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u.p. hogagama 2010 wood-firing... the inventory

updated mon 8 mar 10


gary navarre on sat 6 mar 10

Hay Crew,=3D0A=3D0A Ya know this group of drunks I hang out with have this =
g they call a searching and fearless inventory (of themselves) and eventual=
ly share it with another person. Well, thank my god looking at the results =
of this first Hobagama 2010 Wood-firing has nothing to do with morality alt=
hough some of our psychiatric friends might abstract some theory of sublima=
ted sexual fantasy in firing a kiln but they are nuts anyway. So I started =
an album that deals with the load and what I did ...=3D0A=3D0Ahttp://public=
.fot=3D that we might get an idea what h=
ned in the seven days of stoking, minus the vary important long (12 hour) n=
ap with the damper closed. Feel free to comment with ideas so we all might =
learn how to tame one of these beasts.=3D0A=3D0A The first thing I need to =
running in the background of my thought is the fact this first firing had =
as much to do with cooking the kiln as it did getting any successful pieces=
to "temperature". Another factor is I was either too cheap or too lazy, or=
both, to buy two new pyrometers so I would have more accurate temperature =
readings because my old ones don't hold calibration. =3D0A=3D0A After I lit=
thing on a Thursday evening I started taking notes 2 days later when the a=
verage temperature was about 300=3DB0F. I was still getting steam off the s=
ck on Sunday. Into Monday I'd had a couple short naps and took off to a mee=
ting for a couple hours while the temperature was still hovering around it'=
s first moves back and forth through quartz conversion and I fell asleep ag=
ain for 2 hours just before Monday midnight/Tuesday morning when I awoke an=
d got into stoking until early morning at 9:30AM I thought I saw through th=
e Pig-nose the cones right up front were melted but I had 1875=3DB0F (way o=
for ^10) on the front pyrometer and 1430=3DB0F on the tail. I kept stoking=
ut seemed to loose heat until about 1:00PM and took a nap with the front at=
1755=3DB0F and the tail at 1525=3DB0F. As it turns out that is the hottest=
tail got according to the old pyrometers. I couldn't keep it up so I close=
d the damper again about Tuesday midnight and slept till
noon Wednesday. When I awoke the color was gone but the pyros were each re=
ading dead even at 1250=3DB0F so I used the coals and started another fire.=
hortly after I heard the porcelain up front popping and had to decide weath=
er to keep going again or quit and save wood. I decided to keep going becau=
se I figured I could learn more by trying to even out the temperature front=
to back and maybe raise the rest of the kiln to something more acceptable.=
Well I didn't get much hotter up front but with side and tail stoking I di=
d manage to stoke the tail to 1500=3DB0F and the front to 1499=3DB0F accord=
ing =3D
to the pyrometers. Once I got them even I had to bag it, I was tired so I s=
hut her down.=3D0A=3D0A The result of all the secondary stoking trying to g=
et h=3D
eat really only resulted in a lot of ash being deposited on shelves and in =
pots around the holes without melting. In a way that is a good thing becaus=
e now I know where the secondary stoke ash will be and can design pots to c=
atch most of it before landing on the shelving or floor. I have considered =
just replacing the pots that got wrecked up front and re-firing the rest wh=
ere they sit until I think about how much extra ash I'll be putting on the =
shelves when I side stoke again so it looks like I'll unload and clean up t=
he whole load before reloading. This would give me a chance to reconsider t=
he load density and open up the tail and mid sections of the load a bit mor=
e to the flame. I think I loaded the entire load too tight and the pots in =
the collection area at the base of the stack...=3D0A=3D0Ahttp://public.fotk=
m/GindaUP/ca/kpap/meotl/0168instack3.html=3D0A=3D0A might have interfered w=
ith =3D
the draft so I'm leaving those out next time around. I'm thinking of settin=
g a small charcoal fire in the stack to help get draft earlier.=3D0A=3D0A O=
ne m=3D
ajor fix-it is the mousehole to the Bourry box ...=3D0A=3D0Ahttp://public.f=
.com/GindaUP/ca/kpap/meotl/broken-mousehole.html=3D0A=3D0A... and in fixing=
broken cover I should also make the opening higher so more air can get to =
the coal pile and it can also be reamed out while firing of necessary. Unlo=
ading the chamber so I can stretch out and work on it from inside might be =
the ticket unless I end up with no choice and need to take the Pignose and =
the front of the Bourry apart so I can access the mouseholes. I'm glad I bu=
ilt them so I could repair them without disturbing the Bourry box to chambe=
r connection.=3D0A=3D0A The stack needs some attention and adding a couple =
ed in feet of brick with a cap damper would help pull the heat into the tai=
l too but now I'm getting tired again just thinking about all that work so =
stay in there and don't let the brown acid fool ya eh!=3D0A=3D0AGary Navarr=
Navarre Pottery=3D0ANavarre Enterprises=3D0ANorway, Michigan, USA=3D0Ahttp:=

