PotteryMaking Illustrated • July/August 2007 31

I began raku fi ring at my local community col-lege using a gutted electric kiln. Later, I put my own kiln together using a metal trash can lined with Kaowool™ Cerablanket®, outfi t-

ted with a weed burner and fueled with propane from a barbecue tank. This design was fairly inex-pensive, simple to construct, and easy to transport and set up. But, good as it was, this kiln had a several drawbacks.

The time arrived to build a new raku kiln, so my engineer-potter friend, Robin Smith, and I went to work. Our fi rst task was to list what we wanted in the kiln, then we pulled together the best design elements

we’d seen in other kilns over the years and made up a list of requirements. The kiln needed to be:

• Low-cost, sturdy, lightweight, effi cient and safe• Made of readily found materials• Easy to construct using ordinary tools• Capable of handling a pot 15 inches high• Easy to access when removing pots• Safe to look inside during fi ring• Portable and easy to set up

Kiln ConstructionFor a 19-inch diameter kiln, cut 64 inches of fenc-

ing material from the roll. This allows for a 4-inch

Raku LiteBuilding a Portable Fiber Raku Kiln

by Daryl Baird

32 PotteryMaking Illustrated • July/August 2007

overlap (figure 1). Roll and shape the cylinder, check the diameter, and then use J-clip pliers to install J-clips down the length of the frame (figure 2). Twisted wires also work, but they bend the ends inward.

Carefully flatten the remaining fencing for the top, and trim it to a 20-inch square. Center the piece on top of the kiln, mark lines at a 45° angle just outside the edge of the kiln frame on each corner (figure 3).

Bend the corners to make the lid’s “feet.” These feet elevate the inside of the lid and protect it from damage when setting the lid on the ground (figure 4).

To provide a nice view of the kiln’s interior, install the 6×6 Pyrex window on the overlap six inches down from the top of the frame (figure 5).

Stand the kiln frame on the floor and loosely fit the fiber blanket inside of it. Mark the excess material to be trimmed leaving less than an inch of overlap. Note: The fencing and fiber are both 24 inches wide. If the fiber

What You Will Need

Notes1. We used a weed burner for this kiln, but a commercial raku burner equipped with a regulator is best. The burner requires an adjustable valve.2. Any fairly new propane tank serves the purpose. The small, BBQ-size tanks for out-door grills tend to freeze up as they empty, so consider a larger tank or several tanks connected with a manifold.3. Farm fencing (not chicken wire) is available at farm supply stores and home centers. It’s easy to cut with a good, sharp pair of wire cutters.4. J-clips and J-clip pliers are great for join-ing the ends of the farm fencing. Trouble is, you have to buy more than you need for just one kiln and the J-clip pliers are almost es-

sential in order to use the clips. As an option you can join the farm fencing with short lengths of light-gauge wire. 5. Kaowool Cerablanket is available in 1- and 2-inch thicknesses, but the 1-inch is fine for this kiln. Purchase from a ceramic supply store.6. Insulating fire bricks (ISB, soft bricks) are available at ceramic supply stores. Hard bricks are not suitable for this application. 7. High-temp, 16-gauge wire is one of the most expensive components of this kiln. Check your local ceramics supply store.8. This is ordinary steel wire that’s easy to bend and twist. It’s used to hold the Pyrex glass window in place. Some ceramic sup-ply stores stock an item called “stem wire,”

which is used in glass ornaments, etc.9. For fired buttons, use cone 6-10 stoneware clay, roll it to ¼-inch thick, and cut 3-inch squares. When leather hard, drill two C\,-inch holes a half inch apart. Use a damp sponge to smooth the edges of the holes on both sides. Use 24 buttons for the kiln frame, twelve for the lid and keep four spares. Make two half-size buttons but with the same hole placement. One goes under the burner port, and the other is a spare.10. Purchase the Pyrex glass window from a local glass supplier/installer. We bought three for about nine dollars.

Tool List• Medium- to heavy-weight leather gloves• Dust mask• Goggles or safety glasses• Wire cutters• Channel lock pliers• Needle nose pliers• Hack saw• 18- or 24-inch carpenter’s square• Spirit (bubble) level• Yardstick• Permanent marker (medium point)• Retractable-blade cutter and extra blades• ¼- and ½-inch round files

Materials ListBurner, hose and fittings [see note 1]Propane tank [see note 2]7 feet of 24-inch wide farm fencing with 1×2-inch openings [see note 3]8 J-clips (require J-clip pliers) [see note 4]7 feet of 24-inch-wide Kaowool Cerablanket (1-inch thick) [see note 5]13 K24 insulating fire bricks [see note 6]28 feet of 16-gauge high-temperature nickel-chrome wire [see note 7] 2 feet of 24- or 26-gauge steel wire [see note 8]40 fired clay “buttons” made from 10-12 lbs. of stoneware clay [see note 9] Z\,×6×6-inch Pyrex glass [see note 10]3 6-inch kiln posts15-inch kiln shelf (1x15x15)

is a little longer than the fencing, do not trim it. With repeated firings, the fiber will likely settle down for a

better fit. Lift the fiber out and lay it on a table, and cut it to length us-ing a sharp knife and the carpenter’s square. With the Pyrex window in the 6 o’clock position, reinstall the fiber in the frame with the seam at 3 o’clock. Cut a piece of wire that’s

3–4 inches long. Bend it into a U-shape (figure 6a) and push it through the fiber until it’s snug against it (figure 6b) and the wire tips protrude through the kiln frame. Hold the button in place with one hand and trim the tips so they protrude only ¼ inch past the frame. Back the wire out and measure its new length, then cut the remaining wires to length.

Put four buttons on one side of the seam, locating the first one an inch from the top and an inch in from the seam. Push the wires through and use the needle nose pliers to bend each tip into a tiny hook that attaches to the kiln frame. Install two buttons in the 12 o’clock

CauTioN Wear gloves and dust mask

while handling ceramic fiber.

PotteryMaking Illustrated • July/August 2007 33

position—one an inch from the top and the other 8 inches below. At the 9 o’clock position, insert four more buttons. At the 6 o’clock position, place a button an inch from the top, then place one so that its bottom edge is located just above the view-ing window (fi gure 7).

Push a wire into the blanket at each corner of the viewing glass and use the pen to mark where the wire comes through. Draw straight lines to connect the four marks and you will know where to place the but-ton. Later these marks will help you know where to cut out the fi ber to reveal the window. The third button in this column goes an inch or two below the window and the last but-ton just about an inch off the bot-tom. Place a button on either side of the blanket area covering the win-dow. Return to the 3 o’clock posi-tion and put in four more buttons down the other side of the seam. For the burner port, cut a 4-inch wide by 5-inch high hole on the side op-posite the viewing window. Secure the fi ber with a button on each side of the port. Use a half-height button to secure the fi ber under the burner port (fi gure 8).

Before lining the lid, remove the eight center-most rectangles with wire cutters to make a 4×4-inch fl ue opening. Cut the remaining fi ber piece down to 20×20 inches, then press it into the lid frame and trim the excess. Do not cover the upturned corners of the lid frame. Use twelve buttons on the lid, with eight around the perimeter and one on each side of the fl ue opening (fi gure 9).

Building a Kiln CartThis kiln can be placed on a base

of insulating fi re bricks (ISBs), lo-cated on top of a concrete slab or concrete blocks. We wanted porta-bility so Robin designed and con-structed a simple cart. This cart makes it easy to move the kiln out of the way, even while it’s still very hot. Building the cart requires ba-sic skill with a metal-cutting saw, stick welder, angle grinder and welding clamps.

1

2

3

4

5

6a

6b

7

8

9

34 PotteryMaking Illustrated • July/August 2007

ID Description Material Qtya Frame ¹⁄8×1¼×22¾ inch angle iron 4b Centerline Brace ¹⁄8×1¼×20¼ inch angle iron 1c Back Leg ¹⁄8×1¼×6 inch angle iron 2d Front Leg ¹⁄8×1¼×6 inch angle iron 1e Gusset ¹⁄8×1¼×1¼ inch angle iron 2f Leg Brace ½×6½-inch-long round stock 1g Nut ½ inch diameter 2h Leveler ½×9-inch threaded rod 1j Axle Rod ½× 26¾-inch threaded rod 1k Flat Washer ½ inch flat 2l Nut ½ inch 2m Carriage Bolt ¼×1¼ inch 2n Wheels 7 inch diameter 2o Exp. Metal Mesh 22³⁄8×22³⁄8 inch 1p K23 Softbrick 4½×4½×9 inch 13q Mount Wire 9 ga.×31 inch 1r Mount Trough ¹⁄8×1×36 inch aluminum angle 1s Weed Burner or Raku Burner 1t Squeeze Clamp 1u Quick Link 1v Pull Chain 1

ConstructionCut four pieces of angle iron (a) to the same length

for the ISB frame. Cut 45° angles on the ends, weld them from the outside, and smooth the welds with an angle grinder.

