David Hendley on sun 19 jun 05
I am surprised by the replies to Chris Campbell, regarding
stacking bowls for a bisque firing.
Do you folks really have a problem with bowls warping in a
bisque firing? In all my years of making and firing bowls, this
has never been an issue for me.
Any warping that is going to happen takes place either while
the piece is drying, or in the glaze firing, never in the bisque.
I plan what I make with my firings in mind. I think it is not
only wasteful to have big spaces in a bisque kiln, but it makes
for more problems with uneven heating and (especially)
cooling. My SOP for firing 14" bowls in a 28" kiln is to make
some smaller (10-11") bowls to fire in the same load. Two
stacks of 3 of the smaller bowls are loaded in the kiln upside
down, next to the kiln walls, opposite each other, and then
two stacks of the larger bowls are loaded, right side up
in the empty spaces. For the style of bowl I make, this makes
for a perfect fit, with no wasted space. I also put a small,
place-setting-size bowl in with each stack.
I have found that stacks of 3 is my limit, before cracking
problems can happen. As Vince explained, I think the cracking
happens on the cooling, not the heating, because the rims
cool faster than the bases of the bowls.
If I am fining bowls or platters 14" diameter or larger, I always
turn my kiln on high for about 30 minutes, at dull red heat,
when it is cooling, to help raise the temperature of the bowl
rims and slow down the cooling at this critical time.
To me, it is the sign of a real pro when the production is scheduled
with the kiln (both bisque and glaze) in mind. In most kilns it
is important to have pieces of varied height and size to make sure
there is good circulation in the kiln. This doesn't mean you have to
change what you make, just how you schedule what you make.
David Hendley
I don't know nothin' but the blues, cobalt that is.
david@farmpots.com
http://www.farmpots.com
Susan Giddings on mon 20 jun 05
David, Thank you for answering this in the way you did! I, too always have
in mind the constraints of my environment -- the kilns and a public co-op
where many people handle my work. I am one of those in the group who loads
kilns and very often will stack with even cooling in mind. I just always
have in mind how I am to load my pieces. This was reinforced by a workshop I
took several years ago with Jay LaCouture who advertises himself as "a 4th
quarter potter" or as I take it to mean: start with the end in sight. He
takes this to actually refer to how he will glaze the piece. Well, I
certainly do that, too, but I also take it a step or two further and
consider how the piece will be handled (by others), loaded and fired. In
truth, I think he does too, but stacking a kiln was beyond the scope of this
workshop. I think it is very important to consider these factors and once I
am on my own, expect to pay a lot of attention to what I make when. Load
balancing in a kiln is often overlooked.
But to the question asked, I usually stack pieces no more that 3.
Susan
Chris Campbell on mon 20 jun 05
THANKS to all for the great suggestions.
The reason I need 12 large bowls is that I have a large
order for my porcelain work.
The porcelain is once fired at Cone 8 and fires best when
it is 100 percent supported ...thus the bowls !
I now build all of my porcelain inside the forms they will
be fired in ... never have to move them so very little chance
of accidents.
Chris Campbell - in North Carolina - thinking hard about what I wish
someone had told me .... how about what I wish someone had NOT
told me ... all those teachers with rules that could not be broken !!!
Most were pure b.s.
Chris Campbell Pottery LLC
9417 Koupela Drive
Raleigh NC 27615-2233
Fine Colored Porcelain since 1989
1-800-652-1008
Fax : 919-676-2062
website: www.ccpottery.com
wholesale : www.wholesalecrafts.com
Elizabeth Priddy on mon 20 jun 05
This is why I have two electric L&L kilns, one very large and one
18 inch. MY large bowls just fit the J18 and I do not stack them
as I can fit 6 in a firing and at about $8 per firing it is about $1.40
on the cost of the bowl. As I said, I usually fit the interiors of the
pots with small pieces that fill each bowl.
I answered being familiar with Chris's work. I don't know about the bowls,
but for detailed porcelain work, I would not stack them inside each other.
In fact, I don't get why she is bisquing them in the first place. Single
fire after a spraying with clear makes more sense to me.
If she is just making serving bowls with glaze effects, the minor warpage
that will show up in glaze firing, cannot possibly matter except to the
most anal amongst us.
But I don't think she is making simple glazed work.
(Which I like very much, by the way)
E
David Hendley wrote:
I am surprised by the replies to Chris Campbell, regarding
stacking bowls for a bisque firing.
Do you folks really have a problem with bowls warping in a
bisque firing? In all my years of making and firing bowls, this
has never been an issue for me.
Elizabeth Priddy*
252-504-2622
1273 Hwy 101
Beaufort, NC 28516
http://www.elizabethpriddy.com
*If you are an extra-sensitive or easily-offended type:
Remember that what I say is obviously just my opinion based
on my experiences and that I, like most people, don't go around
intending to step on toes and make folks cry. Take it with a
grain of salt and move along, there are others waiting to
give me grief because of their own buttons I inadvertently
pushed...
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