Dina Barnese on tue 27 sep 11
I didn't make it clear in my email that my kiln does not have a computer
controller. It has manual Low/Med/High settings and a kiln sitter.
Thanks,
Dina
Vince Pitelka on tue 27 sep 11
Dina Barnese wrote:
"I didn't make it clear in my email that my kiln does not have a computer
controller. It has manual Low/Med/High settings and a kiln sitter."
Hi Dina -
I wondered about that, and intended to give directions for both. With a
kiln-sitter kiln, just leave the bottom element on low, and prop the lid up
2 1/2" with a piece of softbrick. Shut the lid after the preheat before yo=
u
start turning up the kiln. As someone else pointed out, leaving the bottom
element on overnight uses about as much energy as leaving a couple of light=
s
on, except that leaving a couple of lights on is a waste of energy, whereas
preheating with one element on is a worthwhile safeguard and will likely
save you from some blown-up pieces.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Snail Scott on fri 30 sep 11
The received wisdom is that leaving the top peephole
in during bisque will allow the nasties to leave the kiln
during burnout. This has never seemed really likely to
me. There is, I suspect, very little air movement going on
in an evenly-heating electric kiln, and pulling out one
plug doesn't seem sufficient to change that to any
noticeable degree. IF coolness is coming in (or heat
leaving...thermodynamics or semantics)) through the
peephole (and it is definitely colder in front of an open
peephole), it would cause some convection as the cold
air sinks, driving the heat upward, making the firing more
uneven, but would any gasses really be vented? and if
they did, would it affect the general kiln atmosphere in any
appreciable way? Even assuming that the gasses produced
by burning off the organics in the clay would actually
increase the pressure in side the kiln, (a fairly leaky object
even without the peeps open), the gasses would only
vent, I assume, until the interior and exterior pressures
equalize. There is surely no force moving just the nasty
gases out of the kiln while retaining only the clean air
molecules. Is there any solid data to suggest that
significant amounts of kiln-harming (or clay-harming)
materials actually leave the kiln through an open
electric-kiln peephole? No 'somebody told me so' stuff,
but actual evidence?
(We are discussing un-vented kilns, of course.)
-Snail
paul gerhold on sat 1 oct 11
If you are venting for LOI then having top and bottom peepholes open will b=
e
a necessity so thay you promote airflow in the kiln. Power venting would
even be preferable. My guess however would be that bloating is more likely
due to firing too fast during bisque rather than kiln venting.
In a kiln without power venting having only a top peephole open will not
create air circulation. The air that exits the kiln will be from expansion
of the air caused by the rising temperature. The air will leave the kiln
whwther or not you open a peephole unless you have a totally sealed kiln in
which case it will explode. On cooling air will flow back into the kiln.
Paul
On Friday, September 30, 2011, Steve Mills
wrote:
> Dear Snail,
> UK sold Kilns, whether manufactured here or imported are required to have
a vent hole in the roof or lid.
> This is quite important as most commonly available clays here have a high
fireclay content, so a lot of rubbish is burnt out in bisque and early part=
s
of glaze firings.
> On several occasions we had customers complaining of severe bloating in
electric stoneware firings. This always turned out to be caused by Not
venting the kiln during the bisque, consequently the LOI had nowhere to go
and built up, what I can only assume is, carbon in the pot walls which
gassed during the glaze firing causing the bloats.
>
> Either way thoroughly venting the bisque by leaving the lid or top hole
open for the whole firing, is necessary in my opinion.
> Certainly the stench of Sulphur and other smells in my kiln area is very
noticeable during a bisque, such that I fire over-night to avoid it.
Personally
> I use clays with little or no fireclay in them, so that's not the only
culprit.
> I am certain that expanding gasses plus heat rising make the case for
venting very strong.
