Firing techniques
Raku firing, and how to actually be good at it.
Take a pot to nearly two thousand degrees, open the kiln, and pull it out glowing. Drop it into a can of burning paper and shut the lid. Twenty minutes later you find out what you made. This is the whole process, the reasons behind every step, and video of the best people on the internet doing it.
Take a pot to nearly two thousand degrees, open the kiln, and pull it out glowing. Drop it into a can of burning paper and shut the lid. Twenty minutes later you find out what you made. This is what you need to know to do it, and nothing else.
Everything on this page
The whole idea
Raku, in about a minute.
This is not our workshop page.
We run raku workshops every couple of months. Watch the studio calendar and the next one will appear on it. If you are coming to ours, the rules and the certification are on the raku safety and certification page.
Fire a bisqued, glazed pot to a low temperature, around 1800 degrees rather than the 2200 a stoneware kiln reaches. Open the kiln while it is still glowing and pull the pot out. Drop it into a metal can full of paper and shavings, which catches fire instantly, and slam the lid on.
The fire burns all the oxygen inside the can in seconds, then starts pulling oxygen back out of anything else it can find, which includes the metal oxides in your glaze. That is where the reds and golds and the black crackle come from.
One fact explains every rule below. Your pot goes from near 2000 degrees to open air in about four seconds. Nothing else in ceramics does that to a piece of clay. Everything about how you build it, what you build it from, and how you handle it exists because of those four seconds.
And one more. The crackle is not in the glaze. It is a fault line with soot in it.
There are other ways to raku: naked raku, horsehair, copper matte, obvara, saggar. The Comprehensive Version covers all five with video, along with the history, the chemistry and the finishing.
How To Make Raku Pottery - A Step-by-Step Beginner Guide
Pottery Crafters
The clearest single overview on YouTube. He builds the pot, glazes it, fires it and reduces it, and he narrates what he is looking for at every stage rather than just showing you the fire. Watch it on YouTube.
Before we start
Why this page reads and watches at the same time.
This is not our workshop page.
We run raku workshops every couple of months, and this page is not one of them. It is the craft itself, taught the way we would teach it to anybody. If you want to come to ours, watch the studio calendar and you will see the next one appear on it.
Video is unbeatable for the parts of raku you have to see. How fast the tongs move. What a glaze looks like at temperature, when it stops being dry and goes wet and glassy. How high the flames come up out of a can the second a glowing pot lands in the paper. No amount of writing gets you there.
Video is terrible for the parts you have to remember. You cannot scan it. You cannot find the one line you needed twenty seconds ago. You cannot hold it up in a gloved hand while somebody is shouting at you and the kiln is open. And there is decent evidence that reading something and then watching somebody do it sticks harder than either one on its own, because the words give you a shape to hang the pictures on.
So this page does both, in that order, every time. Each section teaches in writing first, in lists you can scroll on a phone, and then hands you somebody good doing it on camera. Read the section, watch the clip, move on.
One more thing worth saying out loud. Raku is one of the least standardized things in all of ceramics. Ask ten potters how long a pot stays in the can and you will get ten answers, all of them defensible, several of them contradictory. The videos on this page do not always agree with each other and they do not always agree with us. That is not a problem to fix. Where our way differs from what you are about to watch, we say so in a note like this one.
This is what those notes look like. They are not corrections. They are just us being straight that there is more than one right answer, and telling you which one we picked.
The definition
Raku is a firing, not a look.
People think raku means crackle and copper. It does not. Raku is a way of firing, and the crackle and the copper are things that happen to fall out of it.
Here is the whole definition. You fire a bisqued, glazed pot to a low temperature, somewhere around 1800 degrees Fahrenheit rather than the 2200 a stoneware kiln reaches. Then, while it is still glowing and the glaze is still molten, you open the kiln and take the pot out. That is it. Everything else people call raku is a variation on those two sentences.
What almost everybody does next, at least in this country, is drop the glowing pot into a metal can full of paper and shavings, which catches fire instantly, and then slam a lid on it. The fire eats all the oxygen inside the can in a few seconds and then starts pulling oxygen out of anything else it can find, which happens to include your glaze. That step is called post-fire reduction and it is where the strange colors and the black crackle come from.
The part almost everybody gets wrong
That reduction can is not Japanese. Raku started in Kyoto in the 1500s, when a tile maker named Chojiro was asked by the tea master Sen no Rikyu to make hand formed tea bowls for the tea ceremony. They were low fired and pulled from a small kiln while glowing, and the warlord Toyotomi Hideyoshi later gave Chojiro’s son a seal bearing the character raku, which is roughly “ease” or “enjoyment.” That became the family name, and that family is still making the work sixteen generations later.
The smoke can arrived four hundred years later and about six thousand miles west. An American potter named Paul Soldner started putting hot pots into combustibles around 1960, and what came out of that is what the rest of the world now means by the word. Traditional Japanese raku has no reduction chamber in it at all.
Some potters are careful to call the western version “raku style” or “American raku” out of respect for the family that owns the name. Others use raku for all of it. Both camps are being reasonable. We use raku for the firing and say Japanese raku when we mean the original.
How To Make Raku Pottery - A Step-by-Step Beginner Guide
Pottery Crafters
The clearest single overview on YouTube. He builds the pot, glazes it, fires it and reduces it, and he narrates what he is looking for at every stage rather than just showing you the fire. Watch it on YouTube.
The physics, briefly
What is actually happening to your pot.
Every rule further down this page comes out of this one chart. A normal glaze firing takes ten hours to go up and twelve to come down. A raku firing takes an hour to go up and about four seconds to do most of its coming down.
- The climb. Forty five minutes to an hour and a half from cold. That is fast for a kiln, and it is fast on purpose, but it is also why the first load of the day always takes longest.
- The hold. A few minutes parked at temperature. This is the step beginners skip and then wonder why their glaze came out rough. Holding lets the melt smooth out and settle onto the pot.
- The pull. From near 2000 degrees to open air in about four seconds. Nothing else in ceramics does this. Every clay rule on this page exists because of this one moment.
- The sealed can. The fire burns the oxygen out, then starts stripping oxygen out of the metal oxides in your glaze. Copper carbonate goes to copper metal and flashes red and gold. Carbon soaks into every unglazed surface and turns it black.
- The water. A second shock, and a deliberate one. It freezes the reduced state in place before oxygen can get back in and undo it.
Why raku crackles, in one paragraph.
Glaze and clay shrink at different rates when they cool. Normally that is a problem you spend years engineering away, because a crazed glaze on a mug is a defect. In raku it is the point. The glaze cools faster than the body underneath it, cannot keep up, and cracks into a web. Then you put the pot in smoke, and the smoke crawls into every one of those cracks and stains them black. Crackle is not something in the glaze. It is a fault line with soot in it.
Reduction here is not the same word you know from a gas kiln. In a gas firing you starve the flame while the pot is still climbing, and the atmosphere changes the chemistry as the glaze matures. In raku the pot is already fired. You are changing the chemistry afterward, in the few minutes while the glaze is still soft enough to care. Same word, different event, and mixing them up is why people expect gas reduction results from a raku can.
Step one
Start with clay that can take the shock.
More raku pots are lost to the wrong clay body than to anything else, and the loss is not close. You cannot fix this later, and no amount of careful firing rescues a pot that was made out of the wrong thing three weeks ago.
More raku pots are lost to the wrong clay body than to anything else, and it is not close. There is one question that settles it, and you answer it with your hands: can you feel grit in the clay? Gritty and open survives. Smooth, dense and lovely splits. That is the whole test.
What you want
- Grog, or something like it. Grog is fired clay ground back up and mixed into the body. It works like a few thousand tiny expansion joints, giving the stress somewhere to go.
- An open body. Coarse, sandy, a bit gritty in the hand. Open bodies let steam and stress move through them instead of building up.
- Low shrinkage. The less a body wants to move, the less it minds being told to move fast.
- Some tolerance for being underfired. Raku temperatures are hundreds of degrees below where a stoneware body wants to be, so it will stay porous. That is expected.
What loses pots
- Smooth porcelain. Dense, tight, no grog, nowhere for the stress to go. It splits. People do fire porcelain raku successfully and they are working much harder than you are.
- Anything very plastic and very fine. The qualities that make a body lovely on the wheel are mostly the same qualities that make it fail here.
- A body you cannot identify. If you do not know what it is, you do not know what it does at 1800 degrees.
- Reclaim of mixed bodies. Fine for practice pots, genuinely unpredictable in a raku kiln.
What we use here, and why it is only two.
We recommend exactly two clay bodies for raku out of the eight we carry: B-Mix with Grog and Berlin Gray. It is not a close call and we are not being precious about it. Those two survive, the rest of the shelf mostly does not, and a raku workshop is a bad place to run an experiment you did not plan.
Plenty of studios buy a dedicated raku body, usually a very open, heavily grogged, talc bearing clay sold under a name with the word raku in it. Those are excellent and they throw like sandpaper. Other potters swear you can raku almost any stoneware if you preheat it gently and pull it slowly, and they are not lying, they are just accepting a higher loss rate than we want a room full of people to accept at once.
Raku Clay: What You Need To Know
Tinker & Think
Twenty minutes of clay theory compressed into nine. He is good on why grog works and honest that plenty of bodies nobody recommends will survive a firing anyway. Watch it on YouTube.
Step two
Build it so it can survive the pull.
Most pots that fail at a raku firing failed weeks earlier, at the wheel or the table, for reasons that were already baked into them. These are the eight decisions that decide it, made long before anybody lights anything.
Most pots that fail at a raku firing failed weeks earlier, at the wheel or the table. These are the five decisions that decide it, made long before anybody lights anything.
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Keep the walls even, top to bottom
Thick spots and thin spots cool at different speeds, and all of that stress piles up exactly where the two meet. It is why so many raku failures crack in a clean ring rather than somewhere random. Even walls give the whole pot one cooling curve instead of three fighting each other.
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Trim the foot to match the walls
A heavy base under thin walls holds its heat much longer than everything above it. The two halves cool at completely different rates and the pot lets go right where they meet, which is why so many beautiful pieces come apart just above the foot. Trim until the bottom feels like the same pot as the rest of it.
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Give the stress nowhere to gather
Two jobs, one idea. Soften every sharp interior corner with a rib or a damp finger so stress spreads across a curve instead of picking one line to split along. And run an extra coil down the inside of every handbuilt seam, blended until you cannot find it with a fingertip. A seam you can still feel is a crack waiting for an excuse.
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Round off every inside corner
A sharp angle inside a form funnels stress down into a single line. Soften interior corners with a rib or a damp finger and the stress spreads across a curve instead of picking one place to blow out. It costs about thirty seconds and it saves pots.
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Reinforce every seam with a blended coil
Handbuilt seams are the first thing to let go under thermal shock, and they let go loudly. Run an extra coil down the inside of every join and blend it until you cannot find it with a fingertip. If you can still feel the seam, it is a crack waiting for an excuse.
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Compress the floor properly
An uncompressed floor cracks in a normal glaze firing. In raku it does not stand a chance. Compressing the floor is the cheapest insurance on this whole list.
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Think hard before you close a form
Narrow necks and closed forms are the ones that burst, because they trap steam and pressure with nowhere to go. They can absolutely be fired, and they are handled differently at every stage, so decide now rather than being surprised later.
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Keep it small enough to move fast
Somebody has to carry this thing, glowing, on the end of a pair of tongs, across open ground, in one movement. Big pieces are dramatic and they are also the ones that get dropped. Tall and skinny travels better than wide and heavy.
Closed and narrow necked forms can be fired and they are handled differently at every stage, so decide now rather than being surprised later.
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Get it bone dry, then bisque it
Any moisture still hiding inside becomes steam at temperature and leaves through the nearest wall, taking a piece of your pot with it. We bisque to cone 05. A pot that felt dry a week ago is a far safer bet than one that felt dry yesterday.
Bisque temperature is a live argument. Some raku potters bisque low, around cone 08 or 06, on the theory that a more porous body handles shock better and takes glaze more thirstily. Others bisque to cone 04 for strength, because a raku pot gets handled hard. We bisque everything to cone 05 for the same reason we do most things, which is that one temperature for the whole studio beats six.
Step three
Glazes, and how to put them on.
A raku glaze is not a category of chemistry so much as a category of use. The short answer is that a raku glaze is any glaze that melts at the temperature you are firing to and does something interesting when you take the oxygen away from it.
A raku glaze is any glaze that melts at the temperature you are firing to and does something interesting when you take the oxygen away from it. Crackle bases, coppers and metallics, copper matte, flashing slips. And bare clay, which takes the smoke and goes deep black, and is the most underrated surface in raku.
Crackle bases
Clear or white, high in alkaline flux, and formulated to craze deliberately. The glaze is the canvas and the smoke does the drawing. This is the classic white raku pot with a black web across it.
Copper and metallic
Loaded with copper carbonate, and sometimes iron or cobalt alongside it. Reduction strips the oxygen back off the metal and you get reds, golds, greens and oil slick iridescence. Also the least repeatable thing on this list.
Copper matte
A heavy, dry copper coat that is barely a glaze at all. Almost all of the color development happens after the can, when you let air back onto it in a controlled way.
Flashing slips and terra sigillata
Not glazes. Thin clay coatings that take smoke beautifully and stay matte. Burnished terra sigillata is what makes horsehair lines read sharp instead of blurry.
Underglaze and oxides
Both work, both behave differently than they do at cone 5½. Colors that need oxygen to develop will let you down in a reduction can. Test before you commit a piece you love.
Bare clay
The most underrated surface in raku. Anywhere glaze does not reach, carbon soaks in and goes deep black, and the contrast between that black and a flashed copper is most of what people react to.
Applying it: thicker than feels right.
- Three coats minimum, often more. Raku glazes generally want to go on heavier than a cone 5½ brush-on glaze. Thin coats give you patchy, dry, disappointing surfaces.
- Let each coat dry before the next. Wet on wet lifts the coat underneath and you end up with bare patches you will not see until the pot is glowing.
- Keep the foot and about a quarter inch above it clean. Molten glaze plus a kiln shelf equals a pot you own permanently.
- Use resists on purpose. Wax, tape, rubber bands, liquid latex. Anywhere the glaze does not reach, the smoke gets in. Resist is how you get pattern and edge instead of an even coat.
- Know what is on each pot. Write it down. Different glaze families want different temperatures, and at the firing somebody will ask you.
- Do not mix families on one piece unless you are certain they fire to the same temperature. Mixing is the fastest way to ruin a good pot and sometimes the rest of the load with it.
- One glaze family per pot, written down. Different families want different temperatures, somebody will ask you at the firing, and mixing them is the fastest way to ruin a good pot and sometimes the load with it.
Steven Branfman, who wrote the book most raku potters own, argues that a raku glaze is simply any glaze used in the raku process, and that stoneware glazes, low fire commercial glazes, china paints and plain oxides all have a place in it. He is right, and experienced potters get remarkable results doing exactly that. Our rule about staying inside one family is a studio rule for firing eighteen people’s work in one night, not a law of ceramics.
We carry raku specific glazes in the building alongside the rest of the collection. If you want to see what is on the shelf, the glaze collection page and the glaze finder both cover it.
Beautiful Raku Glaze Recipe
Tinker & Think
Mixing from raw materials is not something you will do here, and watching it is still the fastest way to understand why raku glazes behave the way they do. The alkaline base doing the crackling is the part to pay attention to. Watch it on YouTube.
Step four
The firing itself.
A raku kiln is a simple, brutal machine. Almost all of them are a lightweight fiber shell that lifts off or hinges open, sitting on a base, with one or two propane burners pointed in at the bottom.
Somebody else is probably running the kiln. These are the three parts of it that are your job.
Top hat and lift off
The most common studio kiln. A fiber lined shell on a frame, raised straight up off the load with a pulley or by hand. The whole load is exposed at once, which is why the choreography matters.
Trash can and barrel
A metal can lined with ceramic fiber blanket. Cheap, effective, and the way a lot of people fire at home. Every principle on this page applies unchanged.
Updraft and front loading
Brick built, slower to heat, holds temperature better. Nice for bigger work, harder to unload quickly, which is the tradeoff.
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Load with the unload in mind
Pieces go in spaced apart, not touching each other and not touching the walls, on posts and shelf as needed. The real decision is order: whoever is pulling which pot should be able to reach it without crossing anybody else’s path.
