Alisa Liskin Clausen on sat 30 dec 06
that crazes.
Dear Clayart,
Over time I have noticed a pattern when I test clear bases with coloring
oxides.
Base glazes that craze on my clay body, can appear with no crazing when
coloring oxides are added.
In most cases, percents of 5-10 RIO or 1-2 Cobalt will show un crazed. I
have not studied these surfaces under
a microscope, but they are clearly improved surfaces when looking at them in
sunlight. An example of this is the last colorant tests I made,
using Brian Gartside's Volume Clear Glaze. The clear was badly crazed, but
all the tiles, colored with RIO and Cobalt, were not crazed.
However, since the base was crazed, I feel nervous about the seemingly un
crazed tiles. I mean, maybe they are crazed, but I do not see it.
Or, like shivering can much later, perhaps crazing can also happen much
later.
I have used this base now in a bigger batch with 10 RIO, and the pots are
not crazed, as I can see. In fact, the glaze is looks like a lush Tenmoku
at Cone 6.
Contrary to this improvement, I have seen Copper Oxide as a colorant, make
an un crazed clear glaze,
craze.
I would like to study this closer. Is there any documentation on the above?
Suggestions for glaze testing to
further investigate this? Do coloring oxides have an effect on expansion of
a glaze? Maybe a big yes, and this is an
area I in the dark about, or, it could be something interesting to study.
After the weekend, I am starting up again and would like to look into this
relationship, if there is one.
These evenings I have reread all of the articles I thought where interesting
in my year of Clay Times and Pottery Illustrated.
I think the columns in Clay Times have excellent information that one can
benefit from reading a few times.
Best regards from Alisa in Denmark
Cloudy, stormy New Year's Eve predicted,
so not so good for seeing fireworks. Tradition calls
for the Queen's New Year's address, a dinner of codfish and mustard sauce,
and literally jumping into the New Year, from little stools or chairs,
depending on one's
bravery.
Alisa Liskin Clausen on sat 30 dec 06
that crazes.
Dear Clayart,
Over time I have noticed a pattern when I test clear bases with coloring
oxides.
Base glazes that craze on my clay body, can appear with no crazing when
coloring oxides are added.
In most cases, percents of 5-10 RIO or 1-2 Cobalt will show un crazed. I
have not studied these surfaces under a microscope, but they are clearly
improved surfaces when looking at them in sunlight. An example of this is
the last colorant tests I made,
using Brian Gartside=92s Volume Clear Glaze. The clear was badly crazed,
but all the tiles, colored with RIO and Cobalt, were not crazed.
However, since the base was crazed, I feel nervous about the seemingly un
crazed tiles. I mean, maybe they are crazed, but I do not see it.
Or, like shivering can happen much later, perhaps crazing can also happen
much later.
I have used this base now in a bigger batch with 10 RIO, and the pots are
not crazed, as I can see. In fact, the glaze is looks like a lush Tenmoku
at Cone 6.
Contrary to this improvement, I have seen the addition of Copper Oxide as
a colorant, make an un crazed clear glaze,craze.
I would like to study this closer. Is there any documentation on the
above? Suggestions for glaze testing to further investigate this? Do
coloring oxides have an effect on expansion of a glaze? Maybe a big yes,
and this is an area I in the dark about, or, it could be something
interesting to study.
After the weekend, I am starting up again and would like to look into this
relationship, if there is one.
These evenings I have reread all of the articles I thought where
interesting in my year of Clay Times and Pottery Illustrated.
I think the columns in Clay Times have excellent information that one can
benefit from reading a few times.
Best regards from Alisa in Denmark
Cloudy, stormy New Year=92s Eve predicted,
so not so good for seeing fireworks. Tradition calls
for the Queen=92s New Year=92s address, a dinner of codfish and mustard sauc=
e,
and literally jumping into the New Year, from little stools or chairs,
depending on one=92s bravery.
Ivor and Olive Lewis on sun 31 dec 06
Dear Alisa,
This seem to be one of those problems which is best solved by using a =
Glaze Calculation Program.
Provided it is possible to find values of Ceof of Expansion of colouring =
oxides and insert them into the algorithm you should get an answer to =
the questions you ask.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
May Luk on wed 3 jan 07
that crazes.
Hello Alisa;
This is a good time to review David Hewitt’s excellent
writing again on crazing and the pesky COE values by
different ceramists. It is also time to take out the
book Out of the Earth, Into the Fire by Mimi Obstler.
John H made some good suggestions, but I think it is a
bit ambitious. Although I am sure you can handle it.
His method involve glazes in various PH and Si:Al
ratio. I would be nervous if I have to vary too much
of those too soon as we know PH and Si:Al (Are they
the same thing?) affect how colouring oxides behave.
Perhaps that is exactly the point. I found small steps
and simple objective set up a comfortable base camp
for a long glaze trail. How about just change one
variable at a time? Like varying the percentage of the
colouring oxide and get yourself some serious
equipments that go beyond 20/20 to see the effect of
the oxides on stopping crazing in a crazed base glaze?
The result might gives suggestions to further testing
ideas.
I’ll be doing massive glaze testing in the USA in the
coming months. Let’s keep chatting and exchange ideas.
A friendly reminder: Please don't forget to quote the
ceramist on COE values.
Be seeing you!
May
Kings County
P.S. I just got the book On Food and Cooking by Harold
McGee at a used book store. I am fascinated by photos
of things in a microscopic level. Maybe it is the
effect of the [6.8?] San Francisco earthquake in 1986,
I don’t mind feeling small.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
[...]
I would like to study this closer. Is there any
documentation on the
above? Suggestions for glaze testing to further
investigate this? Do
coloring oxides have an effect on expansion of a
glaze? Maybe a big yes,
and this is an area I in the dark about, or, it could
be something
interesting to study.
After the weekend, I am starting up again and would
like to look into this
relationship, if there is one.
These evenings I have reread all of the articles I
thought where
interesting in my year of Clay Times and Pottery
Illustrated.
I think the columns in Clay Times have excellent
information that one can
benefit from reading a few times.
Best regards from Alisa in Denmark
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