>
> Steve M
>
> Steve Mills
> Bath
> UK
> www.mudslinger.me.uk
> Sent from my Ipod touch
>
> On 30 Sep 2011, at 15:09, Snail Scott wrote:
>
>> The received wisdom is that leaving the top peephole
>> in during bisque will allow the nasties to leave the kiln
>> during burnout. This has never seemed really likely to
>> me. There is, I suspect, very little air movement going on
>> in an evenly-heating electric kiln, and pulling out one
>> plug doesn't seem sufficient to change that to any
>> noticeable degree. IF coolness is coming in (or heat
>> leaving...thermodynamics or semantics)) through the
>> peephole (and it is definitely colder in front of an open
>> peephole), it would cause some convection as the cold
>> air sinks, driving the heat upward, making the firing more
>> uneven, but would any gasses really be vented? and if
>> they did, would it affect the general kiln atmosphere in any
>> appreciable way? Even assuming that the gasses produced
>> by burning off the organics in the clay would actually
>> increase the pressure in side the kiln, (a fairly leaky object
>> even without the peeps open), the gasses would only
>> vent, I assume, until the interior and exterior pressures
>> equalize. There is surely no force moving just the nasty
>> gases out of the kiln while retaining only the clean air
>> molecules. Is there any solid data to suggest that
>> significant amounts of kiln-harming (or clay-harming)
>> materials actually leave the kiln through an open
>> electric-kiln peephole? No 'somebody told me so' stuff,
>> but actual evidence?
>>
>> (We are discussing un-vented kilns, of course.)
>>
>> -Snail
>
Steve Mills on sat 1 oct 11
Paul,
My experience does not back up your requirement for two peeps open to promo=
t=3D
e circulation. Rather I find the expansion of gasses caused by LOI combusti=
o=3D
n is sufficient for my kiln to self-vent thoroughly enough, also the introd=
u=3D
ction of cold air through the bottom peep increases firing costs, I've trie=
d=3D
it!.=3D20
In the cases of our customer's problems I checked their firing regimes as p=
a=3D
rt of my assessment, and closed lid vents were the problem, not fast firing=
.=3D
=3D20
As a matter of interest opening the lid vents caused another problem, namel=
y=3D
setting off their very efficient smoke alarms. They had to arrange for mor=
e=3D
effective ventilation of their Kiln Rooms!
Power-venting systems are pretty rare over here, largely because of the Ind=
u=3D
stry requirement for Lid and or Roof vents on Kilns in the UK makes importi=
n=3D
g them an expensive and usually unnecessary luxury.=3D20
Steve M
Steve Mills
Bath
UK
www.mudslinger.me.uk
Sent from my Ipod touch
On 1 Oct 2011, at 12:35, paul gerhold wrote:
> If you are venting for LOI then having top and bottom peepholes open will=
b=3D
e a necessity so thay you promote airflow in the kiln. Power venting would=
e=3D
ven be preferable. My guess however would be that bloating is more likely d=
u=3D
e to firing too fast during bisque rather than kiln venting. =3D20
>=3D20
> In a kiln without power venting having only a top peephole open will not =
c=3D
reate air circulation. The air that exits the kiln will be from expansion =
o=3D
f the air caused by the rising temperature. The air will leave the kiln wh=
w=3D
ther or not you open a peephole unless you have a totally sealed kiln in wh=
i=3D
ch case it will explode. On cooling air will flow back into the kiln.
>=3D20
> Paul
>=3D20
>=3D20
>=3D20
>=3D20
Bonnie Staffel on sat 1 oct 11
I can tell by the smell of the air coming out of the peep hole. =3D
Different
odors are emitted throughout the whole firing, IMO, and experience. I =3D
even
recognize the odor when the kiln is nearing completion. The nose comes =3D
in
handy in this case.=3D20
Bonnie
http://webpages.charter.net/bstaffel/
http://vasefinder.com/bstaffelgallery1.html
DVD=3DA0 Throwing with Coils and Slabs
DVD=3DA0 Introduction to Wheel Work
Charter Member Potters Council
May Luk on sat 1 oct 11
Hi Steve;
I don't believe UK kiln lids can be open for candling. It is locked
once the kiln is on, isn't it?