Cut the center brace (b) to length and weld it into place, then weld a gusset (e) over each of the front cor-ners to complete the frame.

Weld the two back legs (c) and the front leg (d) into place. The front leg needs a brace (f) to give it strength. It’s welded on a diagonal from the bottom of the leg up to the center brace. Thread the two nuts (g) onto the leveler rod (h), adjust the nuts to line up with the brace and the leg, and then weld the nuts into place.

Weld the axle (j) approximately ½ inch up from the bottom of each back leg. Add a washer (k) to each end of the axle, slide on the wheels, then use the nuts (l) to hold them in place.

Two carriage bolts (m), with the heads protruding ½ inch from opposite sides of the frame, are welded on the back of the frame. The burner mount wire (q) will be anchored to these.

Lay the expanded metal mesh (o) into the frame and tack-weld it into place. The bricks must lay per-fectly flat in the tray. Smooth out raised areas with

an angle grinder. Set bricks into the frame and set the kiln in place.

Burner MountWe used a weed burner for our kiln and devised a

method to attach it. (Devise another system for the type of burner you choose.) Now for the trickiest part of the whole cart: the burner mount wire (q) and the burner mount trough (r). File a notch in one end of the trough to fit over the axle. We clamped the trough in a vise and used a ½-inch round file to cut this. Note: The notch you cut should be deep enough to hold the trough on the axle, yet open enough that the trough can be removed easily.

The trough had to be bent so that it would hold the burner horizontally in front of the burner port. We put the trough’s notch back on the axle and then looked at the trough from the side to judge the height and angle of the bend. After marking the location of the bend, we put the trough back in the vise and made the initial bend. After a few trials we had it where we wanted it.

The burner mount wire (b) is 31 inches long. We marked the midpoint at 15½ inches and made a soft bend, a slight bend 2 inches in from each end, then, us-ing needle nose pliers, formed hooks on the ends. Take your time here. The hooks have to be open enough to fit easily over the carriage bolts (m).

Hook the burner mount wire over the carriage bolts and let the mount wire rest on the floor. Next, put the notched end of the burner trough on the center of the axle, and then, while holding the trough horizontally, the mount wire was lifted until it touched the bottom of the trough. That contact point was marked so a notch, ½ inch deep, could be cut using a small round file. With the mount wire in this notch, the trough is held in place.

The burner was laid in the trough, positioned so the opening was just outside the burner port and clamped into place. With that, the burner hose was connected to the tank, we used soapy water around the connections to check for any leaks and, at last, we were ready for raku.

using the KilnBefore using the kiln, level it by adjusting the thread-

ed leveler rod (h). After the first firing, we wired a cou-ple of metal handles to each side of the kiln so it would be easy to move. We bought inexpensive gate handles and held them in place with the light-gauge wire. We also realized that it would be nice to be able to move the kiln out of the way while the kiln was still very hot so we attached a 4-foot pull chain (u) using a couple of ³⁄16 inch quick links (v). Place three 6-inch kiln posts in a triangular layout to support the kiln shelf. Locate one post directly opposite the burner at the back and widely space the other two on either side of the burner. •

Daryl Baird lives in Sagle, ID. He is the author of The Extruder Book published by The American Ceramic Society. For questions or comments, you can reach Daryl at idahobaird@nctv.com

PotteryMaking Illustrated • May/June 2007 31

For years, I wedged clay on a canvas-covered piece of plywood placed on top of my slab- roller table. While this system worked pretty well, what I really wanted was a heavy-duty

bench capable of handling all of my wedging needs. The criteria I came up with were simple and essential. The table had to be:

Very sturdy and stable—no wobbleSpacious enough for two people to use at the same timeSimple construction from common materials requiring only basic tools and limited knowledge of woodworkingEquipped with a shelf for clay storageEasily disassembled, transported and reassembled

l

l

l

l

l

Draft a sketch with the measurements for the table designed to fit your criteria. Nothing fancy.

