DJ Brewer on fri 18 feb 11
Howdy folks
Not sure if anyone else had noticed this with their kiln -- but when I
set my kiln to candle at 195 to dry out any last vestige of water, I was
shocked to see that the kiln had crept up to 214 -- which, of course,
would have had adverse affects on anything with moisture left in it.
Since that time, I set my kiln to candle at 170, to err on the side of
caution rather than on the side of explosion!
Maybe my kiln is quirky -- but it fires fine, and so I'm taking this
route to be sure I don't blow a pot because I set the candling temp too
high.
(PS I'm somewhat of a noob so if candle is the wrong term, please
forgive and correct me!)
thanks
DJ
William & Susan Schran User on fri 18 feb 11
On 2/18/11 4:25 PM, "DJ Brewer" wrote:
> Not sure if anyone else had noticed this with their kiln -- but when I
> set my kiln to candle at 195 to dry out any last vestige of water, I was
> shocked to see that the kiln had crept up to 214 -- which, of course,
> would have had adverse affects on anything with moisture left in it.
> Since that time, I set my kiln to candle at 170, to err on the side of
> caution rather than on the side of explosion!
> Maybe my kiln is quirky -- but it fires fine, and so I'm taking this
> route to be sure I don't blow a pot because I set the candling temp too
> high.
DJ, this is termed a "preheat", often done with clay sculptures or other
ware of questionable thicknesses.
When you program a temperature in the controller, it is reading temperature
via the thermocouple that is often covered with a ceramic sheath.
There very often is lag time between thermocouple & controller and all of
this is controlled by a thermocouple offset. All of this stuff is in the
kiln manual. This can result in the temperature going beyond your set
temperature.
In my situation, working with "S" type thermocouples and very thin ceramic
covers, I have turned off the offset to get better readings.
Understanding the thermocouple offset can be helpful if you find one area o=
f
the electric kiln firing hotter or cooler than the rest.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Jaime Salles on sat 19 feb 11
DJ=3D20
There is nothing wrong with your kiln or controller.
=3D09 Air is a poor thermal conductor, and in the end the thermocouple=3D20
can only really give you it's own body temperature, because of its greate=
=3D
r=3D20
mass in relationship to the air it lags particularly at the low temperatu=
=3D
re range=3D20
of 180 deg.=3D20
=3D09The solution to your issue lies in the ramp you set to reach 180. I=3D=
20=3D
would keep the final temp at 180-90 but slow the ramp this will limit the=
=3D
=3D20
overshoot . I use 100F. Degree ramp to reach 180F on my work.=3D20
=3D09Candling is a fine term, that comes from the fuel fired(gas) kiln worl=
=3D
d=3D20
where you light the pilots and allow the candle like flame to preheat the=
=3D
kiln.
Jaime Salles
www.jsalles.com
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