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chrome-tin red glaze base from scratch

updated fri 9 apr 99


Fabienne Cassman on thu 1 apr 99


I finally dug up my Hyatt napkin from NCECA where I annoted the following:

How to make a Chrome-Tin Glaze:

-Must have 3 times as much CaO than B2O3 - However, does it matter if it's
percentage (FM033199a) or is it unity (FM033199b)? Then again, what if the
B2O3 is not in unity? I would think that percentage is what I am shooting
for. Can anyone confirm?

-No zinc and low MgO

The COE is in the ballpark. I am using Green=26Cooper's limits and tried to
keep it within as best I could. I don't expect it to line functional ware
anyway, but just curious to see if it can be achieve while still reasonably

Assuming all is well with either one recipe. According to Harmer=26Hamer
chromium should be between 0.5=25 and 0.1=25, below that we are in the =
range=22 when there is less than 5=25 tin. I can see doing a line blend =
one base containing the chromium (0.5=25) and the other the tin, but 5=25 =
hardly seems to be the number to start with unless I am shooting for a
pink. How much tin can this type of glaze take? Any suggestion as of
where to start testing to locate the magic combination?

Also, I remember seeing two type of chromium colorant=3B one was green and
the other one black. Which one should be used?

I used the following ingredients because they worked well for my clear and
they are readily available.

Two Recipes: FM033199a =26 FM033199b - c6ox Red Glaze Bases
SILICA.............. 22.50 22.50=25 21.00 21.00=25
FRIT 3134........... 13.75 13.75=25 16.75 16.75=25
WOLLASTONITE........ 15.75 15.75=25 14.50 14.50=25
CUSTER SPAR......... 35.00 35.00=25 33.50 33.50=25
EPK KAOLIN.......... 13.00 13.00=25 14.25 14.25=25
=3D=3D=3D=3D=3D=3D=3D=3D =
100.00 100.00

CaO 0.57=2A 9.77=25 0.55=2A 9.86=25
MnO2 0.00 0.00=25 0.00 0.00=25
MgO 0.02=2A 0.26=25 0.02=2A 0.24=25
K2O 0.13=2A 3.67=25 0.12=2A 3.52=25
Na2O 0.14=2A 2.58=25 0.14=2A 2.85=25
Fe2O3 0.00 0.16=25 0.00 0.17=25
TiO2 0.00 0.04=25 0.00 0.04=25
B2O3 0.15=2A 3.25=25 0.18=2A 3.97=25
Al2O3 0.36 11.45=25 0.35 11.66=25
SiO2 3.73 68.80=25 3.50 67.67=25
P2O5 0.00 0.02=25 0.00 0.02=25

COST/KG 1.42 1.50
Si:Al 10.22 9.87
SiB:Al 10.63 10.37
EXPAN442.17 444.38

TIA :)

Yes, I have learned from my mistakes...
I can reproduce them exactly.

Fabienne Cassman on thu 8 apr 99

To follow up on my pop quiz post for making Chrome-Tin glazes, the base was
deemed to be fine for a red on a cone 6 porcelain body. Tin should be 5=25
according to Hamer and Chrome oxide can be as little as 0.015. Whether the
Chrome should be green or otherwise is unclear still=3B so I will probably
try both the one that are available to me. If someone decides to try the
recipe, too, and beats me to the finish line, let me know how it went. Thx =


Yes, I have learned from my mistakes...
I can reproduce them exactly.