Susan Ross on thu 16 jul 98
Hi All --
We've recently developed a problem with stress type cracks (sharp rather than
meandering) on pots fired to ^5 in our Skutt KM1027. Most appear on ^5 B-Mix
pieces glazed with MS Sunflower and Colonial White glazes. Also a ^10 Black
Mountain piece or two. Handbuilt and thrown pieces.
I fire ^5 SLO no HOLD. Peepholes are all plugged and tight throughout firings.
Vent runs entire firing and cooling.
I was wondering if the vent is pulling air straight down the sides of the
kiln, hitting edges of pots hanging over shelves and causing cracking upon
cooling.
The three holes drilled on the lid of this kiln are located within 4" of the
outside edge of the lid as opposed to the very center of the lid. Could this
be the culprit?
Any other suggestions?
TIA
Su
Piedmont Clay Studio
hot ... hoT ... hOT ... HOT today!
Clyde Tullis on fri 17 jul 98
How fast does it cool? F/hr.?
I would worry about any draft passing through the kiln at that time.
Clyde Tullis
c/o Raven Hill, Inc and MUDLARK POTTERY
0111 County Road 45
Howard, CO 81233
719-942-4772
FAX 719-942-3211
mudlark@ris.net
Jonathan Kirkendall on fri 17 jul 98
Hi Susan,
I used to turn off my envirovent as soon as my cone began to move, back
before I really understood soaking. But now I keep the vent going right
through the next day when I unload and have not had any problems, either
with my glazes or with cracks like you describe. I fire to cone 6 (with
a cone 10 in the sitter to make sure that it doesn't switch off before
the soak). When the ^6 is down, I turn the switches to medium for an
hour, then to low for an hour, then off. Last night I was tired and when
the cone 6 went down, I turned the switches to low, went to bed, got up
at some point several hours later and turned it off, with the vent still
going. Everything looks fine.
Jonathan in DC, where it is hot and muggy, a fine July day.
| |
|