I was told every 1/2" of ware is 50 deg C per hour in the first 200
deg C firing. It seems to work for me and my teacher Chris Bramble. If
my wares are dampish, I might program 3 hours ramp to get to 100 deg
C. But I don't do big hunk of clay like Steve Tobin, his exploding
clay takes 2 days of candling, or something like that.
Regards
May
On Sat, Oct 1, 2011 at 11:08 AM, Steve Mills
wrote:
> Paul,
>
> My experience does not back up your requirement for two peeps open to pro=
=3D
mote circulation. Rather I find the expansion of gasses caused by LOI combu=
=3D
stion is sufficient for my kiln to self-vent thoroughly enough, also the in=
=3D
troduction of cold air through the bottom peep increases firing costs, I've=
=3D
tried it!.
>
> In the cases of our customer's problems I checked their firing regimes as=
=3D
part of my assessment, and closed lid vents were the problem, not fast fir=
=3D
ing.
> As a matter of interest opening the lid vents caused another problem, nam=
=3D
ely setting off their very efficient smoke alarms. They had to arrange for =
=3D
more effective ventilation of their Kiln Rooms!
> Power-venting systems are pretty rare over here, largely because of the I=
=3D
ndustry requirement for Lid and or Roof vents on Kilns in the UK makes impo=
=3D
rting them an expensive and usually unnecessary luxury.
>
> Steve M
>
> Steve Mills
> Bath
> UK
> www.mudslinger.me.uk
> Sent from my Ipod touch
>
> On 1 Oct 2011, at 12:35, paul gerhold wrote:
>
>> If you are venting for LOI then having top and bottom peepholes open wil=
=3D
l be a necessity so thay you promote airflow in the kiln. =3DA0Power ventin=
g =3D
would even be preferable. My guess however would be that bloating is more l=
=3D
ikely due to firing too fast during bisque rather than kiln venting.
>>
>> In a kiln without power venting having only a top peephole open will not=
=3D
create air circulation. =3DA0The air that exits the kiln will be from expa=
ns=3D
ion of the air caused by the rising temperature. =3DA0The air will leave th=
e =3D
kiln whwther or not you open a peephole unless you have a totally sealed ki=
=3D
ln in which case it will explode. =3DA0On cooling air will flow back into t=
he=3D
kiln.
>>
>> Paul
>>
>>
>>
>>
>
--=3D20
http://www.artspan.org/artist/mayluk
http://www.ceramicsbrooklyn.com/
Steve Mills on sat 1 oct 11
Dear Snail,
UK sold Kilns, whether manufactured here or imported are required to have a=
v=3D
ent hole in the roof or lid.
This is quite important as most commonly available clays here have a high f=
i=3D
reclay content, so a lot of rubbish is burnt out in bisque and early parts =
o=3D
f glaze firings.=3D20
On several occasions we had customers complaining of severe bloating in ele=
c=3D
tric stoneware firings. This always turned out to be caused by Not venting=
t=3D
he kiln during the bisque, consequently the LOI had nowhere to go and built=
u=3D
p, what I can only assume is, carbon in the pot walls which gassed during t=
h=3D
e glaze firing causing the bloats.=3D20
Either way thoroughly venting the bisque by leaving the lid or top hole ope=
n=3D
for the whole firing, is necessary in my opinion.=3D20
Certainly the stench of Sulphur and other smells in my kiln area is very no=
t=3D
iceable during a bisque, such that I fire over-night to avoid it. Personall=
y=3D
=3D20
I use clays with little or no fireclay in them, so that's not the only culp=
r=3D
it.=3D20
I am certain that expanding gasses plus heat rising make the case for venti=
n=3D
g very strong.=3D20
Steve M
Steve Mills
Bath
UK
www.mudslinger.me.uk
Sent from my Ipod touch
On 30 Sep 2011, at 15:09, Snail Scott wrote:
> The received wisdom is that leaving the top peephole
> in during bisque will allow the nasties to leave the kiln
> during burnout. This has never seemed really likely to
> me. There is, I suspect, very little air movement going on
> in an evenly-heating electric kiln, and pulling out one
> plug doesn't seem sufficient to change that to any
> noticeable degree. IF coolness is coming in (or heat
> leaving...thermodynamics or semantics)) through the
> peephole (and it is definitely colder in front of an open
> peephole), it would cause some convection as the cold
> air sinks, driving the heat upward, making the firing more
> uneven, but would any gasses really be vented? and if
> they did, would it affect the general kiln atmosphere in any
> appreciable way? Even assuming that the gasses produced
> by burning off the organics in the clay would actually
> increase the pressure in side the kiln, (a fairly leaky object
> even without the peeps open), the gasses would only
> vent, I assume, until the interior and exterior pressures
> equalize. There is surely no force moving just the nasty
> gases out of the kiln while retaining only the clean air
> molecules. Is there any solid data to suggest that
> significant amounts of kiln-harming (or clay-harming)
> materials actually leave the kiln through an open
> electric-kiln peephole? No 'somebody told me so' stuff,
> but actual evidence?
