John Baymore on wed 25 sep 02
julie,
I have heard that the junk given off in burning the paper
(either in paper clay or sculptures with paper filling) can
shorten the life of the coils. That makes sense -- I'm sure
it settles on and eventually has some effect on the coils.
I haven't had any problems - except for a headache here and
there.
Any time you fire combustible materials in an electric kiln you have the
POTENTIAL to create an oxygen starved atmosphere......IF there is
insufficient oxygen flowing through the kiln (as from a local pickup kiln=
vent) to completely burn the material. The more of that combustible
material....... ie. paper in paperclay.......... the more volume of air y=
ou
need to flow through the kiln in a unit of time. =
Those oxygen starved reducing conditions take some life off the elements =
by
removing some of the very fine layer of protective oxide coating that for=
ms
on the elements under oxidizing conditions. When you refire under
oxidizing conditions.... the oxide coating re-forms..... taking a little
more metal away from the element..... and changing it's electrical
resistance ever so slightly. Over time.... the decrease of the thickness=
of the element and it's affiliated resistance change....add up. And the
kiln takes longer and longer to get to temperature bue to decreased heat
output from the elements.
The life you take off the elements by firing any kind of reducing
atmosphere in an electric kiln is just a "cost of doing buisiness" . =
If
you want to reduce in an electric kiln...... you'll replace elements a
little more often than those who don't. Simple .
Your "headache here and there" might well be from carbon monoxide leaking=
into the room air from the kiln. If that is a regular occurance.... you
might want to look at the kiln ventilation system. The next time you are=
firing a load of paperclay....get a Nighthawk carbon monoxide detector wi=
th
a digital ppm display and place it on the wall at head height somewhere
near the kiln. See what the display has to say.
Best,
..............................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752 (s)
800-900-1110 (s)
JohnBaymore.com
JBaymore@compuserve.com
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