Dawne Jenelle Fowkes on sun 20 apr 97
Fellow Clayarters and NCECAites,
Well, I am now two weeks post NCECA and have had time to review my notes,
literature, thoughts, clayart email, etc. My first admission is that I
slept for almost two days after returning home. This was likely due to the
"too much information" syndrome that can occur from receiving such large
amounts of stimulus in a short time span. I can handle Las Vegas on it's own
but put NCECA with it and you have overload.
My general impression was that it was TOO LARGE for such a SMALL SPACE !!!!
I Generally, I thought NCECA was pretty typical aside from the ringing of
slot machines, cigarette smoke inhalation and large number of attendees. This
was my third conference (the previous two being K.C. and New Orleans). My
kudo's to those who had the stomach and tenacity to organize such an
event.... you'll be taking Zantac for only a few more weeks now!
The lectures were good although I enjoyed the New Orleans topics a bit
more (there seemed to be a better variety of subjects covered). I never made
it to the demo's and spoke with a few people who either loved them or were
very disappointed that they were weighted toward handbuilding or sculptural
ceramics. This is obviously reflected in the clayart postings. Seems that
the demo's reflect what the emphasis is at the particular host institution.
Does anyone else see this or am I the only one?
I missed the bus tours on Wednesday as I didn't arrive in Las Vegas until
3pm that afternoon. Unfortunately, I only got to see the Bray and the
Figurative exhibition on Saturday afternoon. We then drove to UNLV only to
find everything closed up. It was really too bad because we wanted to see
those shows and were surprised that the gallery hours weren't extended for
all of the conference days.
The highlights, I thought, were Dave Hickey's opening commentary(he was a
guest speaker when I was at Cranbrook and REALLY caused a ruckus, it was
great!), Tony Hepburn's closing, and the CLAYART Breakfast. I should also
include seeing friends, former classmates and some of the people I became
aquainted with during last June's clay conference in Helsinki.
The Clayart breakfast was TOO SHORT which made me think about throwing out
the idea of having something on a larger scale (if you listen, you can hear
Paula's voice going "Oh NOOOOOOO!!!!!!!!!"). So here's the pitch: it is
obvious that we as a group have many things to talk about online and in
person. It is also impossible to try and cover everything at breakfast in
addition to getting to know each other (especially after Joe starts
talking......don't you edit that out either!). We might take under
consideration the idea of having a pre-NCECA day and call it the ClayArt
conference (meeting, voodoo ritual, or what the group deems appropriate).
During this time we could talk about things that could be covered, up close
and personal, in more detail. The program and subjects would be determined
several months ahead of time by all Clayarters interested in participating.
Does anyone have thoughts on this??????
I enjoyed meeting many of you or at least seeing what you look like.
Vince was nice and younger than what I thought he would be. A couple of
people I wish I could have met but either missed or were absent: Jonathan
Kaplan and Dannon Rhudy. I was able to meet others in the commercial and
non-profit exhibits. Thanks to George for our clayarter "ID's" which made
this much easier.
I would be more interested in hearing about the International Ceramic
conference that may be in Canada next year???? Meanwhile, those of you who
attended the Networks in Ceramics 96 in Helsinki: if you enjoyed the
conference despite the price of attending, write Tapio Yli-Viikari at UIAH
and try to help convince him to stage another conference in 2000. I enjoyed
that one more than the NCECA's I have attended. The format was very diverse
and intense.
My apologies for going on so long.
Cheers,
Dawne Jenelle Fowkes
(My conscience got to me..... the real reason why I was arrived in L..V. so
late was because I was...... OUTLET SHOPPING IN BARSTOW... OKAY????????
I CONFESS!!!!!! I MISSED THE BUS BECAUSE I WAS IN THE GAP
OUTLET STORE BUYING A PAIR OF SHORTS I NEVER WORE BECAUSE IT WAS TOO DARN
COLD!!!!)
Karen Gringhuis on sun 20 apr 97
Dawne - Gap outlet store??! Darn - missed that one. Next time.
One comment - I am dead set against anything "pre-conference."
In other years MAJOR events (sometimes better than the mail conf. really)
have taken place pre (new Orleans DeStaebler) & post ( Minn McKenzie )
conference sometimes at a n extra charge. Given the time NCECA already
takes and the cost (too high for students IMHO), putting anything major
beofre or after makes me furious.
A Clayart b'fast would be a bit different than the aforementioned
major events but 5 days incl. travel time is a lot already.
Karen Gringhuis
Dannon Rhudy on mon 21 apr 97
Dawne,
I was there. But I had my eyes closed; no one could see me.
