Kaowool lining.
Russell Andavall
a less costly firing. As many know, who have read and heard, the west
coast of the US is experiencing an energy crunch. The crunch, for now,
consists of rising prices for natural gas and propane. Obviously, those
of us who make pottery for a living have to redesign and modify our
kilns for the most efficient use of natural gas, if we are to stay in
business. Last year, I spent about $2500 on natural gas to produce about
$25,000 worth of product. There are several other expenses involved in
production as well. Rent on my studio, running my truck, electricity and
clay, glaze materials as well as maintenance upon my shop space as well.
For natural gas prices to double or triple and worse yet, to not be
available, would be a serious blow to my lifestyle as a production
potter. So, I have to look at lining the kilns with kaowool and
increasing the efficiency of my burners first. I have bought two rolls
of inch thick kaowool blanket, some pieces of nichrome rod, and some
kiln cement. I plan to line the side walls of the kiln and the back wall
of the kiln. The trickiest part of the operation will be securing the
blanket to the wall of the kiln with the nichrome rods and wire. I
decided not to attach the kaowool directly to the ceiling of the kiln
because the kaowool tends to flake off after a while and drift onto the
pots. Instead, I think that laying strips of the blanket upon the roof
of the kiln will give the kiln additional insulation. I am lining the
potion of the kiln above the bag wall on the sides where the burner
ports are. I am lining the entire area between the bag walls on the back
wall. I am lining the area between the bag wall and the door. The door
is a brick up door and I seal the top with a kaowool blanket as well. I
don't know of anything to do with my burners. I have 8 eclipse burners
on this monster. Currently, the firing pattern takes about 20 hours to
fire. I start with the burners on low over night to get to red heat in
the morning. I know I am going to have to watch my firing pattern until
I figure out how the extra insulation will affect the firing times and
the amount of fuel to use. I have babbled on for long enough, I would
welcome comments and suggestions by knowledgeable folk. That is kiln
builders.... and some experiences doing this stuff...
Russ Andavall
www.firegodarts.com
Steve Mills
Whatever you do make sure you coat/spray the Fibre with colloidal
silica, known over here as Rigidiser (W) which gives the Fibre an
abrasion resistant surface, much needed when using gas burners. This
stuff is manufactured by the makers of Fiberfrax, and is particularly
effective as it combines WITH the Fibre, rather than sitting on top like
so many other treatments. Like all treatments it will need occasional
re-application. Its advantage in this case is it doesn't fall off taking
bits of fibre with it!
Usual disclaimers
Steve
Bath
UK
In article <3A77C487...@pacbell.net>, Russell Andavall
<anda...@pacbell.net> writes
--
Steve Mills
Bath
UK
Slgraber
also - in theory there is more of a heat loss thru the 4 corners of <what i
figure is> your box shaped kiln then on the regular walls. whatever scrap you
gain from your refurbishment should be added to these corners to take up what
is usually unused volume.
did you say you were also applying cloth to your bag walls too? i would, even
if you separated some of the layers to apply a smaller thickness here. these
bag walls absorbe heat -- form the job of deflecting flame -- that would
otherwise go into the pieces. they're kinda like giant ice cubes on the scale
of things.
it's likely time to fine tune those 'rules of thumb" we all use on port
openings and flues sizes. maybe you can slowly choke off your burner ports
SLIGHTLY each fire to reduce the amount of free air also going into the kiln.
no sence heating up additional air. maybe you can rig something to draw air in
along side your flew for some free heat? i doubt it -- but if you had a way to
pre-heat air before it goes into the kiln it'd help.
i feel for you. i'm in southern california and i have stalled on building my
kiln until i see things settle out. i don't know if it'd be best to go with
natural gas or propane - or a hybrid of both. certainly NOT electric.
maybe it'd pay you slightly to candle overnight along with a propane bottle
burner or just propane? chances are although it's "red" in the morning it
might have reached a suitable "red" at 3:36 in the morning and just sat there
until you got there to do another adjustment. i don't think propane has jumped
as much recently as natural gas.
