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great high gloss dk. brown glaze and insight???

updated tue 31 dec 96

 

aphesis@interpac.net on sun 1 dec 96

Help! ;)
Oh great glaze gurus, I need your assistance...


We previously used this high gloss, dark brown, glaze in our ceramics
program at Hawaii Community College. A note on the recipe says it's
from Ceramics Monthly '94, p.40, but doesn't give the month. We
discontinued it after last semester. It performs well at cones 8-9
(approx.), but higher and too thick and it pools onto the shelves.
You need to be careful with beginning students who put too much glaze,
so we only stick with foolproof stuff, and this one is very particular
about how thick the glaze is at cone 10. It is a beautiful glaze which
is translucent with incredible depth, appearing like honey.

I downloaded the beta version of Insight and the manual to try and
figure out if it would be of use to me (I figured it'd be way over my
head, and it is, but I want to understand it!!!!). Anyway, I input this
glaze recipe, and have several questions...

The glaze calls for potassium spar, is that the same as potash
feldspar? If not, what?



Honey Gold ^8-10
POTASH FELDSPAR..... 37.50 32.56%
FLINT............... 26.79 23.26%
WHITING............. 15.71 13.64%
BALL CLAY........... 10.71 9.30%
BARIUM CARBONATE.... 5.54 4.81%
GERSTLEY BORATE..... 3.75 3.26%
IRON OXIDE RED...... 9.82 8.53%
MANGANESE DIOXIDE... 3.57 3.10%
BENTOLITE L......... 1.79 1.55%
========
115.18
FORMULA & ANALYSIS
...... 0.10* 4.15% <--what happened here?
CaO... 0.62* 9.19%
MgO... 0.02* 0.21%
K2O... 0.25* 6.21%
Na2O.. 0.01* 0.21%
Fe2O3. 0.23 9.57%
MnO... 0.15 2.80%
TiO2.. 0.01 0.16%
B2O3.. 0.06 1.02%
Al2O3. 0.38 10.22%
SiO2.. 3.52 56.25%


Cost/K 0.52
Si:Al 9.34 <--what does this mean?
SiB:Al 9.49 <--what does this mean?
Expan 4.00 <--what does this mean?


From my understanding of this the ratio of Si:Al looks ok, I thought
lowering the flint might help stop the fussiness at cone 10. Or am I
really confused?

Is this running when thicker just normal. I recall the stuff on
measuring glaze thickness; that would be the ticket?

Foolproof enough for me, but not the prof. He wants to adjust it so that
it *won't* run, or it's not coming back into use here. Any suggestions?

Also, what books, etc. will help me out with understanding this
stuff? ~~
~~~~~~....???
Thanks in advance....... Sam ~(*>*)~
~~\^_/~~
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