It WAS a bit difficult to hear names when we
introduced ourselves. Next time I'll SHOUT. Or maybe we need a
big strip of paper, write our names on with felt marker, hold them
up when it is intro time......nah. Too organized. This was for
fun. If there'd been a bit more time people could have
talked/circulated longer. Maybe introductions should come first?
Dannon Rhudy
potter@koyote.com
----------------------------Original
message----------------------------
Fellow Clayarters and NCECAites,
Well, I am now two weeks post NCECA and have had time to review
my notes,
Eleanora Eden on wed 23 apr 97
Hi Dawn and all,
While we're on admissions, I left the conference asap Saturday morning as
I had been told the roads would be impassable by noon and so I missed Tony
Hepburn's closing which I had been looking forward to alot. Any way to
get the text of this?
Eleanora....had I known there was Outlet Shopping in Barstow.....
Eleanora Eden 802 869-2003
Paradise Hill
Bellows Falls, VT 05101 eden@maple.sover.net
[the address fga@world.std.com is temporary. My mailbox at
eden@maple.sover.net still works -- do not change address books]
Paulaclay@aol.com on fri 25 apr 97
Eleanora, The test of all the lexctures, speeches and reports of all the
breakout sessions are published in a Journal. Unfortunately it doesn't come
out for many months. Paula Sibrack
Nils Lou on fri 25 apr 97
Be warned, this is long.It is essentially the material I presented at
NCECA and will likely be published in the forthcominig Journal. Nils Lou
REFRACTORY COATINGS OFFER NEW FIRING POSSIBILITIES
CGHUC-(Ceramic Grade Heat Unity Coating)
In 1963 I read about a refractory coating called Heat Unity
Coating or HUC for short. It was mentioned in a ceramic industry
publication (Ceramic Industry) claiming significant savings in fuel when
used to coat boilers and furnaces, and I wrote for information. A lot of
descriptive material was sent, even including information describing the
patent application by W.E. Holden. I filed it and didn't do anything with
it until 1975 when I went through some old files, found the folder and
decided to order if it was still available. I had just completed another
Minnesota Flat Top kiln and wanted to test HUC for its touted efficiency
by carefully monitoring the gas used both before and after application. I
found that it was still being produced by Park Chemical in Detroit and
they agreed to send me five gallons to test. Before applying the coating I
fired five times, each averaging 34 to 36 gallons of LPG.
I normally fire to cone 10 in about 10 hours holding a neutral
atmosphere until cone 010 and a medium reduction (OXYprobe .55) from there
to maturity. The HUC directions suggested application to new brick, but I
wanted to have a before and after reference and applied it to the now
slightly used interior surface. UPS delivered a five gallon steel bucket,
weighing forty pounds; the cost then was $85 plus shipping (now it is
about $100). In their directions they suggested thinning with water and
applying multiple thin coats (important). The material is a thick slurry
of silicon carbide, aluminum oxide, silica sand, calcium fluoride, calcium
oxide, sodium carbonate, sodium fluoride, glycerin and wetting agents. The
application can be by brush, roller or spray gun. I used a large
wall-paper brush and brushed it on three sides, door and roof. I thinned
it to an almost paint consistency by adding water and stirring while
brushing. (On subsequent kilns I discovered that spraying with an
inexpensive sand-blasting siphon gun was a better application method). One
coat was brushed on the roof and two everywhere else. The inside of my
kiln was now grey and I was eager to see what the results would be.
The very next firing consumed only 23 gallons of LPG. The second
used 21 and the third was down to 19! That was my most efficient fuel
usage with subsequent firings averaging around 23 gallons, a 33% decrease
in fuel consumption.
A further and unexpected advantage was the effect on my glazes.
They seemed richer and more mature, presumably because of the HUC
reflectivity similar to the glaze effects I remember getting in hard brick
kilns back in the 50s. HUC reflects infrared heat to the ware. In the
transfer of radiant energy, the measurement benchmark is the "black
body". A total black body is a substance that absorbs all the radiant
energy falling upon it. Such a substance also radiates heat energy at the
maximum rate possible by virtue of its temperature. The ability to absorb
and radiate heat energy is known as emissivity and in a perfect black body
is given as the value of one (1). The emissivity of silicon carbide at
2000F. is approximately 0.92 in contrast to insulating firebrick
emissivity values which range from 0.5 to as low as 0.2.
Park Chemical has since sold the rights to MICA Industries of
Michigan and they have taken over production producing both a commercial
grade of HUC and another for studio potters called CGHUC (Ceramic Grade).
