I don't know who the o=
riginal
creators of these are. Hope you all enjoy them: sue hintz >
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Please note 0.627 Al2O3 This is not ^6!
So what happened:
I got shiny glossy not runny black. I made it tried to substitute the GB f=
ailed and kept
the recipe in a corner of my brain.
To Matrix, again I changed the name according to the results:
In this version I changed the colorants and got it a blackish green:
GLOSSY DARK BLUE
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Cone 6 1222 deg.C. -
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Custer feldspar 78.90
Calcium Carbonate 5.50
Gerstley Borate 10.70
EPK Kaolin 4.90
Copper carbonate 5.00
Manganese Dioxide 1.00
Cobalt Oxide 2.00
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Seger Weight%
KNO 0.532 11.55%
CaO 0.424 6.22%
MgO 0.043 0.46%
Al2O3 0.625 16.63%
B2O3 0.157 2.85%
SiO2 3.967 62.28%
TiO2 0.001 0.02%
K2O 0.347 8.55%
Na2O 0.185 3.00%
Al:Si 6.35
Expan. 8.21
ST 347.25
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
One of the things that convinced me to buy Matrix was a sentence was writt=
en by
Lawrence Ewing, when I asked about support: "We are only an e mail away". =
He
wrote.
Trying to understand the recipe led to some questions:
The copper cobalt and manganese are flux
Please see the formula when I consider the colorant-flux- oxides in the ca=
lculation:
GLOSSY DARK BLUE
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Cone 6 1222 deg.C. -
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Seger Weight%
KNO 0.461 11.20%
CaO 0.367 6.03%
MgO 0.037 0.44%
Al2O3 0.540 16.13%
B2O3 0.136 2.76%
SiO2 3.432 60.41%
TiO2 0.001 0.02%
K2O 0.301 8.29%
Na2O 0.160 2.91%
CoO 0.0942 2.07%
MnO 0.0406 0.84%
Al:Si 6.35
Expan. 8.01
ST 347.25
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
I don't know how Lawrence calculates the relations of the materials, flux =
I know but he
considers the whole thing you can see that adding so much cobalt and coppe=
r
reducing - even theoretical the amounts of the alumina and silica
http://tinyclick.com/?R17HO6
Or in
http://members4.clubphoto.com/ababi306910/981929/
What can we do with this glaze?
I would not eat from it but it can be apply on the foothill of tall crysta=
l ware to avoid the
running of the crystal glaze to the bottom and ruining the ware. In my cr=
ystal glazes
page you can see such wares with a different "foothill glaze"
The Oilspot glaze looks like the black glaze in the page
But the black glaze on that page is a different one
I shall write about the other glaze in another letter.
Good night sleep well
Ababi
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