in the world of propane there is a classification difference that occurs at 500
galons - so most of those big bottles are 499 gallons to stay under that level.
maybe rig up to go both ways?
paying for the cloth is an investment - worthy business desicion. maybe a
computer firing system is in order now too? i have no clue what they cost.
does it suit your work to lower to cone 6 or cone 5 from cone 10?
of course re-looking at the inventory you fire is useful to make sure what IS
fired is SOLD fast.
i've started playing with racu recently but i'm not paying the bills with clay
anymore these days (so far - the company had a layoff last week). maybe you
might shift a line of work toward low fire?
good luck and post again.
see ya
steve
>Subject: Re: Kaowool lining.
>From: Steve Mills steve...@mudslinger.demon.co.uk
>Date: 1/31/2001 2:47 AM Pacific Standard Time
>Message-id: <RQeDnWA7...@mudslinger.demon.co.uk>
steve graber
Russell Andavall
Dear Steve Garber and all:
Thanks for the suggestions as to how to improve my kiln. I don't like the idea
of lining the bag wall because the bag wall breaths flame thru to the pottery in
the bottom shelves. I am lining the corners of the kiln. The main problem that I
face is how to attach the kaowool to the wall of the kiln. I will take pictures of
all I do and share what I learn on my website.
The carbonation system for natural gas kilns is fairly primitive, but
effective. I run the burners in blue flame all the way thru the firing. This seems
like the weakest area of what I do and I would love to see some innovative burner
designs. Reduction is achieved by pushing in the dampers restricting the exit
gases from going out the flue and into the stack. I stay up all night the nights I
turn the kiln up. I am up at 3 am.... and at 6 am.... start at 7 pm. turn up at
midnight, turn up at 3 am and turn up to full at 6 am. red heat (08) at 7 am and
body reduction for 45 minutes. Pull the dampers after that and leave until the
kiln reaches cone 10. I then put the kiln into full glaze reduction ( usually
about 2 pm) The kiln stays in full reduction for 2 hours. Then I pull the dampers
back out and see how even the firing is top to bottom. I let the kiln go up to
cone 11 in the middle and at least cone 9 on the bottom. Most of the time, the
kiln is even and has reached an ideal state of cone 11 on the top and middle and
cone 10 on the bottom with even reduction through out the firing as evidenced by
the finished product unloaded a few days later. Occasionally, I have to push the
kiln temperature up on the bottom by adding more gas and air to the burners to
push the heat in the middle to the bottom...
I love my high fire glazes and will try and stay with them. I fire to cone 11
in the middle and cone 10 on the bottom and cone 11 on the top of the kiln when
things are working ideally. Using propane seems like a good idea for country
firing, but propane is more expensive than gas in the city. I do use propane for
raku firings. I only do raku for my own enjoyment as the pieces do not sell
commensurate to amount of labor involved. Hell, functional mugs and bowls barely
do that. Economically, pottery making does not make one hell of a lot of sense any
way....
If I have to get a job to support my lifestyle as a potter... well, I guess I
will. I tried to teach school in the early 1980’s when my rent doubled and I had a
wife with a teenage step daughter. The teaching drove me nuts and the extra work
load killed my relationship.... After the end of the relationship, I also quit
drinking and found enough money in my pockets each month to pay the extra rent....
This new challenge will test my resolve to remain a professional potter. Thanks
for the help and the suggestions.
Russ Andavall
The FireGod
www.firegodarts.com
David Martin
<3A77C487...@pacbell.net>:
>I am attempting to line my large high fire kiln with kaowool to achieve
>a less costly firing. As many know, who have read and heard, the west
>coast of the US is experiencing an energy crunch. The crunch, for now,
>consists of rising prices for natural gas and propane. Obviously, those
><snip>
I've a ceramic engineering background & know a little about kiln design.
I've a few suggestions that may help save some fuel cost:
1) Exterior insulation is as effective as interior insulation, and is a LOT
cheaper. Sure, you must use more because the kiln's outside is bigger than
its inside, but you can use home fiberglass insulation which is about free
compared to Kaowool.