I think this coating is well worth considering especially for potters
wanting to wood-fire and/or salt in IFB constructed kilns. Recent
experiments with salt/soda vapor firing have demonstrated the viability of
a salt-soda kiln made with IFB (insulating bricks). Hard bricks consume so
much fuel and I think a coating like CGHUC offers significant protection
to soft bricks and their use as a coating in salt kilns is definitely
worthwhile.
For example, last year Barney Knight of Sedalia, Missouri and some
friends built a wood-fired MFT kiln with recycled K-23s. They coated the
interior and kiln furniture with CGHUC, (Ceramic Grade Heat Unity Coating)
and have been successfully salting with little evidence of breakdown in
the IFB.
Earlier tests done at Western Oregon State College by Don
Hoskisson showed uncoated K-23s and K-26s holding up pretty well in strong
salting environments if not adjacent to salt dumping area. If a salt kiln
can be built with IFBs the firing cost can be reduced by a factor of four
compared with hard brick construction. Working evidence from Knights wood
fired salt kiln clearly demonstrates that K-23 construction coated with
CGHUC is a viable alternative to hard brick for salting atmospheres.
ITC Refractory Coatings
Recently I became acquainted with Feriz and Alice Delcic at
International Technical Ceramics in Florida and discovered they had
developed a group of refractory coatings that held promise for a variety
of purposes. The ITC coatings include a paste that repairs cracks and
missing chunks in both fiber and soft brick, a special coating for metal
elementsITC 213, and ITC 296A which is used in conditions where a pure,
dense surface is desired. ITC 100 is the basic all-purpose coating that
can be applied over almost any refractory surface including electric kilns
and elements!
ITC 100 is applied on the interior surface of the kiln and after
firing to set it, may be followed by a coating of ITC 296A making an
complete isolation barrier. Normally, the 296 coating is not required
except for a more dense and pure barrier. For protection of elements they
have developed ITC 213 which is designed to coat metal. This effectively
prevents element deterioration even in reduction conditions. It is best if
the elements are new, dipped in the ITC 213 mixture, allowed to dry and
then installed. ITC claims their coatings can be used as a protective
coating even on fiber surfaces significantly reducing the small particle
hazard of ceramic fiber.
Unlike CGHUC the ITC coatings are non-conductive and it is that
quality that led me to experiment with coating the inside of an electric
kiln to see if it could be a viable solution to electric reduction without
undue deterioration of the elements.
Small Electric Test Kiln for Reduction/Soda/Salt
I have long desired a small kiln to test reduction glazes at C-10
levels. Since there are many small electric kilns on the market I wanted
to see if there might be a way to use one and add gas as a reducing agent.
I chose gas because it can be accurately metered into the small kiln
environment.
Conventional wisdom and actual practice suggest that reduction
atmospheres are deleterious to and drastically shorten the life of common
elements typically found in electric kilns designed for the hobbyist or
studio potter. These elements are usually made of some alloy of iron and
aluminum (Kanthal) or the older nichrome. When heated in normal neutral or
oxidizing atmospheres they form a somewhat protective coating of oxidized
alumina which if subjected to reduction reverts to the metal and allows
the element to diminish in size and can actually spall off layers of
element material. If an electric kiln is subjected to reduction, usually
by adding carbonaceous material, it is a good idea to follow up with one
or more oxidation firings to rebuild the oxidized coating. This is not
necessary, however, if the kiln has been coated with the ITC 100. There
have been many attempts (even commercial) to produce reduction by
introducing mothballs, coal, wood, paper and vegetable oil. All work to
some degree, but the uncoated element life is inevitably shortened and
increases the firing cost considerably.
My first attempt exploring the effects of reduction on elements in
a small test kiln was at the request of Adrian Fabriano who produces
miniature pots fired to cone 10 reduction. Her first kiln was set up so a
simple 1/4 pipe could introduce propane gas as a reducing agent in the
bottom of the kiln during a firing. An opening (1-1/2) was made in the
center bottom (to introduce the gas) and another in the center of the lid
for exhaust. At 1400F propane will safely ignite and the resultant flame
can be useful for added heat. The idea was to simply let the gas combust
in the kiln chamber. Normally, the gas is not introduced until 1650F when
body reduction might be desired or for copper reds. The atmosphere was
monitored by OXYprobe and the gas metered with a simple ball valve. More
control was later obtained by adding a regulator and changing the pipe to
a simple burner. My LP supplier suggested an inexpensive rattail burner
that I modified by mounting it on a base so it could fire vertically. With
an actual burner the additional heat shortened firing time and provided
the desired reduction atmosphere. Fabriano found that she could fire 10
to 12 times before she had to change elements. This probably could have
been extended by intermittently firing the kiln without the reduction to
re-oxidize the elements.
