A (Very) Short Course in Raku - Making Pots

A Muddy Hand Workshop Manual By Denny Means

Raku is a method of firing pottery that began in Japan, 300 years ago. The name Raku comes from the Japanese ideograph, raku, and means enjoyment, contentment, and happiness. Raku firing as practiced in America is the result of work by Bernard Leach, and continued by Paul Soldner and others in the 1950’s. In Raku firing, we fire pots fast, then remove them from the kiln and do something with them. This yields stunning colors and brilliant metallic effects, with shading and color blends available in no other method of firing pottery. Raku work is valued for the unique colors and for the dramatic way in which it is fired.

Our goal in this firing is to learn and enjoy the process, and to come away with some great pots! We will learn a lot from the firing – some lessons can be applied the day of firing; some lessons applied to our future work. Raku firings are a social and collaborative event. We will work together to glaze and fire pots in the spirit of Raku that will give us “enjoyment and happiness.” Potter Robert Piepenburg states, “The raku process is a journey of cooperation and pleasure – an exploration of a different way.” Cooperative work of the group is one key to the success of the day. Sculptor Bob Lockhart says, “The generosity of spirit you bring to the event will have a lot to do with what you take away.” In addition to great pots, we want you to take away the story of how this work is made and fired.

In raku firing, we color pots by means of glaze and smoke. The pots are formed, dried, and then bisqued to a low temperature. Raku pottery is decorative only and not for food use.

Raku work is variable and can yield different results, even within the same firing. Many of our pots will have outstanding colors and beautiful random shadings created by the flames. Some pots will have a matt finish and mild color. Some pots will have flashes of metallic copper. A few pots may break in the firing. This process, and each pot, will help us in learning how to make better pots and how to fire them for good results.

Each firing is another step on our learning path, and improved results come as we learn more through experience. This reinforces the point of enjoying the process. We don’t seek to judge the experience only by the product - the finished pot. We will get some great pots, but we also want to focus on the process, the cooperative work, and the event. Part of the day’s product is the experience. So, keep it fun!

Denny Means will be your tour guide for the Raku workshop. Denny has studied Raku for several years and admits to a fascination with the direct application of smoke and flame to pottery. So, bring your pots, a sense of humor, and a willingness to experiment and we will learn a little more, together! This little manual cannot cover everything you need to know about Raku. We highly recommend additional reading from the books listed later in this digest. Please email me your comments or to add any important tips we should include in these pages.

Those who read these tips through will find a Bonus and the Luster Secret somewhere in these ramblings. Copyright 2005, Denny Means, All rights reserved. 2005 by Denny Means, Crooked Tree Studios

Revised 22 August 2005

Raku Firing

In Raku, we fire pots fast - about 40 minutes, or less. Your electric kiln would take 8 hours or more to do this. Most of my glazes are formulated to mature around 1870 degrees. Once the glaze reaches maturity, we open the kiln, and remove the pot with steel tongs. The glowing hot pot is put into a metal can. The can has a few sheets of newspaper in it, which instantly ignites from the heat of the pot. Flames flare up; the paper burns for a few seconds. The lid is placed on the can, smothering the flame. After 20 minutes, the can is opened. Being careful not to breathe the smoke & fumes from the can, we pull the still hot pot out, and then plunge it into a bucket of water!

Inside the metal can, the flame wants to burn; it pulls oxygen from the claybody and the glazes. Copper oxides become copper with the loss of oxygen. Smoke permeates the open pores of the clay. These changes yield the great colors of Raku. To stop the chemical changes in the glaze, we cool the pot in water. Later, we use scouring pads to clean residual tar, carbon, or fire debris from the pot.

The sudden radical temperature changes can be a real test for a well-made pot. Following are my tips to help you have successful pots at our raku firing. Like everything else in pottery, these tips are not the final answer, or the only answer. These tips are general guidelines for a pretty good Raku pot. As you learn more, let me know of points to add to these pages.

Bring up to 5 bisqued pots on the day of the firing. (Clay Alliance Workshop Participants see your announcement) Bisque to Cone 05, or what you are comfortable with, down to cone 08. Pots should be made of Raku Clay. We want Raku Clay used for everyone’s safety. At a public Raku firing, several pots from different potters will be in the kiln at any one time. If one pot blows up, it will almost certainly damage or ruin other potter's work. (Clay cost is about $8 to $11 a bag. I ask myself, is saving $8 so important that it is worth risking the ruination of a friend's pot?) Pots up to 14” high can be fired.

