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wood kiln firing
techniques & tips
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plans and instructions
for making a wood-fired kiln
and firing with wood
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Wood Kiln Firing Techniques & Tips
Plans and Instructions for Making a
Wood-fired Kiln and Firing with Wood
Since humans first began to understand how fire hardened clay, we have been making ceramics, both in pits and
in wood kilns. Now, with so many fuel options available to the potter, wood-fired kilns are more of a choice than a
necessity. While wood firing isn’t easy, the results are incomparable. The work in wood kilns reveals the story of
the firing, with pieces showing ash deposits and the path of the flame through the kiln. But not all wood kilns are
built alike. Some are made for flashing from the flame, some are made for melted rivulets of ash and others still
are designed to bury the ware in ash and make it crusty and craggy. Regardless of your wood-firing aesthetic, the
wood kiln plans and diagrams in this helpful guide will show you several ways to get started understanding and
building wood kilns.
Wood Firing Basics
by W. Lowell Baker
Each wood kiln has its own firing characteristics, but there are some basic principles that hold true for any kiln
using wood as fuel. Getting the basics right means better chances for great results
Gayagama Kiln Build
by Shana Angela Salaff
Gyan Daniel Wall is a ceramic artist who builds wood-fired kilns using an ancient Middle-Eastern bricklaying
technique developed for creating vaults and domes on houses and mosques. Shana Salaff documented the
process this July at the Gaya Ceramic Arts Center in Bali, Indonesia.
Hai Kaburi: Creating Consistent Crusty
Wood-Fire Results
by Lee Middleman
If you want crusty pots in a wood-fired kiln, you almost have to put them in or near the firebox, where they will
be exposed to a lot of ash. This kiln design puts the firebox on top of the ware chamber, so the entire kiln load is
exposed to ash as if it were in a firebox.
The Manabigama
by John Thies
A cross between an anagama and a groundhog-style kiln, the manabigama is a wood kiln that’s within everyone’s
reach. Small, compact and simple to fire, this wood kiln can be fired by one person in a matter of hours—not days.
Wood-fired Raku Kiln
by Nesrin During
Wood firing isn’t just about high firing. You can build a simple raku kiln and fire your work with wood to get
stunning results. Nesrin During constructs a simple kiln that’s easy to stoke and reaches raku temperatures
without a lot of effort.
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Wood Firing Basics
Wood burns in two distinctly different stages.
The first, and most obvious, is the burning
of gasses produced when wood is heated.
Wood begins to gasify at about 500°F. The
second is the burning of the charcoal. This happens, for
the most part, after the materials that form the gasses have
been driven out of the wood. The coals in your ash pit
serve to provide some heat to the kiln and to gasify the
freshly stoked wood, mostly through radiant heat energy.
As the gasses burn in a wood kiln, they typically produce
very long flames. These flames can be easily over 30 feet
long. Charcoal produces very hot, but very short, flames.
The flame from charcoal is normally less than a few inches
long. All of these issues are relevant to building and firing
any wood-burning kiln.
One of the demonstrations I take my students through
when we begin talking about kiln design is to bring an
oxygen-acetylene torch into the classroom. If the torch is
ignited with only acetylene (fuel), it produces a very long,
very dirty flame. One can quickly pass his or her hand
through this flame without any real danger, but it will be
covered with black soot. As oxygen is added, the flame
shortens and becomes significantly hotter. As the flame
shortens with the changing oxygen-fuel ratio, smaller
flame tips appear in the center of the flame. This is the
place where the flame is the hottest. The more defined the
tips are, the hotter the flame. You want this part of the
flame in the firing chamber of a kiln, not in the firebox or
the flue.
If you have a small kiln and a fuel that develops a long
flame, you need to either redesign your kiln to use the
length of the flame, or simply shorten the flame to bring
the hottest part of the fire back into the chamber where
the pots are stacked. As with the acetylene example, the
by W. Lowell Baker
Each wood kiln has its own characteristics for firing, but there are some basic
principles that hold true for any kiln using wood as a fuel.
easiest way to shorten the flame and make it hotter is to
add oxygen.
If you have electricity at the kiln site, adding a blower
is one of the easiest and most controllable ways of adding
oxygen.
A small squirrel-cage fan that will deliver about 100
cubic feet of air per minute will supply all the air you
will need to fire a small kiln. You can fabricate a bolt-on
connector to attach the pipe to the blower, or duct tape
a piece of automotive tail pipe to the blower. You should
realize that the end of the metal pipe will be subjected
to a great deal of heat and will have to be replaced after
a number of firings. Place the pipe in the ash pit of your
firebox and adjust the air-input damper to the desired air
flow. You will find that the flame around the blow pipe
will be very intense. This system will allow you to fire
your kiln with a much smaller firebox than would normally
be needed in a natural-draft kiln. The smaller firebox
will require more frequent stoking, simply because it will
not hold as much fuel as a larger box.
Increasing the flue height would be the last choice in a
small kiln. If you do this, you must be certain that you
have air intake ports and a flue cross section large enough
to allow easy circulation of hot gasses. A damper will be
essential for control. This will be less responsive than a
forced-air system and will vary more due to atmospheric
conditions, because it depends on lowered pressure to
bring air into the kiln.
So, more air shortens the flame and more air increases
the temperature of the coal bed to help gasify your fuel
more quickly.
W. Lowell Baker is currently Professor of Art at the University of Alabama,
and has taught workshops for nearly 40 years.
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Gayagama Kiln Build
The Australia- and New Zealand-based Gyan
Daniel Wall heard of the Gaya Ceramic Arts
Center in Bali, Indonesia when he met its director,
Hillary Kane, at a wood fire conference in
Tasmania last year. Already planning to visit Bali, Wall
ended up spending much of that trip at the Gaya studio,
making pots and helping to fire their first wood kiln. This
year, he was invited back as interim director and to facilitate
the building of two more wood-fired kilns at the
center’s new studio location. The first of these was an
anagama and took form during a one-week kiln-building
workshop followed by a two-week pottery making and firing
workshop.
During the first week of July, Wall and participants in
the workshop built the Gayagama. For this kiln, Wall used
a Middle-Eastern bricklaying technique where arch bricks
are laid diagonally against each other, causing each brick
to be supported by the one underneath it. Thus, aside from
two temporary forms used to support the front and back
by Shana Angela Salaff
1
4
arches, no internal support was needed. The Gayagama
was primarily constructed from raw handmade bricks
made from local materials. The combination of the use of
raw bricks and the self-supporting arch technique enabled
the build to be closer to the kind of fluid and intuitive process
that one associates more with making ceramic vessels
than with kiln building. Though Wall’s basic plan called
for the general dimensions of the kiln, many decisions
were made on site. The result is a beautiful, organic-looking,
and well-functioning kiln.
Origins of the Technique
When asked about the origins of the technique, and
how he came to use it, Wall explained, “As far as I am
aware, Australian wood-fire potter/kiln builder Daniel
Lafferty was the first to use this technique for building
kilns in modern times. The building technique is
originally from the Middle East and is used for building
brick domes and vaults without the aid of a form-work
2 3
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1 Loo Jia Wen (l) and Tok Yu Xiang (r) learning how to
form bricks using wooden molds, then refining them.
2 Subfloor, firebox, and base of wall.
3 First four courses of raw bricks built up on the subfloor.
4 Laying in the floor using hard brick placed on a thin
layer of silica sand.
5 Creating the back arch using a bucket for support.
6 Setting up the first 45°-angle course off of the back
arch.
7 Laying in the first courses off the back arch.
8 View of completed back arch, beginning of the roof,
and walls with built-in side stoke holes.
9 Loo Jia Wen (l) and Bruce McWhinney (r) building the
front arch.
6
7
8
structure. Daniel came across this technique in a book called
Ceramic Houses, written by Nader Kalili, and decided to
translate it into kiln building. However, recently while researching
kilns on the Internet, I came across an image of an
ancient kiln in Thailand that also used this building method.
“Daniel is a close friend and mentor. I first met him and
experienced his kiln-building techniques at the Hyperclay
Gulgong event in 1998. I helped on a raw adobe brick anagama
build that he facilitated at the Tanja wood-fire event in 2002,
hosted by Yuri Wiedenhofer who had also built his kilns using
this technique. I loved this simple free-form style of building
using raw, handmade bricks, so that when it came time to build
my own kiln that was the way to go.”
The building method appeals to Wall on many levels, and fits
with his clay working methods and philosophy. “In my work
in general, I love the feeling of freedom and the sense of selfreliance
and connectedness I get from using minimal technology
and sourcing materials from nature,” he explains. “I love engaging
in the creative process in a very earthy and holistic way.
I love the free-form style of building that this method allows; it
is like making a big pot. The form evolves and unfolds during
the building process. To me, working with raw materials, making
work, designing, building, and firing kilns are all part of an
integrated holistic co-creative process.”
The Building Process
Before the build began, a typical Balinese–style tile roof
was built over the kiln area. The dirt under the kiln, well
compressed ahead of time, was graded at a slope of about 15
degrees. Staff at the Gaya CAC made over 900 bricks that
were set out to dry —as much as the Balinese humidity would
allow. During the workshop, participants learned how to
make bricks, and added these to the stockpile (1).
Wall used kiln shelves and a center string line to map out the
floor plan of the kiln and then created a sketch with the measurements.
Once the workshop started, the kiln building began
with digging in the footings for the walls and the steps for the
floor, making the base of the kiln lower than the earth around
it, creating natural insulation and support. The front and sidestoke
firebox areas were dug out even lower to create underfloor
air grates, with a duct running under the floor from the
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9

12
firebox to the side-stoke that provided pre-heated air.
Local soft red bricks were used for the foundations and
air grates of the fireboxes. These were laid with mortar
made from the earth excavated out of the floor (2). In
keeping with his philosophy of continual experimentation,
and because there was a surplus of red brick available,
Wall decided to use these extra bricks as an external
support wall that was completed after the main walls were
built. The chimney and walls were started using the raw
brick and brick mortar, and the kiln grew in many directions
at once.
When the walls were a few courses high (3), the hard
firebrick floor was laid out on a thin bed of silica sand
(4). Wall wanted the floor to be made from durable hard
brick, and for the floor to be separate from the walls so
that it could be replaced in the future if needed. Next, the
red brick outer wall was built up, along with the base of
the chimney.
Once the area between the chimney and the back of the
kiln was high enough, the back arch was created, using a
bucket as a temporary arch support (5). Raw bricks were
10 11
13
shaved down on two sides to create tapered arch bricks.
Spaces between the bricks were filled with mortar and then
well compressed. The front arch was formed in the same
way later in the process. After the key brick for each arch
was hammered into place, the supports were removed.
Once an arch was in place, the first arch course was laid
diagonally over it at a 45-degree angle, with small chunks
of brick filling in any large gaps (6). The second course
of the back arch was laid in, supported by the first course
and the side walls (7). Each successive course was staggered
over the one before it. Side stoke holes were created
(8) and blow holes were placed along the spine of the kiln.
The front arch was built next. (9). The plastic bucket supported
the structure until the key brick was inserted (10).
The chimney was built using raw bricks laid in a circular
pattern (12), with a slot created for a kiln-shelf damper.
The brick above the slot was keyed in place so that it
would never sag or bulge outward.
The staggered, self-supporting courses built off of the
front and back arches met in the middle with one final key
brick (13). This created a strong barrel vault with a beauti-
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14

10 Gyan Wall and Bruce McWhinney finishing
front arch.
11 The roof is formed by laying in angled rows
against the front and back arches.
12 The chimney is made of the same bricks, laid in
a circular pattern. The damper is a kiln shelf.
13 Gyan Wall closes up the central arch from the
inside.
14 The top view of the kiln after closing central
arch.
15 The interior of the finished kiln, coated with a
thin layer of clay and alumina hydrate.
16 Plaster is mixed by foot, then coated over the
raw bricks above the courses of red bricks that
lined the lower portion of the wall.
17 Here Loo Jia Wen (l), Bruce McWhinney (c), and
Gyan Wall (r) apply a layer of plaster.
18 The finished kiln showing the stonework outer
wall. The pizza oven can be seen between the
chimney and the back of the kiln.
15 16 17
ful herringbone-like pattern (14). Final details that were
added to the kiln included a pizza oven built between the
back of the kiln and the chimney (over the back arch and
first courses). The mortar around all bricks, both inside
and out, was compressed as much as possible, and the
interior of the kiln was washed with a thin mixture of clay
and alumina hydrate (15). Once the kiln was essentially
complete, insulating plaster was mixed by foot. Three layers
of plaster were spread over the kiln (16–17), for a total
thickness of about 6 inches (15 cm). Wall added stonework
around the kiln that is both functional—providing
steps to climb on to see through the air holes and further
buttressing for the walls of the kiln—and aesthetically
pleasing (18).
Kiln Blessing
Because the kiln is in Bali, local custom must be followed.
The Balinese, mainly Hindu, believe the gods must
be given the correct offerings and prayers for any project
to succeed. From rice fields to houses, vehicles to tools,
marriages to cremations, the proper ceremonies are necessary.
The Gayagama blessing took place on a drizzly day,
with the local village priest and an assistant presiding.
Blessings include fruit, flowers, food, baskets, and other
forms woven from banana and palm leaves.
Following the kiln-building workshop was the making
and firing workshop. Wall kept a small fire going
inside the kiln to dry out the bricks and plaster during
the first week. After a week of making, pots were loaded
green into the kiln; both kiln and contents were fired
together. The firing took three days and culminated in
a pizza party on the last night. At the end of the firing,
the firebox was filled with fuel and the dampers were
closed for an intense reduction. After about six hours, (at
about 1050°C), Wall re-stoked the kiln and then introduced
a small amount of water and a little more air to
re-oxidize the iron and to coax a rich red color out of the
pots. Most of these pots were made with a red clay/ball
clay blend that Wall has christened “Bali Bagus” (bagus
means “good” in Bahasa Indonesian).
the author Shana Angela Salaff is an artist and instructor living in Fort
Collins, Colorado. In addition to contributing to Ceramics Monthly,
she has written for Pottery Making Illustrated.
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18

Hai Kaburi
Creating Consistent Crusty Wood-Fire Results
by Lee Middleman
Matsumiya Ryoji, a master potter living
in Aomori prefecture, Japan, has developed
a unique wood-fire kiln to consistently
create ceramic pieces with a very
crusty ash surface. He achieves this by burying the work in four
successive layers of ash during the firing.
During his more-than-thirty-year career, Matsumiya has built fourteen
kilns and fired them more than 750 times. He currently has two
noborigamas, an anagama with two additional chambers, an Olsen
crossfire, an archaeological Sueki, and his new bourry box hai
kaburi (ash covering) kiln.
Matsumiya was seeking a way to achieve work similar
to the few pieces created in the rebox of his anagama. In
the firebox, only a small area is effective and the work
is subject to damage from stoking. The anagama requires
eight days of firing; a long time to carefully
avoid damaging the ware. On a visit to fellow potter
Kusakabe Masakazu in Miharu, Matsumiya
studied Kusakabe’s version of the bourry box
kiln in which ash drops from an overhead grate
in one chamber onto the side of the floor of a
second chamber. A few pieces in or near this
area developed the appearance Matsumiya
sought. The ware must be small to avoid
blocking the holes between the chambers.
Thus he decided to design a single-chamber
kiln in which low side stokeholes are
used to heat and maintain temperature
while three high stokeholes located in the
front are used to place wood on grates over
most of the pieces. Because the work gets
covered in the embers from above, top stoking
alone is insufficient to ensure watertight
vessels and to maintain the temperature to
melt the ash. So, after the kiln is brought to a
temperature of 2282°F (1250°C) by side stoking,
long pieces of wood are front stoked (he
continues to side stoke to maintain temperature).
The embers created from the front stoking above
fall onto the work.
Matsumiya has found that using four bundles of
wood creates the best results. A bundle is about 4 feet
(1.2 m) in diameter and 6 feet (1.8 m) long, made up of
Sake bottle, 15 cm (6 in.) in height, thrown stoneware
(a blend of local Kanayama clay and Shigaraki clay),
unglazed, wood fired, by Matsumiya Ryoji.
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The kiln door in the center front of the kiln is bricked up for firing. A square in the middle of the kiln door becomes
a top stokehole later in the firing (see diagram below). The before-and-after pictures above show the
ware stacked under removable brick hobs (left) and the bed of coals (right), produced by top stoking, which
covers the ware later in the firing.
angle iron arch supports
concrete wall for
added support
side stokehole
(one on each side)
top stokeholes
draft holes for top stoking
draft holes for side stoking
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The central row
of brick hobs are
removable to allow
for stacking ware
below the grate.
The top firebox
runs the entire
length of the
ware chamber.
The ware stacking
area is directly beneath
brick grates,
and becomes buried
in coals as the
firing progresses.
Top View
Side View
As the firing nears completion, Matsumiya adjusts the draft hole in the front of the Hai Kaburi kiln before
continuing to side stoke.
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¾-inch square (2×2 cm) wood scrap. As each bundle is added
gradually, the ash coals completely cover the ware. Then
they are allowed to burn down before the next bundle is
added. This ash-covering process takes about 24 hours. Top
and side stoking are complete when Matsumiya is satisfied
with the coverage of final ash. The graph below illustrates a
typical firing schedule. As a result, the ware develops melted
glaze at the upper surfaces, different colors (gray, brown,
black and some blushes), and a crusty finish below. He prefers
ash glaze melted on the top third to half of the ware,
leaving a rough, crusty and eroded appearance on the remaining
lower portion. Constructed of hardbrick, the kiln
takes four days to cool. The larger ware is soaked in hot
water when unloaded to prevent cracking. Surfaces of some
ware, such as sake bottles, are lightly sanded with fine sandpaper
to make them easier to use.
Matsumiya now bisque fires most pieces to minimize
breakage. The interior dimensions reflect practical considerations.
The lumber company scrap is just less than 6½ feet
(2 m) long and six hardbricks are 4½ feet (1.4 m) wide, allowing
for mortar.
The kiln produces consistent results, but Matsumiya
will continue to adjust the firing process to improve the
look he prefers.
For more information on Kusakabe Masakazu’s bourry box
kiln, see Japanese Wood-fired Ceramics, by Kusakabe and Marc
Lancet (kp books, 2005).
the author Lee Middleman is a full-time ceramics artist living in
the San Francisco Bay Area. He participates in wood firing in Japan,
Korea and China. His website is www.leemiddleman.com.
Firing Schedule
The kiln is fired with oil for the first 24 hours in order to
get the temperature up to about 450°C (850°F), after which
the kiln is side stoked for the remainder of the firing. Once
the temperature reaches 1250°C (2282°F ), top stoking
begins in order to bury the ware in embers from above.
Vase, 30 cm (12 in.) in height, thrown stoneware
(a blend of local Kanayama clay and Shigaraki
clay), unglazed, wood fired on its side with ash
drips, by Matsumiya Ryoji, Aomori, Japan.
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The Manabigama
For more than thirty years now, I have been building,
firing and maintaining various large wood
kilns. Almost all of them have been a design taken
directly from the chamber kilns used historically
around the world. My present kiln is fired seven times
a year for my personal work and also for group workshops.
The kiln is a 300-cubic-foot cross-draft, with
three chambers in the traditional noborigama style.
Two of the chambers are used for glaze work and one
is used for salt glazing.
I started using this kiln nine years ago for teaching
group workshop firings. I schedule three a year, which is
all I can manage given the labor and time involved. Each
year, the groups enjoy the experience and the work that
comes from it, but many ask for additional space in my
kiln at other times during the year, which is not possible
given my production schedule.
With new ideas in mind, I set out to build a very versatile
and efficient wood-firing kiln that could be used by students
who had interest in a complete hands-on experience, from the
preparation, loading, firing and unloading to the final cleanup
phase. I didn’t want to interfere with the successful larger
firings, in which students can get a large volume of wood-fired
pots without the in-depth hands-on experience. The new kiln
would allow me to cut down on the extensive labor, fuel and
overhead costs of my larger kiln.
I named the new kiln “Manabigama” at the suggestion of
my friend Phil Berneburg, former technical editor for CM. In
Japanese, mana means educational or learning, bi means a
thing of beauty, and gama means kiln. The Manabigama is a
traditional design with a few simple modifications. I see it as a
cross between an anagama and a groundhog-style kiln. Basically,
it is a cross-draft tube built into the side of a hill.
The overall interior dimensions are 24 inches in width, 7
feet in depth, 40 inches in height. Its firebox is in the front,
incorporated into the inside with a grate system, and extra air
intakes are built into the front and sides. This is done to provide
more secondary air intake to help burn green or wet fuel.
The firebox is plenty adequate being 2 feet wide, 2 feet deep
and 30 inches high from the floor to ware level. The chimney
has inside dimensions of 9 inches deep by 18 inches wide and
is 12 feet high. The shape is a long rectangle with two straight,
18-inch-tall side walls and a catenary arch built on top. This
creates ample headroom for ease of loading, as well as extra
height for stacking and tall pieces.
There is approximately 24 cubic feet of ware space, more
than enough for teaching purposes. The kiln door is in front,
only halfway down, and is bricked up including the stoke
by John Thies
hole. It can be loaded in two to three hours, fires evenly to
Cone 10–12 in eight hours tops, or if you choose, you can fire
two to three days depending on how much ash buildup you
like. The consumption of fuel is also minimal—less than half
a cord of wood.
All in all, the Manabigama is a very simple design to build.
It is capable of yielding wonderful ash-glazed pieces with a
minimum of labor, fuel and overhead costs. And it is a fantastic
wood-fired kiln for teaching without the tremendous strain
of a large three-chambered kiln.
Thanks to Phil Berneburg, who was instrumental in inspiring me to
build this kiln. For further information on Monocacy Pottery, see
www.monocacypottery.com.
John Thies stokes the 24-cubic-foot Manabigama.
Side view of the Manabigama during the cooling phase.
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Thoughts from a Manabigama
Guinea Pig
by Mea Rhee
I
had attended kiln workshops for several
years, and felt I was ready for more. I was
looking for a wood kiln that I could try to
fire by myself when John called and said,
“Come see my new kiln. I think you’re going to
like it.” Of course I volunteered to test fire it.
I had help and John was always nearby, but
for the first time I was able to manage the entire
process, which was my goal for this firing. The
kiln’s design is just right for a student at my
level. All of its processes are small, straightforward
and flexible. I love that there is no barrier
between the firebox and the pots, so the pots
receive as much effect from the fire as possible.
This is my goal aesthetically too.
I am already busy designing pots for my next
kiln load. I plan to gain as much understanding
as I can each time I fire it, and enjoy every
minute of it. This kiln is going to carry me to a
point in the future when I’m ready to build my
own. And when I get there, I’ll probably build
something very similar.
Bottle, 5 in. (13 cm) in height, stoneware with
natural fly ash glaze, wood fired to Cone 12 in
the Manabigama, by Mea Rhee, Silver Spring,
Maryland.
12’
4
4
4
Chimney
Side View of Kiln
Ware Chamber
The Manabigama kiln was constructed
with one layer of firebrick,
a 2-inch coating of mud and straw,
and steel buttressing, which is an
optional feature.
Top View of Kiln
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9”
4
4
Flue
4
4
4
4
4
4½”
60”
Chimney
4
Flue Exits
4½”w × 9“h
Ware Chamber
24”
4
Firebox
24”
4
4
Air Intakes
4
4
4
4
9”
4
4
40”
4
4
60”
4
4
25”
4
4
4
4
4
8”
l l l
4
Removable steel
grate bars
Ash Pit
4
24”
Fire Box
4
4
4
4
67”
4
4
4
Three removable
steel grate bars
1½–2” in diameter
Stoke
Hole
Air
Intake

Wood-fired Raku Kiln
by Nesrin During
Handbuilt vessel, approximately 6 inches in height, with ironspotted
raku glaze, reduced in sawdust, by Nesrin During.
Wood isn’t just for high firing. You can build a simple raku kiln
and fire your work with wood to get stunning results.
This simple, self-built raku kiln is made of stacked
bricks and sized to fit what I’m planning to fire.
Sometimes I start firing small objects, then add
another one or two rows of bricks for the bigger
objects. These kilns are built wherever I want them to
stand, taking into consideration the direction of the wind.