To test the effectiveness of the ITC coatings I purchased a new
AIM electric kiln made in Corvallis, Oregon. It is their smallest design
measuring about one cubic foot in volume. I prepared it by first drilling
a burner port in the bottom and an exhaust flue in the top. Both are
simple, round holes 1-1/2 in diameter. Next I mixed the ITC100 with water
as directed and sprayed the mixture on all interior surfaces. I fired to
red heat and after cooling mixed and sprayed the ITC 296A coating.
The little AIM kiln routinely fires to cone 10 reduction in a six
hour firing with this protocol: pre-bisqued tiles or small works are fired
to 1650F on high setting in three hours using electric elements alone. The
small burner is then lighted with a pressure (bottle LPG) of 2-1/2 psi.
The OXYprobe indicates .55 to .58 on the atmosphere setting. Three hours
later cone nine is down with ten bending. Copper reds are routine. I
occasionally spray in a saturated salt/soda solution for a particular
effect. If set up in a closed studio it is important to vent even if not
reducing. My studio is quite a large space and I simply turn on an exhaust
fan built into an adjacent wall. I dont like most of the commercial
venting devices because they are costly and move too much air in my
opinion. The simplest (and cheapest) venting device Ive seen is one
developed by Mel Jacobson in Minnesota. He places a 4 steel pipe, both
ends open, next to his kiln. Brackets hold it vertically about a foot off
the floor and it goes up and out the roof . Near the top of his kiln and
out of the way of the lid hinge mechanism a one inch hole is drilled. This
hole vents the gases out and through a one inch steel pipe connected to
the larger pipe. Mel has the small pipe angling up at a 45 angle to
facilitate the venting thats it, and it works. One note: the top of the 4
pipe can be turned 90 to keep rain out.
When I bought the AIM kiln I ordered an extra set of elements and
coated them with ITC 213. After twenty firings I still reach cone 010 in
three hours electrically and so far no apparent deterioration of the
elements is observed so I have yet to replace the old elements with the
new ones to test the ITC 213 metal coating. It may be awhile.
A Salt/soda Kiln made with Insulating Fire Bricks
The ITC coatings seem just as promising as a protective coating
for IFBs in a salt/soda environment. At Hoskissons new ceramic facility at
WOSC we recently built a small salt kiln entirely with K-23s. The inside
is sprayed with one coat of ITC 100. We used a cheap sand blasting
sprayer to do the job because it handles the mixture without clogging. All
of the kiln furniture was coated as well. The kiln is well sealed because
of the coatings. Firings are showing very little deterioration of the kiln
structure using salt for sodium vapor. Salt is introduced with a length of
angle steel loaded with salt; about 15 inches is inserted and rotated to
drop the salt in front of the burners.
The coatings function, according to ITCs Feriz Delcic, as an
isolator rather than as an insulator. They set up a protective layer and
reflect the radiant heat pretty efficiently. No spalling has been observed
so far. Common cordereite/mullite shelves designed for cone six electric
kilns were coated and found to be fully functional at cone 10 in reduced
salting conditions. In order to see how well these coatings protect I
tested a matched pair of 5/8 mullite shelves in the East Creek anagama
where cone 14 is routinely achieved. One was coated with ITC 100 and the
other left uncoated. Each supported a 12 lb load set on a 10 span. After
72 hours in the hottest part of the anagama the uncoated shelf now has a
warped deflection of 1/2 versus 1/8 on the coated shelf.
While the anagama firing was in progress I decided to see how well
the ITC coating could protect non-refractory material. I cut a piece of
3/4 thick, wooden flake board about a foot larger in size than the main
stoking port and brushed on a coat of ITC 100. Cone 14 was bending and we
propped the board across the front of the port. Ten minutes later the back
of the board was still cool! After twenty minutes it was removed revealing
gases had bubbled the coating and it was only then beginning to burn.
Raku kiln made with riser sleeves and fired with a no-freeze burner
For me a raku kiln needs to be light in weight and easily
portable. 55 gallon drums lined with fiber are too bulky and not easily
lifted. Having used ceramic fiber riser sleeves as insulating liners in
kiln stacks I felt they held promise for raku kiln constructionespecially
since they are available in a variety of stock sizes. I ordered two from
Fire Brick Supply Co., each measuring one foot in height and having an
inside dimension of 18. I chose sleeves with a wall thickness of 2, but I
think with the ITC coating 1-1/2 is probably sufficient. The kiln is
constructed by simply stacking one cylinder on the other and wrapping the
pair with flexible expanded metal. I used steel, but aluminum would work.