The first time you fire a kiln covered with fiberglass it will stink as the
fiberglasses binder burns off. Don't use paper covered insulation.
The upper service temperature of fiberglass is about 950F. When it gets
hotter than that it'll collapse as the fibers shrink. So, if you put too
much on the kiln, it'll automatically adjust its thickness so the
temperature at the interface between the brick and fiberglass is 950F.
You can also use pearlite or vermiculite from garden supply shops. The
upper use temperature of these is about 1800F. These are pourable, hence
aren't as easy to apply as a fiberglass blanket. One can built sheet metal
walls to hold the external insulation in place. This has other beneficial
effects.
One way you can hurt your kiln insulating the outside is if you cover
structural steel with too much insulation, causing the steel to get weak or
oxidize. Another way exterior insulation can hurt the kiln is if there's a
layer of insulating brick on the outside of the original kiln that gets too
hot after being insulated by the fiberglass. This is seldom a problem since
most kilns have only type of softbrick.
2) An easy way to gain some efficiency (maybe 10%) is cover the kiln's
surface with something shiny. I've had good success with aluminium foil
and with aluminum sheets discarded by newsprint presses. Shiny surfaces
reflect heat back into the kiln. No joke. It is the same principle as
putting low emissivity coatings on the interior surface of the kiln wall.
Any dead white, non reactive powder will do. Pure alumina powder for
example.
3). Plug the leaks and control the fuel/air mixture closely. It should be
neutral at the base of the stack. Ay excess fuel is wasted, and any excess
air is just heated and takes the heat with it out the stack. If you are
feeding twice as much air as needed, the kiln can get only half as hot.
Russell Andavall
Thanks to all for the advise on lining the kiln with kaowool and how to
attach the wool to the brick walls. I was able to use kiln cement and some
wires to attach the wool to the walls of the kiln. I also put a layer of
wool blanket on top of the roof of the kiln as well. I spent about $400
total to do this project. I just fired up a glaze kiln this week. I used a
160 therms of gas to fire the kiln to cone 11. Each therm costs
approximately $1.78. That is the price now... last December the price was
$0.85/them and a year ago it was $0.65/therm. I was using about 200 therms
to fire this kiln to cone 11. So I am saving about one third on the amount
of gas firing with the new lining. This should pay for itself in two
firings... At approximately, $400 to do a bisque and a glaze for 100 cubic
feet of pottery that I sell for approximately $2000, I will have to
consider trying to raise the gross profits for my production to cover the
additional energy costs. I think I can still stay in business as potter
with the lining of the kilns as long as gas and electricity don't double
again!!! We have seen what has happened to gasoline in the last 10 years.
At any rate, I am also considering building a new kiln out of softbrick and
kaowool in the near future. This might be the final answer to making a more
efficient kiln to stay in business. There are other problems as well... my
truck is having problems passing smog regulations here in California as
well and I really don't have $30,000 for a new efficient truck to haul
pottery in.... Rebuilding the motor is not appealing work for me, but
potters have to be more than potters as well all know. So this month, I am
going to be a truck mechanic potter...
I made a quicktime movie and put it on my website for people to see
what I am doing to stick the kaowool to the wall of the softbrick kiln. Its
at:
http://members.tripod.com/~andavall/QTKilnLin1.html
The quicktime movie is 1200k and will take 10 minutes to download to your
computer on a 56k modem... a few seconds on DSL. The quality of the movie
is poor, so I could get it on the web at all, but it does show what I am
doing. So, if you have need to do this kind of work on your kiln, take a
look.
>
> Russ Andavall
> www.firegodarts.com
la...@rncind.com
The soft brick will stand up to the heat great but theire are other
insulation that are much cheaper than Kaowool .