2 1×4×8-ft. boards (pine, cedar, etc.)1 C\v”×48”×48” plywood, particle board or OSB5 2×6×8-ft. (pine, cedar, etc.)2 Screw eyes1 C\zn”×5Z\x” turnbuckle1 S-hook1 36” Stainless steel picture hanging wire Deck screws (1B\,” and 3”)

2 Sawhorses7-in. circular sawElectric drillB\cx-in. drill bitZ\zn-in. drill bit for pilot holesScrewdriver bit for the drillCorner clamp (optional)

Shopping List Tools Needed

CAUTION: This project requires power tools. Read and follow all safety information provided with these tools.

Carpenter’s squareMeasuring tapeWire cutterPliers

PotteryMaking Illustrated • May/June 2007 31

2×6s

Shelf

(this height should be equal to the height of the middle of

your hip)

Slab 24×36”

36”

A sturdy And stAble wedging bench

32 PotteryMaking Illustrated • May/June 2007

Construct the Slab FrameBegin the wedging table by building a 24×36-inch

box to hold the plaster wedging surface using 1×4s for the frame. (Note: Lumber measurements are pro-vided in “nominal” dimensions, meaning a 1×4 actu-ally measures 3/4×3H and a 2×6 is actually 1H×5H. The nominal dimension is the actual size of the wood as it is cut from the log before it is milled and dried.) Cut two boards 36 inches long and two boards 22H inches long. Assemble the frame with the #8×1L inch deck screws. A corner clamp helps a lot. Tip: To avoid splitting the wood, pre-drill ¹/₁₆-inch pilot holes before inserting the screws.

Use a piece of ¾-inch thick particle board or ex-terior plywood for the bottom. Place the assembled frame on it and mark around the outside of the frame. If you place the frame on a corner of the sheet, you’ll only need to mark two sides. Use a circular saw to cut out the bottom to exactly the same dimensions as the frame, making sure the corner angles are all 90°. At-tach the bottom to the frame using #8×1L inch deck screws every 6 inches or so. If you use particle board, seal the interior with exterior paint. If you used exte-rior plywood, there is no need to coat the interior, so you can just set the frame aside.

Make the LegsA wedging table should be at a comfortable height,

and you should customize the height by cutting the legs to suit you. In gen-eral, a wedging table that comes up to the middle of your hip will be com-fortable. A table that is too tall makes it impos-sible to maximize your upper body strength, and one that is too low puts excessive strain on your joints as you bend your hands backwards. This plan assumes a 36-inch high bench, so you’ll need

to adjust the measurements accordingly. Adjusting the height only affects the length of the four inner legs—all other measurements remain the same. Refer to the cut-ting pattern for cutting the boards and follow these guidelines:

Cut three legs to the height you need for your table, and one leg that is 48 inches long. The long leg will support the cutting wire.For the four inside legs that support the plaster frame, measure the legs and subtract the thickness of the frame.The remaining 2×6 is used for leg braces and cross braces. Cut four leg braces that are 24 inches long. These are as long as the plaster frame is wide. The cross braces are cut later to their final length so set the remaining 2×6s aside.Assemble the four legs by placing one of the shorter

boards on top of one of the longer boards. The bottoms should be flush. Use three #12×3-inch deck screws to assemble each leg. Clamp the boards together and drill pilot holes.

Attach the 24-inch leg braces to the legs. The bot-tom leg brace is attached approximately 5 inches from the bottom of the leg and the top leg brace needs to be flush with the tops of the shorter part of the leg. Use a carpenter’s square to ensure 90° angles. Use at least three #12×3-inch screws for each connection.

Assemble the Bench

Clamp the plaster frame to the legs and adjust them as needed to make sure they are perpendicular and square. Measure the distance between the two upper leg braces (this should be about 33 inches). Cut the two middle leg braces to the exact length needed. Make sure you measure twice and cut once! The cross braces, need to line up with the tops of the leg braces so get a helper since this is difficult to do by yourself. Tip: Using #12×3-inch deck screws, sink the screws from the out-side of the leg braces until they just penetrate the inside. Once the cross brace is in place, it’s a simple matter to drill them in the rest of the way.

1.

2.

3.

3 Connect cross braces and check for squareness before attaching them to the legs.

1 The completed plaster frame with the bottom attached.

2 Four assembled legs.

PotteryMaking Illustrated • May/June 2007 33

Use #12×2-G inch screws to secure the plaster frame to the bench frame. Drill these in from the outside be-cause if you ever want to disassemble the table, you’ll just need to remove these four screws.