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Rehearse the unload cold
Everybody picks up their tongs, grabs their piece the way they intend to, turns the way they intend to turn, and walks where they intend to walk, while the kiln is open and stone cold. Tongs behave differently on different forms and finding that out now is much better than finding it out later. This is the single biggest difference between a firing that looks smooth and one that does not.
Pick up your tongs and rehearse the whole thing while the kiln is open and stone cold: your grab, your turn, your walk. Tongs behave differently on different forms and now is the time to find that out.
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Climb, and do not rush the start
Bring it up gently for the first few minutes, especially if the pots are cold or the weather is. After that, raku climbs fast on purpose. Figure on forty five minutes to an hour and a half, and expect the first load of the day to take the longest because everything is starting from cold.
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Read the glaze, not just the pyrometer
A pyrometer tells you the air temperature and the glaze tells you the truth. Watch through the spy hole. The surface goes from dry and matte, through a stage that looks like orange peel, to wet and glassy and reflective. When it looks like it is covered in syrup, you are there.
Skipping the hold at the top is the most common reason a glaze comes out looking dry.
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Hold at temperature
A few minutes at the top, in as tight a window as you can manage with a hand valve on a propane line. This is what lets the melt smooth out and settle onto the pot instead of arriving rough. Skipping the hold is the most common reason a glaze comes out looking dry.
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Get everyone geared and set before you open
Goggles, apron, gloves, all the way on, five minutes before you expect to be at temperature. Cans open, nests built, bags of combustibles parked where they can be grabbed. If the kiln has to wait for a person, it climbs past temperature and somebody’s glaze pays for it.
Temperature is the thing you will see argued about most. A lot of studios fire glazed raku somewhere near 1750 to 1800 degrees Fahrenheit, roughly cone 06, and drop to about 1250 for horsehair and obvara. Ours runs hotter, up near 2000 by the time the lid comes off. Neither is wrong. What matters far more than the number is that you hold there and that you know what your own glazes want.
RAKU FIRING - the CRAZIEST way to finish pottery!
Jonthepotter
A complete firing at real speed, including the parts that go wrong. If you want to know what the twenty seconds after the lid comes off actually feel like, this is the one. Watch it on YouTube.
Step five
The pull, and the can.
This is the part people come for and it lasts about ninety seconds. Everything up to now was preparation for it, and everything after it is cleanup.
Build the nest first
A kiln brick goes in the bottom of the can so the pot has something to sit on that is not the metal. On top of that, a loose nest of torn newspaper with pine shavings and animal bedding sprinkled through it. Loose is the operative word. Packed combustibles smother instead of flaring.
A kiln brick in the bottom of the can, then a loose nest of torn newspaper with pine shavings and animal bedding through it. Loose is the operative word. Packed combustibles smother instead of flaring.
Fill a bag, and tear it
A paper lunch sack packed with more of the same, parked right beside your can. Rip it down one corner before you need it so it dumps instantly rather than fighting you while you are holding a glowing pot in your other hand.
Lift, pivot, set down
Get the tongs on the piece the way you rehearsed, come straight out, turn the way you rehearsed, and set it on the brick in the nest. It will burst into flame the instant it lands. That is supposed to happen.
Feed it, then seal it
Sprinkle or dump the bag over the pot, throw the crumpled bag in too, let the flames climb to their peak and just start to settle, then put the lid on and stomp the edges down so the whole thing seals. The starved atmosphere inside is the entire point.
The burp, and why people argue about it
Five or ten seconds after sealing, some potters crack one side of the lid to let a rush of oxygen in. It catches, and a fireball comes out the side of the can, and then the lid goes straight back down. The theory is that a quick hit of oxygen followed by another hard reduction pushes copper further toward the flashy end of its range.
Potters argue about whether it changes anything at all. Plenty of very good ones swear by it. Plenty of others have run tests and say the difference is noise. It also adds real danger, because a fireball comes out of a specific side at a specific moment, so nobody should be standing there and nobody should be inhaling. Ask before your first one.