In general, there are two main types of raku clay stocked at local (Cincinnati) clay dealers. The Mud Pie Shop and Maxfield Ceramics both now stock Standard #295 Raku clay. This clay contains kyanite, which provides great strength, plus other very fine grog. The Standard #295 Raku clay is what I use; the texture is as smooth as regular stoneware, if not more so. It throws well. Maxfield's also carries a Columbus Clay product called "Raku Clay." This clay uses a coarse sand type grog and is not recomended for wheel throwing. It makes good slab-built items and tiles.

Leftover raku clay can often be treated and fired like a regular cone 6 stoneware. However, test your exact clay before using it on a treasured item at cone 6.

For Thrown Pots:

Wall thickness could be a bit on the thick side, rather than on the thin side. (Thin walls lose heat fast, thus certain raku glazes will not reduce well on them.)

Wall thickness of say, ¼ inch minimum. In general, thickness should not exceed 3/8 inch.

Keep wall thickness consistent all the way up. If the walls of the piece vary a whole lot, these sections heat and cool at different rates, and will also expand and contract at different rates. Differential expansion may cause cracks and breaking of your work.

Compress. Compress. Compress. Compression makes the clay stronger and more crack resistant. Compress the bottoms of your pot. Compress the top edge of the pot as it is thrown. Compress the rims. Avoid air bubbles. Deflate any air bubbles. Trapped hot air may explode in the kiln.

Handles, spouts, or appendages should be pressed into the base form and well joined. Score and slip. Execute the fundamentals. Where possible, paddle the joints.

Wide-bottomed forms can be a problem in raku; a greater tendency for differential expansion makes them more vulnerable to cracking. Forms up to say, 4 inches wide at the base should be no problem. Forms from 4 to 8 inches wide should be well compressed and of thickness consistent with the walls of the piece. Forms wider than 8 inches, including plates, become more crack prone. (Of course, there is always super glue.) Please discuss with Denny any plans for wide items, or items taller then say, 14.”

For Slab Work:

Roll the slab in multiple directions for strength. Compress the slab well. I use a large, canvas-covered wooden mallet to pound a ball of clay out to a thick flattened slab. Then roll in multiple directions to smooth out and develop final thickness.

Minimum slab thickness of 1/4 to 3/8 inches. (Too thin does not hold the heat we want.) Roll the slab larger than you need, then cut away the edges before forming your piece. Using only the center portion of a slab may help limit cracks at the edges.

Just before the final rolling, go around the slab edges and push in the edge with your fingers. Compress and stroke towards the middle of the slab to minimize edge cracking. Roll out finger marks, rolling towards the center.

Make sound joints – score and slip. Backup with a fillet of clay, everywhere possible. Lightly paddle the joined edges where possible. You know, the fundamentals – they work!

In making slab-built work, try to join only slabs of similar moisture content. Joining a fairly wet slab to a dry leatherhard, drier slab will likely yield cracking in Raku.

Place the assembled piece inside a plastic bag overnight to equalize moisture within the piece. Remove from bag and dry slowly, or partly covered, in order to develop maximum strength in the piece.

General Pot Making:

Consider how your red-hot piece will be picked up from the kiln, moved to a can, and put inside a flaming can by me. (I’m not that graceful – unkind folks liken it to a bear dance.)

Long, unsupported appendages can be broken in the rigors of moving the pot to the can, or cleaning.

When finishing raku pots, be careful if wiping with a damp sponge. If you do, it can wash away the fine clay particles and bring out a big grain of grog. At times, the big grain of grog or sand will make a gash mark in the piece as it is dragged across the piece. If the piece is still leather hard, the deep gash mark can be repaired with a bit of slip and magic water, or slip with a little vinegar. Alternatively, this could be the place to try a very coarse texture on you pot. Try filing a pot down with a Sureform file and leave it rough textured.

Write you name on your pot - this is a group firing.

