Chess Denman on fri 19 nov 99
Since acquiring an oxyprobe in order to regularise my intermittent
production of reds I have lost the capacity to do so entirely!
I use a range of glaze recipies for reds including petes red and lewis red
all of which have produced reds in the past.
Before the probe I used to overgass the kiln at all stages to a massive
degree (I knew nothing about neutral firing)
I obtained reduction by closing the damper and judged it by flame at the
peep (set in the middle of the front door)
Reduction started at 1000 or a bit less on a pyrometer (though the true kiln
temp may have been closer to 900 or even 850 owing to the sight of the
probe.) and continued to the end.
often there was a bit of a race to top temp.
Firings included a 15 -30 minute soak. I did not use cones at the end but
just hovered at pyrometer measured 1270 odd. the kiln cooled normally.
Now I
use much much less gass.
get reduction with primary air down and damper
measure reduction on the probe
Firings are as follows.
oxidising to 500 odd.
about 0.08 - 0.1 on the probe till 800 or so
reduction at 800 intense 0.8
reduction down as firing proceeds to 0.5 then at the end 0.4/0.3
Part of the reason for this is because I find obtaining mild or moderate
reduction almost impossible as things seem terribly finely ballanced.
on one occasion the reduction was a bit less intense because wavery.
I fire to cone nine down ten bending which corresponds to a pyrometer
reading of 1260.
Firings take 10-12 hours as opposed to 8
"naked" reds have vanished. I get hints of red if I dip transparent over the
top.
Any suggestions
Chess
Hank Murrow on sat 20 nov 99
Dear Chess; When folks (whom I advise about their new kiln or probe) start
out, I reccommend that they fire their regular fire and just take readings
and note them in a log. Once you are sure your readings represent the fire
you expect; then, and only then, use the Oxy-Probe to govern the fire. Hope
this helps get you back on track, Hank in Eugene
>----------------------------Original message----------------------------
>Since acquiring an oxyprobe in order to regularise my intermittent
>production of reds I have lost the capacity to do so entirely!
>
>I use a range of glaze recipies for reds including petes red and lewis red
>all of which have produced reds in the past.
>
>Before the probe I used to overgass the kiln at all stages to a massive
>degree (I knew nothing about neutral firing)
>
>I obtained reduction by closing the damper and judged it by flame at the
>peep (set in the middle of the front door)
>
>Reduction started at 1000 or a bit less on a pyrometer (though the true kiln
>temp may have been closer to 900 or even 850 owing to the sight of the
>probe.) and continued to the end.
>often there was a bit of a race to top temp.
>Firings included a 15 -30 minute soak. I did not use cones at the end but
>just hovered at pyrometer measured 1270 odd. the kiln cooled normally.
>
>Now I
>use much much less gass.
>get reduction with primary air down and damper
>measure reduction on the probe
>Firings are as follows.
>oxidising to 500 odd.
>about 0.08 - 0.1 on the probe till 800 or so
>reduction at 800 intense 0.8
>reduction down as firing proceeds to 0.5 then at the end 0.4/0.3
>Part of the reason for this is because I find obtaining mild or moderate
>reduction almost impossible as things seem terribly finely ballanced.
>
>on one occasion the reduction was a bit less intense because wavery.
>
>I fire to cone nine down ten bending which corresponds to a pyrometer
>reading of 1260.
>
>Firings take 10-12 hours as opposed to 8
>
>"naked" reds have vanished. I get hints of red if I dip transparent over the
>top.
>
>Any suggestions
>Chess
Stephen Mills on mon 22 nov 99
Go back to the old technique and measure what's happening while you are
firing, and use cones as well!
Steve
Bath
UK
In message , Chess Denman writes
>----------------------------Original message----------------------------
>Since acquiring an oxyprobe in order to regularise my intermittent
>production of reds I have lost the capacity to do so entirely!
>
>I use a range of glaze recipies for reds including petes red and lewis red
>all of which have produced reds in the past.
>
>Before the probe I used to overgass the kiln at all stages to a massive
>degree (I knew nothing about neutral firing)
>
>I obtained reduction by closing the damper and judged it by flame at the
>peep (set in the middle of the front door)
>
>Reduction started at 1000 or a bit less on a pyrometer (though the true kiln
>temp may have been closer to 900 or even 850 owing to the sight of the
>probe.) and continued to the end.
>often there was a bit of a race to top temp.
>Firings included a 15 -30 minute soak. I did not use cones at the end but
>just hovered at pyrometer measured 1270 odd. the kiln cooled normally.
>
>Now I
>use much much less gass.
>get reduction with primary air down and damper
>measure reduction on the probe
>Firings are as follows.
>oxidising to 500 odd.
>about 0.08 - 0.1 on the probe till 800 or so
>reduction at 800 intense 0.8
>reduction down as firing proceeds to 0.5 then at the end 0.4/0.3
>Part of the reason for this is because I find obtaining mild or moderate
>reduction almost impossible as things seem terribly finely ballanced.
>
>on one occasion the reduction was a bit less intense because wavery.
>
>I fire to cone nine down ten bending which corresponds to a pyrometer
>reading of 1260.
>
>Firings take 10-12 hours as opposed to 8
>
>"naked" reds have vanished. I get hints of red if I dip transparent over the
>top.
>
>Any suggestions
>Chess
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Tel: **44 (0)1225 311699
Fax: **44 (0)870 0526466
| |
|