>=3D20
> (We are discussing un-vented kilns, of course.)
>=3D20
> -Snail
Steve Mills on sat 1 oct 11
Dear May,
You're right. Like I said in my previous post UK Kilns HAVE to have a vent
in either the lid, or for Front Loaders in the roof.
Government regulation required safety locks fitted to ALL new kilns prevent
"cracking" them open while the circuit is "Live".
Take care
Steve
On 1 October 2011 23:01, May Luk wrote:
> Hi Steve;
>
> I don't believe UK kiln lids can be open for candling. It is locked
> once the kiln is on, isn't it?
>
> I was told every 1/2" of ware is 50 deg C per hour in the first 200
> deg C firing. It seems to work for me and my teacher Chris Bramble. If
> my wares are dampish, I might program 3 hours ramp to get to 100 deg
> C. But I don't do big hunk of clay like Steve Tobin, his exploding
> clay takes 2 days of candling, or something like that.
>
> Regards
> May
>
> On Sat, Oct 1, 2011 at 11:08 AM, Steve Mills
> wrote:
> > Paul,
> >
> > My experience does not back up your requirement for two peeps open to
> promote circulation. Rather I find the expansion of gasses caused by LOI
> combustion is sufficient for my kiln to self-vent thoroughly enough, also
> the introduction of cold air through the bottom peep increases firing cos=
ts,
> I've tried it!.
> >
> > In the cases of our customer's problems I checked their firing regimes =
as
> part of my assessment, and closed lid vents were the problem, not fast
> firing.
> > As a matter of interest opening the lid vents caused another problem,
> namely setting off their very efficient smoke alarms. They had to arrange
> for more effective ventilation of their Kiln Rooms!
> > Power-venting systems are pretty rare over here, largely because of the
> Industry requirement for Lid and or Roof vents on Kilns in the UK makes
> importing them an expensive and usually unnecessary luxury.
> >
> > Steve M
> >
> > Steve Mills
> > Bath
> > UK
> > www.mudslinger.me.uk
> > Sent from my Ipod touch
> >
> > On 1 Oct 2011, at 12:35, paul gerhold wrote:
> >
> >> If you are venting for LOI then having top and bottom peepholes open
> will be a necessity so thay you promote airflow in the kiln. Power venti=
ng
> would even be preferable. My guess however would be that bloating is more
> likely due to firing too fast during bisque rather than kiln venting.
> >>
> >> In a kiln without power venting having only a top peephole open will n=
ot
> create air circulation. The air that exits the kiln will be from expansi=
on
> of the air caused by the rising temperature. The air will leave the kiln
> whwther or not you open a peephole unless you have a totally sealed kiln =
in
> which case it will explode. On cooling air will flow back into the kiln.
> >>
> >> Paul
> >>
> >>
> >>
> >>
> >
>
>
>
> --
> http://www.artspan.org/artist/mayluk
> http://www.ceramicsbrooklyn.com/
>
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