Glazing:

You are welcome to use my glazes. Most of my glazes are designed to mature around 1850 – 1910 degrees, this is fairly high temperature for raku. Firing to a higher temperature gives improved color retention over time. Raku glazes may fade if placed in direct sunlight. Raku glazes are not food safe. My Raku glazes are lead free.

Glazes at Crooked Tree Studios: Harry Hearne’s White Crackle, Copper Matt, Dolphin Blue (semi-matt), Blue-Black Copper, Denny’s Mad Awabi – glossy copper to sometimes gold, Clear Crackle, and others as they are available. Application is by brushing.

We fire with a digital pyrometer for temperature control and semi-repeatable results. This tool lets us know what is going on inside the kiln and helps time the firing. We go by temperature and the finished look of the glaze at maturity. Cones are not used.

Pots need to be glazed and bone dry before firing in the kiln. Be on time and glaze your pot first thing. Pots bisqued low will absorb more water and need longer drying time.

DO NOT GLAZE THE INSIDE OF YOUR POT OR IT CANNOT BE FIRED. Glazing the inside of the pot on the day of firing puts a lot of water into the pot. The pot cannot dry out before firing. A wet pot may explode, damaging several other pots. Typically, the inside of a raku pot will be “smoke glazed” black. You can glaze the inside lip, down a ½” to 1” or so.

Remember, Black is a color available in raku. Unglazed areas turn black from smoke absorption. Black can be used to good effect on portions of a piece. Example: Painting the “stems” on with wax resist before glazing can indicate lines of grass or wheat.

Glaze results vary by thickness of application, firing temperature, reduction during firing, and postfiring reduction. (“Reduction” = denying oxygen to the pot & the glaze.)

White Crackle and Clear crackle glazes are applied relatively thick; say two brush coats. Tell Denny your pot has white crackle on it when it is fired. White Crackle pots are cooled in the air before putting them in the metal cans. Be ready to blow on the pot.

Copper matt glazes are applied on the thin side, say, two thin brushed coats.

Blue-Black Copper and Denny’s Mad Awabi are applied on the thick side; say two coats.

Dolphin Blue is applied in two thin coats. Note: Where Dolphin Blue crosses over top of White Crackle, it turns a dark cobalt blue. This can “spice up” a white crackle pot. (White Crackle on top of Dolphin Blue does not yield the same result.)

You may use your own raku glaze, or commercial raku glazes. However, you must tell me what temperature it matures at. Remember, to make a kiln load, we need 5 to 7 pots of the same glaze maturity temperature, so have someone else use the same glaze.

If you want to use a commercial glaze before the day of the firing, I recommend the Spectrum Brand Raku glazes. Fans of red enjoy Spectrum’s Raku Red. These glazes mature at much lower temperatures than my glazes. Typically 1650 to 1750 degrees. Key Point: Put a note with the glaze names/ temperature inside your pot. The alternative: don’t bother with such minor details; end up with a black cinder of overfired gunk. I’ve been there, with a gloomy charcoal pot. L

If you want the inside of your pot glazed; do it the days before the firing, using your own cone 05 glaze or a commercial glaze. Do not glaze more than 1” down inside the pot on firing day.

Need more choices? Your underglazes can be used. Days before the firing,

apply underglaze. On the day of the firing, apply 2 coats of my clear crackle over the underglaze. Result is a smoked version of the underglaze, with crackle.

Once glazing is complete, we will sort pots by glaze color and maturity temperature. Then place them on tables in the kiln area.

The Firing

At the firing, the gas kiln will heat the pots to temperature. To confirm glaze maturity, look for a smooth sheen on the wall of the pot in the kiln. One analogy I’ve read said that the look you want is “like a smooth sheen of water on a sheet of melting ice.” This does not apply to matt glazes, which will look, well, “matt,” and dry.

Once the kiln is opened, we will move the pots to the metal cans quickly. The copper glazes need to carry heat into the can for proper reduction. Reduction means “reducing the amount of oxygen” in the atmosphere around the piece. Placing the hot piece in the can with newspaper starts a fire. Putting the lid on the can denies oxygen to the fire. The fire wants to burn, so it pulls oxygen molecules from the glaze, and from the clay body. Particles of carbon – smoke are pulled into the clay body. If you begin with glazes containing a copper oxide, then remove oxygen molecules, what is left behind is copper.

