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red. firing - stacking the pots

updated sat 4 jul 98


John Baymore on fri 3 jul 98

(snip) After three years firing my updraft, downdraft with pretty good
results, I've
started having unevenness in the weirdest places, and not consistently.

The main difference is that I've begun to fire a lot more flat
items--mostly plates. I'm using 2 in. stilts, to leave good clearance,
but am wondering if people have magic stacking techniques for a lot of
flat stuff.


I utilize plate setters for smaller plates. My large setters take a plate
thrown to 12=22 dia. wet. Have smaller ones too. These stack into bungs
and are placed on regular kiln shelves. I might stack them about a max of
3 feet high if they are placed at the top of the stacking. Clearance is
about 1 and three quarters inches in the setters....plenty for a plate.
Pile of plates acts more like a large piece than layer upon layer of kiln

Many suppliers sell plate setters of various sizes.

To generalize (dangerous), if you use shelves to stack plates tend to put
them in the top middle of the stack of shelves, a bit above the top of the
bag walls (if there are any).

In my 16 cu ft kiln, I stack with two rows of 12 x 24's, up four feet.

A 16 cubic foot kiln is pretty small and should fire pretty even with wide
stacking variations. Please e-mail me off list with info on the designer
or the manufacturer. I am interested in the problem.

Thanks John Baymore for your (long) discussion about reduction. I'm one
of those who has always used the damper more than the primary air sources
for reduction. Will try it your way next firing, to see if that helps
even it out, too.

Thanks for the =22thank you=22.

Be careful assuming that the answer for ONE situation is the answer for ALL
situations. Your kiln/combustion system may be very dependent on the
induced flow of secondary air created by the draft of the kiln for much of
your air supply and for adequate mixing and circulation of the mixture in
the kiln. The damper may in fact be a huge determinant of primary air on
YOUR particular kiln.

Not sure all of which postings on this subject you are refering to... but
in many cases the thoughts I give are for a specific case, as close as I
can guess at it from the clues given in the original posting. Follow the
whole thread back. Might not be applicable in other cases. Might be =
There are so many variables to consider in kiln desigh and operation that
there are few =22one size fits all=22 answers. And doing this type of
diagnosis without a lot of data and seeing the installation is difficult.



PS: BTW... a LOT of people from the list have been asking me in private
e-mail if they can reproduce that long posting on reduction and give it out
to their students. Anyone who wants to do that, you may...... just make
sure my name is attached to it and please place a ----- C 1998 All Rights
Reserved ------ line on it somewhere.

John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA