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grid test: unexpected results:chrome yellow

updated thu 1 may 03

 

Stephani Stephenson on mon 28 apr 03


I have started doing some grid tests, finally.
I am running them through both gas firing and electric firing.
The electric kiln I am using is an old Cress which will still stay for
warm five days after
the firing is finished, unless you start propping the lid open a bit
during cool down.
This kiln is INSULATED! I love it, as it allows me to get more complex
glaze surfaces from electric firings.

I recently did a test with flux materials , as well as .75 % copper
and .75 % chrome as colorants.

the most surprising thing happened. In gas firing I got a great range of
greens from limey to grass, etc.
that was expected.
In the electric firing , some of the highly fluxed squares had brilliant
small floating pools of a very pure bright lemony/canary yellow, !
All I can deduce is that the chrome precipitated out during the slow
cool and formed floating pools of chrome yellow!
this was at cone 04. I have seen formulas for the chrome reds and
yellows at much lower temps, such as 018 or so,
or well below cone 010, so this really surprised me!

I think one reason I really like this method is that it is precise, so
it CAN get you from point A to Point B in a well reasoned, direct
manner.
However, you also get to do some fascinating glaze sightseeing along
the way, event if the sights you see (such as this lemony yellow bloom)
are not your goal for the moment.


Stephani Stephenson
steph@alchemiestudio.com
Carlsbad CA

iandol on tue 29 apr 03


Dear Stephani Stephenson,=20

Without knowledge of the ingredients of the glaze you are using it would =
be difficult to make more than a speculative statement about how you got =
from A to B.

Best regards,

Ivor Lewis. Redhill, Australia.