Time in the can is completely unsettled. Some potters pull the lid at five minutes. Some leave it an hour. Some never seal at all and just let a pot smoke in the open, which gives softer, greyer results. We go about twenty minutes, which is long enough for the chemistry to finish and short enough that we are also loading the next kiln while it sits.
Everything about this is hotter than it looks.
The number one way people get burned at raku is not the kiln and it is not the tongs. It is the can and its lid, twenty minutes later, sitting there looking like it has been quietly doing nothing. Gloves on for the lid, the can, and the pot inside it, every time. If you are firing with us, the full rule set and the safety certification live on the raku safety and certification page.
The number one way people get burned is not the kiln and not the tongs. It is the can and its lid, twenty minutes later, looking like it has been quietly doing nothing. Gloves on, every time.
Step six
Water, or no water.
Opening the can is the second reveal of the night, and what you do in the next thirty seconds still changes the pot.
Lid off, gloves on, lift the piece out and brush the ash and debris off it. If you want the classic crackle, get down close and listen. It sounds like popcorn in a microwave: fast ticking at first, then the gaps between the ticks stretch out. When the gaps get long, it is time.
Quenching in water stops the pot where it is. Oxygen is trying to get back into your reduced glaze the whole time it is cooling in air, and cold water ends that argument immediately. It is why quenched pieces read brighter and keep more of their metallic flash. Wide open forms, bowls and anything with a big mouth go straight into the tub.
Quenching stops the pot where it is, before oxygen can creep back into the reduced glaze, which is why quenched pieces read brighter. Wide open forms, bowls and anything with a big mouth go straight into the tub.
Air cooling gives you a softer, more muted, often more interesting surface, and it lets the crackle keep developing for another minute or two. Some potters never quench anything and their work is beautiful. It is a taste decision, not a correctness one.
The one rule with no flexibility in it
A narrow necked or closed form never goes into water while it is hot. Water pours in through the neck, flashes to steam instantly, the steam has nowhere to go, and the piece bursts. Those get sprayed instead: several passes into the inside with a pressurized sprayer to bring the temperature down, and only then into the tub to finish cooling. A sprayed piece is not done just because the outside feels cool, and nobody puts a bare hand on it before it has been submerged.
Everything else is quick. A couple of minutes floating in the tub, a tap with a fingertip, and it is yours.
Then scrub it. A pot out of the tub is covered in soot and looks like nothing. Take a scour pad, water and a mild abrasive to the glazed areas until the color comes up, and leave the bare clay alone, because the black there is carbon soaked into the body and you want it.
Step seven
Cleaning it up, and deciding how far to go.
A pot out of the tub is covered in soot and ash and looks like nothing. This step is where it turns into the thing you saw in your head, and it is the step almost nobody films.
- Scrub the carbon off the glazed areas. A scour pad, water, and a mild abrasive cleanser. Work at it. The soot on top of the glaze is not the effect, it is covering the effect.
- Leave the bare clay alone. The black on unglazed areas is carbon soaked into the body and you want that. Scrubbing hard there just makes it patchy.
- Decide about the crackle. Straight out of the can the lines are grey. India ink, or shoe polish, or a graphite rub worked into the surface and wiped back darkens them to a proper black. Some people love it and some people find it heavy handed.
- Seal it, or do not. A wax or an acrylic sealer deepens the color, protects the surface from handling, and slows the copper down. It also puts a film between you and the clay. Try both on two pots before you commit to a habit.
- Expect it to keep changing. Copper reds are the least stable colors in ceramics. A flashy pot can go quieter over months as oxygen gets back into the surface. Sealing slows this. Nothing stops it.
There is a real school of thought that says do nothing at all: no ink, no wax, no polish, let the pot be exactly what came out of the can and let it age. There is another that treats finishing as half the work. We do the India ink step back at the studio during a normal class rather than out at a firing, because it is fussy and it wants a clean table.
How I Polish and Protect Raku Pots
Doug Rubenstein
The step almost nobody films. Scrubbing, sealing and what each option does to the surface, from somebody who sells the results. Watch it on YouTube.
Variations
Five other ways to raku.
Everything above describes glaze raku, which is what most workshops run and what most people mean. These five are its close relatives. They use the same kiln, the same gear and most of the same rules, and they produce work that looks nothing like each other.