Some people like the bright copper effects possible in Raku. It should be noted that, just like a new penny, bright copper may oxidize and get a patina over time. One way to slow or prevent this effect is to coat the piece with a sealer, such as Jasco Silicone Grout Sealer. Jasco is a product made for use in tile bathrooms. It does not seem to discolor the Raku piece. Other folks may enjoy subtle changes in raku glaze colors over time, as part of the ongoing raku process.

Pots with white crackle glaze are treated differently. To get the crackle effect, we will let the pot cool once it is removed from the kiln. Often, we will blow on the white crackle to cool it faster, which accelerates the glaze cracking. Some people will spray a mist of water on a white crackle pot to accelerate cracking, but this can also lead to cracks in the pot. Crackle glazes get cracks because the glaze cools fast and shrinks faster than the cooling pot. When the pot is put into the metal can, smoke is drawn into the claybody, which outlines the cracks with fine black lines. A fairly thick coat of glaze typically produces good crackle patterns.

Raku vessels are made from clay with an open body and water will wick through the walls of untreated pots. If you want a vase to hold water, coat the inside with Thompson’s Water Seal, or another silicone based wooden deck sealer – a tip from Harry Hearne, Raku artist and teacher.

Raku glazes are comparatively soft and may chip more easily than work that is fired higher. Raku pieces are not fully vitrified and may not be as strong as ware fired to cone six, or cone ten. However, even with these cautions, Raku work is prized for colors and effects that we can get with no other method of firing.

Bonus for those who have read this far: Consider making a small “medallion” or two. These pieces can be used in a necklace. Roll a well-compressed slab- not too thin, say, 3/8” thick. Carve or stamp a design in a section of the slab. Then cut out the design as a small tile or circle, about 1.5” to 1.25” diameter. Once it stiffens to leatherhard, drill a 1/16” dia. hole through the top part of the tile, ¼” down from the top. This hole is for your string to go through –if the hole should close up, you are making a refrigerator magnet. On the back of the leatherhard piece, scoop out a bit of clay to lighten it. We will glaze this pieces and fire them on a carrier rack that I’ve made. ( Pieces that are too thin do not seem to hold enough heat for good colors in reduction.)

The Luster Secret. Sometimes you want to add just a bit of glamour to a completed matt piece, or a medallion. Apply Hanovia brand “Brass” luster glaze to a detail area on the medallion. Expensive, at about $18 for a tenth of an ounce. This glaze is fired to cone 019, or 1283 degrees. Wearing a clear face shield, hold the medallion with pliers and heat the dry medallion with a propane torch. In minutes, the torch will heat this particular glaze enough to mature it to a brass color. Voila! Fast-fired luster! Once you get the color desired, immediately quench the piece in water. I learned to wear a face shield when a red-hot piece of a pendant blew off and hit me in the mouth.

A fat lip with a burn on top make a memorable lesson. Someone told me that this illustrates what Will Rogers called the three kinds of men. I suspect this was not meant as a compliment.

The “secret” of dressing for Raku: Get your authentic Raku Wear and LOOK HOT! See www.cafepress.com/fire_raku_pots or www.cafepress/potterypeople/

…and when people see that flaming bowl picture, you can say (modestly, of course) “Yeah, that’s the kind of pottery I fire.” They will know, you da’ bomb!

There is more, please read the safety section to follow.

At this point we have scratched the surface and given you several tips on making strong pots to survive the firing. For more information, I encourage you to read some of the books in the recommended reading list, and discuss things with other, more experienced potters in the workshop.

I add, don’t let all these tips and techniques worry you. Your pots will probably be fine.. Just make your work using sound fundamental techniques. We will cook ‘em and have a fine time!

Notice: These pages, and the information presented herein are copyrighted instruments of professional service. Do not copy or further distribute. Do not scan or store in electronic form. Reprints only with permission of the author. Copyright 2005 by Denny Means, Crooked Tree Studios

Raku Firing Safety

An important goal of the workshop is to work safely. The most important tool in safety is your thinking cap. Please bring yours.

Most people will have jobs to do. (A list of jobs is below.) Volunteer for the job that you are comfortable doing – handling hot pots with tongs is not a requirement. We will orchestrate a “dance for two” to move pots from the kiln to the cans. Don’t inject unexpected moves into the dance by doing something you were not assigned.