Larry Clark
Slgraber
the wear loaded the same? are there nooks and crannies that you can add
trinkets? i did pretty good selling "dumb" faces that fit perfect in between
vases and bowls. maybe you could do similar? or you might already be doing
that.
i would slap clay on a styrafoam wig head and let it dry in the sun for a few
minutes, pull it off and make more. stinking easy! glue a string on the back
of the eyes to hang up. i usually sold enough to cover booth fees with these
faces alone.
maximize your volume with product.
>Subject: Kaowool lining Report on progress...
>From: Russell Andavall anda...@pacbell.net
>Date: 2/11/2001 10:34 AM Pacific Standard Time
>Message-id: <3A86DB0D...@pacbell.net>
steve graber
Russell Andavall
goblets or large vases or pitchers and I had a lot of small bowls. I normally
stack the kiln with 300 tiny vases that are no bigger than the tip of your
finger. These are made to pay for the cost of the firing... My miniatures sell
for $2 each and 3 for $5.... I sell out of them... Overall, the cost of making
and selling pottery has risen substantially in the last year. I have done the
analysis of costs and I have to say that a kiln produces between $2500 and $3000
worth of ware that costs about $1800 to produce.... this includes studio rental
as still the most costly of the expenses (about $900 per kiln) and firing with
gas of about $400 for a bisque and glaze. Clay and glaze are cheap at about $200
per kiln. Running my truck to market and getting clay is about $300 per month or
about $400/ kiln. Most years I produce 8 loads of glazed ware. Some years, I
produce an extra 9th load and some years, I have a lot of seconds.... (like if I
have to change ball clays or feldspars or something is wrong with one of the
materials.) Anyhow, I can see that I have to raise my prices about 20% if I am to
stay in business at all. I also have to market the work and I am not sure that if
I raise my prices, that I will make 20% more in sales... But hey now, I am not
alone in this... I have a friend with a restaurant/ greasy spoon that has the
same problem. I know that this thing is going to effect the whole economy.. what
tax break... getting off the topic... I guess, I have to look at better marketing
for my ware at better prices too. Hey, if I could sell my work for three times
the price, no problems... right... unless of course, we can't get gas at all...
Russ Andavall
www.firegodarts.com
Nikolaus Oppermann
...
> I have done the
> analysis of costs and I have to say that a kiln produces between $2500 and $3000
> worth of ware that costs about $1800 to produce.... this includes studio rental
> as still the most costly of the expenses (about $900 per kiln) and firing with
> gas of about $400 for a bisque and glaze.
Hi, Russel,
For me, your costs of fireing seem to be ---extremley high,---
but I don`t know the exact "used volume" of your kiln in "centimeter"
(I`m german, I`m not used to "Inches and foot")Please tell me!
My 300 liters "really-used- volume" fiber/gas kiln, takes about 40
kubic-meters of natural gas
per glaze-fireing. I`m connected to the towns natural-gas pipeline, and
I`m fireing it
50 times a year (= 15 000 liters/year). Cost of gas: 450,- $/ year 1997
My fireing cost for one 1300 C° glaze-fireing, approximately ( 1 $ = 2
DM)
gas 40 m3: 25.- german mark
Kiln-worth-reduction: 37.50 ( 15 000 ,-/ 400 fireings ?)
----------------------------------------------
total: 100,00 DM (=50 $)
price/ liter/ware : 0,33 DM
Trying to set my kiln with ware in an economic way,
I`m using a range of special sized thin 3-4 mm shelves (for dishes,
plates...)
related in size to my bigger "main"-shelves, so 2 or 3 of them do fit on
a big shelf.
Enough quality!-props in different usefull heights: very important!
Also very useful ceap and economic is the trad. technic of raw-glazing:
No bisque-firing, only glaze-firings!
Special raw-glazes (not easy to handel!)are necessary, and pots have to
be turned
very properly, because when beeing glazed,they become very week, and may
collaps.
This trad. german "Brown Stuff" pottery, I suggest in the newsgroup
above, is working this way,
and me, I learned, how to do this job.
... Nikolaus Oppermann, Hannover, Germany.
Jay Jensen
would be to change your burners to forced air, It could be expensive but
you could save gas. Go to www.wardburner.com