Naked raku
The pot comes out with no glaze on it at all, which is the joke in the name. You brush on a resist slip, then a thick crackle glaze over the top. In the can, the glaze crazes and the smoke drives through those cracks into the slip and stains the clay underneath. Then both layers flake off, sometimes in the water, sometimes with a fingernail, and what is left is bare burnished clay with a black web drawn on it. It is the most technically fussy thing on this list and the most striking when it works.
Naked Raku ~ The Full Monty
ArranEye
Five and a half million people have watched this, and it earns every one of them. He works through slip, glaze, firing and the peel, and the moment the shell comes off is worth the whole video. Watch it on YouTube.
Horsehair and feather
No glaze, no reduction can, and a much lower temperature. The pot is burnished first, usually with terra sigillata, and pulled out somewhere around 1100 to 1300 degrees. Then you lay horsehair, feathers, or a sprinkle of sugar directly onto the hot surface and it carbonizes on contact, leaving a wandering black line exactly where it touched. Too cool and nothing marks. Too hot and the carbon burns straight back off. The window is narrow and finding it is most of the skill.
Super Quick Terra Sigillata Plus Feather and Horsehair Raku Firing MARCIA SELSOR
Ceramic Arts Network
Two minutes, no filler. She burnishes with terra sigillata first, which is what makes the smoke lines read sharp instead of muddy, and then lays hair and a feather on a hot pot. Watch it on YouTube.
Copper matte
A heavy dry copper coating rather than a glossy glaze, and the trick is that most of the color arrives after the can. You reduce it, then let air back onto the surface in a controlled way, fanning it or misting it with water while it is still hot, and iridescent reds, golds, greens and purples bloom across it as it reoxidizes. Do it too fast and you get grey. It is the most hands on finish in raku and the one people chase hardest.
How to Make Copper Matte Raku
The Pottery Wheel
Copper matte is the one where the work happens after the can, and she shows the fanning and spraying that decides whether you get red, gold, green or a flat grey disappointment. Watch it on YouTube.
Obvara
A Baltic technique, several hundred years old, and completely unlike everything else here. You ferment a mixture of flour, yeast, sugar and water for a few days until it is alive and sour. The pot comes out of the kiln around 1650 degrees and gets plunged straight into the bucket. The mixture scorches onto the surface instantly in browns and golds and near blacks, then the piece goes into water. No glaze anywhere. The results look like something that grew rather than something that was fired.
Obvara Raku Firing (Narrated Version)
Doug Rubenstein
The narrated cut, which is the one to watch. He covers the ferment, the temperature window and the dunk, and he is refreshingly blunt about how much of it is out of your hands. Watch it on YouTube.
Saggar
The reduction happens in a sealed container packed around the pot rather than in a can afterward. You bed the piece in sawdust, salts, copper wire, seaweed, banana skin, ferric chloride, whatever you are willing to experiment with, close the saggar and fire it. Every material leaves its own mark on the surface. Of everything on this page it is the least controllable and the most fun to plan.
Saggar Firing
Cantley Pottery
Saggar is the loosest of all of these, and this is a calm walk through packing a container with combustibles and salts and letting the container do the reducing instead of a can. Watch it on YouTube.
Purists will point out that horsehair, obvara and saggar are not really raku at all, they are alternative firing techniques that happen to use raku kilns and raku tools and get run at raku workshops. That is a fair point and we are going to keep grouping them anyway, because the person holding the tongs does not care much about taxonomy.
Not optional
Safety, said plainly.
Raku is the only thing in ceramics where a mistake burns somebody. Not ruins a pot. Burns a person. Everything below is standard across every studio that runs this well.
What you wear
- Closed toe shoes, long pants, hair tied back. Every person, every time.
- Natural fibers only. Cotton, denim, wool. Fleece, nylon and polyester do not burn so much as melt, and melted fabric sticks to skin.
- Nothing loose or dangling. No open sleeves, no scarves, no swinging jewelry.
- Goggles, a welding apron and full length welding gloves, fully on, before the kiln is at temperature.
- Glasses stay on and the goggles go over them. Do not swap to contacts for this.