I brazed on three pipe clamps that tighten with a screw driver so the
expanded metal screen could be snugged tight. Two handles made of 1/4
steel rod were added for lifting. The top is a slab of ceramic fiber board
(M-board) and the kiln sits on a foundation of bricks which may be hard or
soft. This protects whatever the foundation sits on and provides an
opening for the burner port that is another riser sleeve 4 in diameter.
The kiln interior, including the shelves and stilts, is sprayed with ITC
100. In forty minutes the loaded kiln reaches 1800F.
The Raku Burner
What makes this kiln truly portable is the liquid withdrawal
burner designed to use LPG in liquid rather than vapor form. This means
that a simple LPG bottle, barbecue style holding five gallons, can be used
without freezing up and losing pressure. Most propane burners, weed
burners and the like use LPG in vapor form and in order to maintain enough
Btus draw faster than vapor boils. Pressure falls and the tank freezes up.
The liquid burner, however, is designed with a sealed chamber where the
LPG is vaporized in the burner just before it gets to the orifice. Very
simple, and very effective. It requires only a liquid withdrawal
regulator, high pressure hose and a dip-tube valve installed on the tank.
I sometimes use a standard vapor tank and simply turn it upside down when
I want to draw off liquid. That way I can use it for vapor in other
applications. I dont recommend this, but I am convinced it is safe for the
small five gallon bottles.
Ceramic Fiber Kilns
One of the main objections I have with fiber kilns is the
hazardous potential of breathing fiber particles when loading or working
around them. ITC 100 sprayed over the inside hardens the surface
preventing the fibers from breaking down and becoming a permanent part of
ones lungs. With ITC 100 the kiln will likely fire more evenly and
efficiently because the coating reflects the heat and the hot face of the
fiber insulation will be cooler. Less fuel is needed to reach temperature.
I suggest spraying a coating of ITC 100, firing the kiln to normal
temperature and then spraying with a coating of ITC 296A. The total
thickness is less than 1/8. In my opinion it is a major improvement on a
fiber kiln and makes them much more acceptable.
Sources
Mica Industries (CGHUC) 313.895.4328Mike Kellie
International Technical Ceramics (ITC coatings)904.285.0200Alice Delcic
Axner Co.(ITC coatings)800.843.7057Paula
Clay Pacific Co. (Liquid propane burners) 503.876.4984Nils Lou
David Hendley on mon 28 apr 97
At 06:50 PM 4/25/97 EDT, you wrote:
>----------------------------Original message----------------------------
>Be warned, this is long.It is essentially the material I presented at
>NCECA and will likely be published in the forthcominig Journal. Nils Lou
>
>REFRACTORY COATINGS OFFER NEW FIRING POSSIBILITIES
>
Thanks, Nils, for the post - very, very interesting reading.
Are CGHUC & ITC 100 basically the same, used the same way?
Could you elaborate on the differences, if any, between CGHUC and ITC 100
-applied to fiber
-applied to soft bricks
-in heat reflection (emissivity)
-in fired physical strength
Thanks
David Hendley
Maydelle, Texas
Nils Lou on tue 29 apr 97
On fiber I would use only ITC 100 and 296. CGHUC is designed only for soft
brick and I think its major use is there. It is cheaper than ITC and is
primarily a silicon carbide based slurry. ITC is not. I don't know their
respective emmissivities, that is which is greater. CGHUC is pretty
high--around .9. I am currently comparing them in a salt vapor environment
on soft brick to see how they stand up. CGHUC is probably conductive, so I
don't recommend it in electric kilns. ITC works well in electrics. Hope
this answers most of your questions. Nils
On Mon, 28 Apr 1997, David Hendley wrote:
> ----------------------------Original message----------------------------
> At 06:50 PM 4/25/97 EDT, you wrote:
> >----------------------------Original message----------------------------
> >Be warned, this is long.It is essentially the material I presented at
> >NCECA and will likely be published in the forthcominig Journal. Nils Lou
> >
> >REFRACTORY COATINGS OFFER NEW FIRING POSSIBILITIES
> >
>
> Thanks, Nils, for the post - very, very interesting reading.
>
> Are CGHUC & ITC 100 basically the same, used the same way?
> Could you elaborate on the differences, if any, between CGHUC and ITC 100
> -applied to fiber
> -applied to soft bricks
> -in heat reflection (emissivity)
> -in fired physical strength
>
> Thanks
> David Hendley
> Maydelle, Texas
>
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