Dress appropriately: wear sturdy shoes and long pants. Clothing should be made of cotton, for its resistance to flame. Nylon jackets, polyester pants, etc. should not be worn to the firing. Don’t wear sandals or flip-flops. If it is cool, wear a cotton sweatshirt over warm sweaters, etc. Don’t wear a coat with a polyester or nylon outer covering as these could "melt" with you in it.

When lifting the lid of a metal trash can always be cautious! Unburned gases may ignite on contact with air making an unexpected flare of flame. Wear gloves to handle the can lids. When opening a cooling can, avoid breathing the smoke and fumes from inside the can. This may be the place to wear your respirator.

Metal can lids can get a coating of black tar on the edge. This tar may permanently stain clothing. Don’t brush a can lid against your pants leg, etc.

Those working at the kiln or the cans will wear gloves. Please keep gloves DRY. Wet gloves loose their insulating value. If your glove gets wet, dry it on the top of the kiln, and keep an eye on it.

Please note that there are several potentially hazardous chemicals being used in glazing and raku firing. We advise you to review the manufacturer’s Material Safety Data Sheets, and to wear personal protective gear that you bring with you. This activity has known hazards and you should not participate if you cannot do so at your own risk.

Do not eat or drink the glazes or glaze materials. Raku ware is not food safe.

Participants concerned about irritable fumes may wish to bring their own respirators.

Raku firing is done at your own risk. As partial payment for this workshop, users and participants agree to hold harmless and indemnify the instructor, the authors and distributors of this material, and the Clay Alliance. Participation in the workshop signifies that you agree to these terms.

Notice: These pages, and the information presented herein are copyrighted instruments of professional service. Do not copy or further distribute. Do not scan or store in electronic form. Reprints only with permission of the author.

The Job List

Raku firings are cooperative and participatory. No, everyone will not have to belly up to a hot kiln – that is voluntary. Just be prepared to pitch in and help with the chores. The work is shared, and pretty light duty. Duties include:

Tong Team (handlers of hot pots, Denny will lead this team) Wear insulated gloves, provided.

Lid Team (People who put the lids on flaming trash cans.) Wear insulated gloves.

Can Can Team (People who prepare the cans with fresh paper, empty ashes, etc. High kicks are optional, though encouraged.) May want to bring and wear uninsulated work gloves.

Cleaning Crew (People who clean carbon off the pots after they are cooled.)

This breakdown sounds more organized than it really works; loose organization is about the best we do, typically.

Directions to Mary & Denny Means’ Crooked Tree Pottery, in Mason, Ohio

From East Side of Cincinnati:

From I-71, exit at King's Mills Rd. (exit no. 25).

Go West (away from King’s Island) one mile.

Right onto St. Rt. 741, go approx. 2 miles. At a stop light turn

Left onto Bethany Road, go to next intersection.

Right onto Mason-Montgomery Rd. go approx. 1.3 mi. Take second

Left onto Brewer Rd. go approx. 1/2 mi. Take second

Left onto Club Commons Dr. about two blocks to dead end into Bentwood.

Left onto Bentwood Dr. to no. 5254. A stone house, the studio entry is at the rear, lower level.

For those using www.Mapquest.com, the complete address is 5254 Bentwood Dr., Mason, OH 45040 Cell Phone: 513-382-2352

From the West:

Exit I-75 at Tylersville Rd. (exit no. 22).

Go EAST approx. one mile on Tylersville to a stoplight at Butler Warren Rd.

Left (North) on Butler Warren Road (a county-line rd.), approx. 3 miles to Brewer Rd.

Right onto Brewer Rd. (This intersection has “Miliken Rd.” sign on the left(west) side and Brewer Rd. sign on the right side of Butler-Warren. The counties could not keep it simple.) So, now you’re going east on Brewer Rd. about 1.2 miles to the second right turn.

Right onto Club Commons Dr., go two blocks to dead end into Bentwood Dr.

Left onto Bentwood Dr. follow to the end cul-de-sac. We are the stone house on the left.

The studio entry is at the rear, lower level.

