Alisa Liskin Clausen on sun 6 feb 05
>Alisa,
>
>I was very curious about your firing schedule. I fire to cone six and
hold for one hour at the very end of the firing. Once I hold for one hour
at cone six, I fire down slowly from there.
>
>What is your thought about firing down to 1475 and holding at the lower
temp for one hour?
>
>I was always hold at the top to burn out any unwanted materials. I have
never met any one that holds at a lower temp.
>
>I would be interested in trying it your way, but am curious to find out
your reasoning behind it.
>
>Thank you!
>Michael Baxley
>Kansas City
Dear Michael,
This is a tricky question, because it depends on several things about your
firing. What types of glazes you are firing and kiln performs.
As you know, the hold at the top is to give the glaze time to smooth and
heal over any blisters or bubbles that may have occured. I admit a 5 minute
hold is short, usually 10-20 minutes is average. Could be, I will increase
it to 10 minutes, but my present cycle works for my glazes and kilns. One
hour at the top may be, in general, a long hold. Secondly, the controlled
firing on the way down, is to get crystals to form in mat glazes
or "shells" to form on gloss glazes. Sometimes a mat glaze can have a
glassy shell. I fired this schedule because I wanted a hold on the way
down, but what not sure where. Another Clayarter, Cindy Strnad (?
spelling, where are you??? used to be in SD, got married and hopefully
enjoying a wonderful married life) told me to try holding at 800c. I tried
it in the old kiln, that was 30 years old , and I did not see a noticable
difference in the glazes. This is also probably the lowest temperature from
where you would let your kiln cool naturally and see any improvement in the
glazes.
Alhtough I do not know how to fire crystal glazes, but I am under the
impression that they need holds at lower temperatures than at the top, and
then raise the temp. again, and back down and hold. So, there are people
who hold below the top temp. I am sure.
Then when the book MC6G emphasised how important is is to slow cool, I
tried another ramp closer to the one in the book. I had a brand new kiln,
which is smaller than my old kiln, but same glazes. I tried a few
variations of it and each time, I was getting too much heat work, and my
glazes looked streaky and overfired. Some of the gloss glazes had holes of
bare clay where the glaze ran off the wall of the pot, but not below the
bottom margin of the glaze. I thought because the kiln had new elements,
smaller, maybe this too slow on the way down.
I went back to firing with the natural cool down to 800c and off and the
glazes all look like I think they should.
I would say if your ramps are producing the surfaces you think are right
for your glazes, I would not necessarily alter them. As long as you have a
soak at the top and the glazes get time to develop the surfaces they are
supposed to have on the way down, that works for you. I do it this way
merely by a suggestion from a Clayarter and then seeing that it worked
better this way for my particular kiln and glazes, then other ramps I have
tried.
That is how I came to using the ramp I have. But on second thoughts now
because of this question, I think I will slightly up the hold at the top
before letting it cool down to 800c. It is mostly important to adjust your
firing, or not, to get the glaze results you want. MC6G has a lot of good
suggestions for ramps.
regards from Alisa in Denmark
>
baxleypottery@netzero.net on mon 7 feb 05
Alisa,
Thank you for taking the time to share that information. I will most likely shorten my top hold a tad, but am still interested in trying your ramp just to see what happens. I use a lot of wood ash glazes and matte crystal glazes, so that just might be in my favor!
Thanks again!
Michael Baxley
Kansas City USA
www.BaxleyPottery.com
P.S. I am really interested in the mouse brown glaze and am going to test it out!
Alisa Liskin Clausen on tue 8 feb 05
>P.S. I am really interested in the mouse brown glaze and am going to test
it out!
>
Let us hear your results!
regards from Alisa
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