The day after I’ve finished firing, I put away the bricks, out
of sight under a roof or in a shed to keep them dry until
the next firing.
Kiln Construction
A typical kiln is built from about 50 insulating bricks
(IFBs), a square kiln shelf (size depending on what I want
to fire), a metal grill for a grate, a piece of sheet metal,
and some broken shelf pieces. It takes about 45 minutes
to build, and fires to about 1650°F in about 45 to 60
minutes for the first firing; thereafter, every load takes
15 to 20 minutes (one can see the glaze melting, the pots
shining in the flames, from the top of the kiln).
To begin, I level the surface with a layer of dirt; it will
also protect what is beneath (concrete, for example, can
crack with the heat). I look at the direction of the wind
Wood-fired raku vessel, approximately 6 inches in height,
handbuilt, with poured glazes.
and accordingly build the firemouth to receive the wind.
Depending on the size of the kiln shelf (it’s going to
diagonally span the walls), I lay two courses of bricks to
establish the back and side walls. Upon these the grate
is placed so that the ashes can fall through (figure 1). (My
iron grate was salvaged from a dump; one could also use
a kitchen oven grate, which would last a few firings).
Then another two rows of bricks are laid, and the kiln
shelf placed diagonally so that the walls support three
corners. A piece of sheet iron (also salvaged from the
dump, but you can also use a piece of angle-iron) across
the front of the kiln supports the fourth corner (figure 2).
Because some of the bricks in the following course
will stand on the kiln shelf, I have to raise the others to
the same height with pieces of broken shelves. After this
leveling course, a couple of rows are laid in a diminishing
circular pattern (figure 3). I also partially close the top
of the kiln with broken shelves, leaving a central hole to
function as a chimney.
Firing
I fire this kiln (alone or with the help of students) with
scrap wood. The wood should be dry and thinly split.
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Two courses of bricks are laid to establish
the back and side walls, then an iron
grate positioned on top.
4
The kiln fires to about 1650°F in 45 to
60 minutes, while pieces for the next
firing preheat on top.
1
I start with some newspaper and thinly split wood
(figure 4).
The fire is well fed in the beginning in order to get
the bricks to temperature, but after the first load is
done, I fire with less wood and rake the fallen ash from
underneath the grate to ensure the fire has enough oxygen
to burn well.
Because the bricks are so loosely stacked, I can create
new openings between bricks to manipulate the flames in
a certain direction, causing interesting effects on pots.
The pots intended to go into the next firing are placed
on top of the kiln to dry. When the glaze on the pots
inside the kiln is shiny and molten, I remove a few bricks
from one side of the top to facilitate taking the pots out
(figure 5); the pots are then placed in a metal bin containing
sawdust (figure 6).
The glaze is a simple: alkali-borate frit (70%) with
kaolin (30%). With additions of 0.5% to 3% iron oxide,
this gives very beautiful pinks and grays (pink to pome-
After another two courses of brick, a
sheet of iron across the firemouth supports
the corner of a kiln shelf.
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2
3
Some of the bricks in the following
course stand on the kiln shelf, so level
with pieces of broken kiln shelf.
When the glaze on the pots inside is molten, remove a few bricks from one side of
the chamber to facilitate removal of the pots for post-fire reduction.
5
6
granate red in oxidation, and gray to black in reduction).
Additions of 2% to 3% copper carbonate yield apple
green in oxidation and bordeaux red in reduction. Other
oxide combinations, such as iron and copper, or iron and
manganese, are also good.
The amount of crackle depends on the type of clay used
and the handling. After taking the piece out of the kiln,
if you keep it in the air for a minute or so before putting
it in the reduction container, you’re bound to get more
crazing, especially on a smooth surface. If the surface is
rough, you’re more likely to get iron oxide “bleeding,”
producing thousands of little dots and giving the piece a
rocklike appearance.
Building such a kiln requires few materials, and fuel for
firing is equally economical. Because it is a wood firing,
there is bound to be some oxidation and some reduction
at the same time. The resulting variation in surfaces gives
beauty and individuality to the work. Not every piece
comes out well, but some are really wonderful.

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