For those using Mapquest, the complete address is 5254 Bentwood Dr., Mason, OH 45040 Phone: 513-382-2352

aCLAYÞFIREëARThRAKUõ

Acknowledgements and Recommended Reading

All of us working in clay know that we owe a large debt to those who taught us and helped us along the path. I say thanks to the artist-instructors who taught me:

Harry Hearne, Trina Feldhake, David MacDonald, Patsy Cox, Mark Shapiro, Pete Pinnell, Hayne Bayliss, Matt Long, and Bob Lockhart. Further thanks to many individual potters and artists I’ve worked with who have been generous in sharing their knowledge, support, and encouragement.

Another truth in ceramics is that there is always more to learn. The following books are very high on my recommended reading list. I am certain there are other good books on ceramics; here I have listed the books I own, which I believe will make an impact on your work.

Raku Pottery by Robert Piepenburg

A book that you will keep and reread over time. One of the two must-read books.

Raku – A Practical Approach by Steven Branfman

The essential book for Raku Potters. A constant reference and guide. The second of the two must-read books.

Clay – A Studio Handbook by Vince Pitelka

The essential studio handbook for many topics. Pitelka’s instructions get to the heart of making and firing ceramics. Read and absorb this text to help move your work to a higher level. The section on centering fixed a lot of problems for me!

http://www.wardburner.com/claytimes.cfm Not a book, but a website. Marc Ward’s columns in Clay Times Magazine are a gold mine of information for those interested in building a kiln and understanding kiln firing. Marc’s burner systems and his tandem propane tank connector are excellent products. Using these products makes raku firing safer and more enjoyable. Plus, if you have a question, Marc will talk to you on the phone and do what he can to help!

Pottery – A Life, A Lifetime by Mel Jacobson This dean of American potters writes his story.

Raku - second edition – by Tim Andrews. A good collection of Raku in the gallery.

Denny Means

Ceramic Artist and Instructor – Information

Denny Means uses earth elements – clay, wood, metal, and fire, to make unique sculpture and vessels. Collectors use his work as an accent or centerpiece of their garden and home décor. Denny is a full-time sculptor and ceramic artist, working from his studio in Mason and at Pendleton Art Center, #512. Mr. Means worked some years in steel construction and he finds his prior experience a great asset. “It’s all about taking a thought from imagination and making it into reality,” states Denny.

His ceramic pieces are often colorful and much of his work is fired using the dramatic Raku firing process. In Raku firing, one opens the kiln at 2,000 degrees and takes the piece out while it is glowing hot. The piece is placed in a metal chamber where sawdust ignites, flames shoot up, a lid is placed over the container. Fire and oxygen combine to make brilliant metallic flashes on the glazed ceramic work. “Raku remains a fascination for me, working up close with the fire demands commitment of the artist and well-made work. Fire can be a harsh master, a great collaborator, and remains the test required of no other art form,” says Denny.

Denny has formally studied sculpture and ceramics intensively for many years. His studies include master’s level classes in ceramics at Miami University and at Cincinnati’s Throwing Clay Pottery, a teaching studio. Denny studied Raku firing over two years at the John C. Campbell Folk School. His extensive study paid off this spring with the award of a fellowship as a Studio Assistant at Arrowmont School of Art and Craft. This fellowship allowed Denny to spend four weeks in Gatlinburg doing studio work coupled with coursework in sculpture and ceramics. Denny was employed by Arrowmont and lived and worked with other professional artists and instructors at the school. “Arrowmont is a place with abundant resources for art work. The school becomes a wonderful creative engine, powered by the energy of the artists and students living there,” says Denny. Mr. Means previously studied architecture at Georgia Tech and holds a bachelor’s degree from Wilmington College.

Denny’s focus is on creating sculptural wall pieces, coupled with incorporating other materials into the work, such as glass, copper, and steel. He continues to explore surface decoration techniques on vessel forms by using metal and glass to accentuate the work.

Mr. Means’ work is sold through juried art shows and galleries in the region. For more information and a schedule of appearances, see the web site at http://home.earthlink.net/~crookedtreepots/

aCLAYÞFIREëARThRAKUõ

Exhibit Dates: Pendleton Art Center each Final Friday, the last Friday of each month from 6:00 to 9 p.m. See new work by Denny Means and 100 other artists! Join us in Studio 512 for Denny's Ceramics, plus Glass work by Joe Drury.

Part of Final Friday Gallery Walk in the downtown Arts District, in Cincinnati.