Bev Lev on sun 14 oct 07
I'm seeking some input on venting and quality of firing.=20
Some kiln buds have raised issues regarding the vent fan when bisque =
firing and "achieving a good cone 6" to prevent problems such as =
pinholing in the glaze firings. One recommends turning off the kiln =
vent several cones before the desired temperature in both bisque and =
glaze. She suggests that that is enough time for the temperature to even =
out in the kiln and prevent the much cooler bottom shelf. Most of the =
organic compounds will have burnt off long before then.=20
Well while it might sound like a sensible procedure worth trying, and is =
workable in a bisque firing.... .. I have an envirovent downdraft on a =
skutt kiln with factory drilled holes for the venting system. The =
manual says that the vent should be on above 2000 degrees F to prevent =
damage to the vent. Hence the idea of turning off the vent for the last =
couple of cones in a cone 6 firing seems ill-advised.=20
Would anyone care to venture their opinions please?
thanks=20
Bev
Maurice Weitman on mon 15 oct 07
At 11:38 -0400 on 10/14/07, wrote:
>I'm seeking some input on venting and quality of firing.
>
>Some kiln buds have raised issues regarding the vent fan when bisque
>firing and "achieving a good cone 6" to prevent problems such as
>pinholing in the glaze firings. One recommends turning off the kiln
>vent several cones before the desired temperature in both bisque and
>glaze. She suggests that that is enough time for the temperature to
>even out in the kiln and prevent the much cooler bottom shelf. Most
>of the organic compounds will have burnt off long before then.
>Well while it might sound like a sensible procedure worth trying,
>and is workable in a bisque firing.... .. I have an envirovent
>downdraft on a skutt kiln with factory drilled holes for the venting
>system. The manual says that the vent should be on above 2000
>degrees F to prevent damage to the vent. Hence the idea of turning
>off the vent for the last couple of cones in a cone 6 firing seems
>ill-advised.
>Would anyone care to venture their opinions please?
Hi, Bev,
Assuming your envirovent is the older style where the fan and motor
are right under the kiln floor, I think you should follow their
advice and keep it on.
Their newer design, and one always used by Bailey and perhaps others,
is to have the fan/motor at the end of the ducting run, on the
outside wall, both so that they stay cooler and so that the ducting
isn't pressurized with nasties.
So... if you can adapt your existing vent to mount its motor away
from the kiln, you may fire with or without the vent fan on. If you
leave it attached as is, you should follow Skutt's instructions.
By the way, although my blower is mounted on my outside wall, far
away from the kiln, I leave mine on for the entire firing... I find
no ill effects and appreciate the cleaner atmosphere in the kiln.
I also don't believe that a vent pulling warmer air from the top of
the kiln through the bottom will cool off the bottom. Your coolage
may vary.
Regards,
Maurice, laying low in Fairfax, California, trying to recover from a
cold (too much excitement with the Indians' and Rockies' wins over
the weekend) for my first view of my new granddaughter in Florida on
Thursday.
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