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^6 glazes and slow cooling-a bit long

updated fri 2 dec 05


Gene & Dolita Dohrman on thu 1 dec 05

A number of people emailed me off-list expressing an interest in the firing
cycle I mentioned. It all began with the new ^6 Frost post. I have never
used Frost. Most glazes in MC6Gs and Bailey's book will look fine on
porcelain but be careful with the runny glazes...they will run even more on
porcelain. There were some awesome ^6 glazes in CM, the Sept. 05 issue.
Ketchup Red on Highwater's Earthen Red is simply beautiful. Tested them all
except the clear and that is next on my list. You want a stunning glossy
green, try Costello Carb-gorgeous on B-mix.
Only one thing I must warn about before using a slow cool cycle, make sure
your clay does not have a high amount of crystobolite in it. It does not
like a slow cool. I just used a bag of Standard #112 which I understand
contains a whole bunch of crystobolite. I used Spearmint on quite a few
All the pieces with Standard #112 bubbled. All the others were perfect.
I don't know a lot about specific clay composition so I would check with the
people who make Frost and ask them.
This firing schedule develops beautiful glossies and perfect matts. Now I
am not saying my pots are perfect, wish the kiln could fix some of my forms,
but the glazes come out nicely. Licorice and Liner White in particular like
this schedule. No pits, very smooth surface. Licorice likes to be thick.
Ron and John have been instrumental in determining my firing schedule.
Everytime they tweak, I tweak. I understand that one of them now soaks at
1400 but I am not going to fix what is not broken for me.

Segment 1 60/hr to 200 Hold 3 hours (On my kiln this takes about 6 1/2
hours) (I load right after I glaze so I need to be sure everything is dry)
Segment 2 350/hr to 2000 (This takes another 5 1/2 hours)
Segment 3 60/hr to 2155 Hold 20 minutes (If you start your kiln at about
9:00 in the evening, you can start watching it at 8:00 in the morning. Your
peak temp may differ from mine. I have ceramic covers on the thermocouples
so the temp. is offset by about 30 degrees. Watch the cones. I want it to
go into a soak right about when the ^6 is between 10 & 11 o'clock, mine face
left. The 6 should be touching at the end of the soak, and the 7 should be
soft, just a bit of a curve. That is how I like it, you may decide
Segment 4 150/hr to 1800 Hold 20 minutes
Segment 5 100/hr to 1400
The whole cycle takes about 19 1/2 hours and costs me about $5.00. Pretty
good if you ask me! I have an L&L Easy Fire it...3" brick and a
vent. Had a huge pot explode in my kiln (was not mine) and the spout wedged
in between the channels for the elements. Not a scratch!
With these programmable kilns I guess it is easy to set and walk away. I
need to have some control. If it is a light load, I may have to reprogram
the kiln to lower the peak, if it is really full, I just extend the hold.
The kiln will pick up where it left off.
Spearmint from MC6Gs loves this schedule. It looks good on many different
clays. However, it does not look good on stoneware with a high iron
content. I just tried Trina Buff and when it bisqued pink, I knew I was in
trouble with some of my glazes, especially the greens.
I hope you all can make some sense of this post. In review, I seem to be
all over the place. Testing glazes is very exciting. Tom Buck started me
on the path, and I have just kept on going with the help of Sandy Miller and
Alisa Clausen. Wish Ababi was still with us...what fun we could have!
Happy testing!
Dolita - in Kentucky where the wind is blowing, the sky is gray, but we had
big, fluffy snowflakes today!

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