Cut the lower shelf. This shelf should be cut narrow-er than the full depth of the bench so you won’t bang your shins into it while wedging. Attach with screws or nails and paint the shelf if desired.

4 Cut the cross braces to length and attach them to the leg assemblies.

5 Attach the plaster frame from the outside in case you want to disassemble the table in the future.

6 The lower shelf is cut to fit once the bench is assembled. The shelf should be set back a few

inches so you won’t hit your legs as you wedge.

Estimate Plaster and WaterMeasure the inside dimension of the plaster frame and

divide by 1728 to get the number of cubic feet. For ev-ery cubic foot you’ll need 62 pounds of plaster and 44 pounds of water (21 quarts). For example, if the inside dimension is 3H×22H×34H, that’s 2717 cubic inches or about 1.6 cubic feet (2717 divided by 1728). You’ll need 99.2 pounds of plaster (62×1.6) and 70.2 pounds of wa-ter (44×1.6) (or 8.4 gallons). That’s about one bag of plaster and 8.5 gallons of water.

Mix and Pour the PlasterNote: By the time the wedging bench is finished, it

can weigh about 200 pounds, so move the frame into place before you pour the plaster. Also, shim the legs as needed to make sure the table is perfectly level. Tip: Wrap plastic around the frame to keep plaster off the wood (something I discovered after I made my table).

A good plaster to use is USG Pottery Plaster #1 (or equivalent) available from most ceramic suppliers. While a few higher grades of plaster are available, they are more expensive and more suitable for making molds and castings. Gather up all the tools you need (buckets, scale, mixer, etc.) and place a plastic drop cloth down in front of the wedging table. Mix the fresh plaster in batches using tap water and clean containers, always adding plaster to the water.

For a table this size, mix the plaster in four batches so it is manageable. Measure out ¼ of the plaster and ¼ of the water into two separate containers. Mark the containers so you will be able to measure subsequent batches faster. After scooping the plaster into the buck-et of water, allow it to slake for a minute, then use a drill with a mixer and blend thoroughly but quickly. Pour the plaster into the frame and use a spatula to remove all of the plaster from the bucket as quickly as possible.

Repeat this process for the next three batches work-ing quickly. The last batch will bring the plaster to the rim. Tip: Anytime you’re pouring plaster, it helps to

6a You can add an optional shelf to the side of the table. I used a piece of scrap and two shelf brack-

ets, then cut a notch on each end for the legs. The corners were rounded to prevent injuries.

34 PotteryMaking Illustrated • May/June 2007

have some empty forms of various sizes ready to be cast using leftover plaster. To help the plaster settle, and to work the air bubbles from it, use a rubber mallet to tap around the sides of the frame for several minutes. At this stage, the plaster is setting up but the surface is still quite wet.

Finally, if your plaster is above the frame, use a piece of 1×4×36-inch wood as a squeegee and pull it across the surface from back to front. The excess plaster should be allowed to run off onto the plastic sheeting. With a sponge at the ready, clean up the front of the bench (if it wasn’t protected with plastic) and wash up

7 After measuring out ¼ of water and plaster, mark buckets so you can mix remaining batches quickly.

8 Add plaster to water and allow to slake (soak) for about a minute, then mix with a power mixer.

9 Pour the plaster into the frame and use a spatula to get all the plaster out of the bucket. Work

quickly and repeat three more times.

the bucket and tools. Dispose of all waste in a trash can and never allow plaster to go down a drain.

Add the Cutting WireDrill a small hole 1 inch below the top of the long

bench leg. Insert an eye screw in this hole and turn it all the way in until it is horizontal. Install the other eye screw in the top of the shorter bench leg on the same side. Use an S-hook to attach the turnbuckle to the up-per eye screw. Turn the eyes of the turnbuckle until they are almost all the way out, then loop the wire through the lower eye of the turnbuckle and wrap it around sev-eral times to hold it securely. Run the other end of the wire through the lower eye screw, draw out the slack and secure it the same way. With the wire cutter, trim off the excess wire. Twist the turnbuckle until the wire is taut.•

Daryl Baird resides in Sagle, ID. He is the author of The Extruder Book, published by The American Ceramic Society. He may be contacted by email at idahobaird@nctv.com

12 Attach screw eyes, a turnbuckle and a wire to the frame.

10 After table is filled, tap sides with a rubber mallet for a few minutes to work air bubbles to the top.

11 Use a board and scrape off the excess plaster working from the back to the front.