Elizabeth Priddy on sun 7 mar 10

Your pyrometer will only indicate heat, not heatwork. It is only a gauge o=
f whether you are climbing or falling above 2000 degrees, in my experience.

Draw rings will tell you more than a pyrometer in a wood firing. Ash melt =
and accumulation will show on them where a pyrometer reading will only tell=
you if it is likely to be happening.

There are probably pyrometers out there that would give you meaningful info=
rmation to ceramic engineers, but I would doubt they exist in any potter's =

Good luck with your firings.

- ePriddy

Elizabeth Priddy
Beaufort, NC - USA

gary navarre on sun 7 mar 10

Ya Liz,=3D0A=3D0A To check for rise and fall is about all I use the pyromet=
ers =3D
for too and in the past I have gotten readings in the 2300=3DB0F+ ranges af=
r a couple three days of firing but that was when the pyrometers were newer=
. A lot of the porcelain separators are busted out, insulation burned off, =
and the calibration screw on one seems stripped. I was not using the porcel=
ain protectors either so the thermocouples have taken a beating.=3D0A=3D0A =
was also the first firing I practiced using draw rings...=3D0A=3D0Ahttp://=
... =3D
and I practiced pulling them and setting a couple back in place with a thin=
steel rod I found at Home Depot for a couple bucks. A little tweaking to t=
he handle end and it should do the job for a while. I could see there was n=
o glaze or cone melt from the spyhole so I didn't expect any when I pulled =
them. I was surprised to see a copper red blush in one of the tests so that=
is encouraging. The one mistake I made was setting them into the snow to q=
uick cool so they got wet and I missed out on an early accurate percent of =
absorption test. I baked and nuked them to see if I could dry them enough f=
or a weighing but the results were too erratic to be of value. I can tell f=
rom experience there is a fair amount of vitrification as might be seen in =
an over-fired bisque yet still pores enough to add a bit of glaze where it =
bubbled up, froze on cooling, and broke off the pot. On the other hand I mi=
ght just leave those areas bare so the pieces have that
weathered Italian Fresco look with sections of stone showing through the p=
igment. Thanks for the brainstorm and stay in there eh!=3D0A=3D0A=3D0AGary =
e=3D0ANavarre Pottery=3D0ANavarre Enterprises=3D0ANorway, Michigan, USA=3D0=
--- On S=3D
un, 3/7/10, Elizabeth Priddy wrote:=3D0A=3D0A> From:=
zabeth Priddy =3D0A> Subject: Re: U.P. Hogagama 2010 =
od-firing... the Inventory=3D0A> To: Clayart@LSV.CERAMICS.ORG, "gary navarr=
=3D0A> Date: Sunday, March 7, 2010, 8:08 AM=
> Your pyrometer will only indicate=3D0A> heat, not heatwork.=3DA0 It is on=
ly a=3D
gauge of whether you=3D0A> are climbing or falling above 2000 degrees, in =
=3D0A> experience.=3D0A> =3D0A> Draw rings will tell you more than a pyrome=
ter in=3D
a wood=3D0A> firing.=3DA0 Ash melt and accumulation will show on them=3D0A=
> wher=3D
e a pyrometer reading will only tell you if it is likely=3D0A> to be happen=
g.=3D0A> =3D0A> There are probably pyrometers out there that would give you=
meaningful information to ceramic engineers, but I would=3D0A> doubt they =
ist in any potter's budget.=3D0A> =3D0A> Good luck with your firings.=3D0A>=
=3D0A> =3D
- ePriddy=3D0A> =3D0A> Elizabeth Priddy=3D0A> Beaufort, NC - USA=3D0A> =3D0=
A> http://=3D> =3D0A> =3D0A> =3D0A> =3D0A> =3D0A> =3DA0 =3DA=
0 =3DA0 =3D0A> =3D0A=3D