Lili Krakowski on fri 2 sep 11
Taking time off from stacking wood, I checked out Digital Fire's site =3D
for Ravenscrag analysis.
And went to the R one that says, Plainsman adds 10% Calcium Carb,
I fed Ravenscrag into Glaze Master (TM) and it figured the glaze thusly:
80 Ravenscraft
20 Frit--Ferro 3134
=3D20
.126 Na2O
.081 K2O
.107 MgO
.686 CaO
1.000 Total
.317 Al2O3
.211 B2O3
.013 Fe2O3
3.121 SiO2
.013 TiO2
9.9 Ratio
65.5 Exp
I am not clear about when the calcium carb is added--so I figured this, =
=3D
adding 10% of=3D20
whiting to the Ravenscraft part of the recipe. And got:
74.1 ravenscraft
18.5 Frit--Ferro 3185
7.4 Whiting
100 Total
Unity Oxide
.123 Na2O
.124 K2O
.099 MgO
.647 CaO
.007 ZnO
1.000 Total
.364 Al2O3
.127 B2O3
.012 Fe2O3
2.882 SiO2
.012 TiO2
7.9 Ratio
70.7 Exp
MgO 1.70
K2O 3
Na2O .50
TiO2 .40
Al2O3 12.70
SiO2 62.10
Fe2O3 .80
The Ravenscrag site suggests 3134 as a flux for R. to make it work =3D
better at c.6
But if my above calculation is on the mark then that 10% calcium carb =3D
lowers the Al2O3 and SiO2 noticeably. But they stay good.
So I do not think that the glaze per se is at fault. Though I would =3D
try Frit 3185 instead of the 3134
74.1 ravenscraft
18.5 Frit--Ferro 3185
7.4 CadyCal 100
.139 Na2O
.14 K2O
.113 MgO
.599 CaO
.008 ZnO
.413 Al2O3
.323 B2O3
.013 Fe2O3
3.265 SiO2
.013 TiO2
7.9 Ratio
67.7 Exp
And would not worry about the Zinc. =3D20
In all this I am omitting the consideration that the glaze might have =3D
defects such as pinholing.=3D20
With all that said. Love hurts, and red wine stains. If you put red =3D
wine in a glass goblet--a shot glass will do--drink the wine and then =3D
let the drop at the bottom dry, you will have a heck of a time getting =3D
it out.
I don't know if it is the wine--the acids in it, the sugars, or some =3D
material--like glycerin--added to the wine. But it just is a nuisance =3D
to get out.
My first suggestion is to make a test as above...My second is to wash =3D
the goblets immediately after use, and try something like some ammonia, =3D
or washing soda, salt, or like that in the washing water...See what =3D
gives.
In breve--said she, being as long-winded as usual--I do not think your =3D
glaze is to blame.
And make some tests letting wine dry on a test tile...
Next week: cocoa cups left to dry out over the weekend!
Lili Krakowski
Be of good courage
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