How you move
- People come before pots. If it comes to it, set the piece down or let it go.
- Never lean over to pick something up during an unload. Whatever you dropped will still be there in twenty minutes.
- Not in this firing? Stand well back behind the furthest cans and watch from there.
- Somebody will be shouting orders and it is not personal. If you hear your name, do the thing immediately.
- Nobody participates under the influence of anything that changes their balance, judgment or reaction time.
- Do not breathe what comes out of a can. Take your breath of fresh air first, then go near the lid.
- The can and the lid stay dangerous long after they look boring. Gloves on for the can, the lid and the pot inside, every time. This is where most burns happen.
- Fire it outdoors, always, and only trained people load the kiln between firings.
Smoke and fumes
- Do not breathe what comes out of a can. Hold your breath until your face is clear of it.
- Take your breath of fresh air first, then go near the lid. People get caught leaning in and inhaling on reflex.
- A paper mask helps with particles and does nothing for gases. If fumes are your concern you want a cartridge respirator with organic vapor cartridges.
- Fire it outdoors. Always. This is not a thing that happens inside a building.
Heat, after the excitement
- The can and the lid stay dangerous long after they look boring. This is where most burns happen.
- Only trained people load the kiln between firings. The air alone will burn you.
- Extinguishers, a hose and buckets of water at the firing area, with specific people assigned to them.
- Cold running water and a burn kit on site, and you say something the second it happens rather than after your pot is safe.
If you are firing with us
Our full rule set, the choreography we use, the gear we supply and a certification you can carry are all on the raku safety and certification page. It takes about fifteen minutes and it makes the night make sense before you are standing in it.
Troubleshooting
When it goes wrong, and it will.
The raku gods take a percentage. That is genuinely part of the deal and it always will be. But most losses have a cause, and most causes are on this list.
It cracked in a clean ring just above the foot
A heavy base under lighter walls. The thick part held its heat while the thin part let go of it, the two halves cooled at different rates, and the pot split exactly where they met. Trim the foot until the bottom feels like the same pot as everything above it.
It burst apart in the can or in the water
Almost always one of three things. Trapped moisture that flashed to steam. A closed or narrow necked form that took on water while hot. Or a clay body with nothing open in it to absorb the shock. The first is a drying problem, the second is a handling rule, and the third cannot be fixed after the fact.
The colors came out dull, brown or grey
Usually not enough reduction. Either the can did not seal properly and oxygen kept feeding in, or the piece sat in open air too long between the kiln and the can, or there were not enough combustibles to get a real fire going. On copper matte specifically, dull grey usually means it reoxidized too fast rather than too slow.
The glaze looks dry, rough or unmelted
It came out too early or it never got a hold at temperature. A raku glaze wants to look wet and glassy through the spy hole before you open anything. If it looked like orange peel when you pulled it, you were a few minutes short.
I got no crackle at all
Either the glaze was not a crackle base, or the pot cooled too slowly for the glaze and body to argue with each other, or the smoke never got into the cracks because the reduction was weak. Air cooling for a minute before the can gives crackle more time to open up.
There are bare patches where glaze should be
Crawling, and it is nearly always application. Glaze went on over dust or a greasy fingerprint, or a wet coat lifted the coat under it, or it was simply too thick in one spot. Wipe bisque down before glazing and let every coat dry properly.
The whole thing came out black
Often just carbon sitting on top of the glaze rather than a failure. Scrub it properly with a scour pad and a mild abrasive before you decide. If it is still black after real scrubbing, the glaze was probably too thin to cover and the body underneath took the smoke.
It looked incredible and then faded over a few months
Copper reoxidizing. Copper reds are the least stable colors in all of ceramics and they slowly give up their flash as oxygen works back into the surface. A wax or acrylic sealer slows it considerably. Nothing stops it, and plenty of potters think the aged version is the better one.
It survived, but it leaks
It is supposed to. See the next section.
The honest part
What a raku pot is actually for.
This is the conversation nobody wants to have at the end of a great night, so we would rather have it now, before you make something you were planning to drink out of.
Read this before you make something you were planning to drink out of.
Raku is not food safe and it never will be. Not with a sealer, not with a liner glaze, not if you are careful. The body is fired hundreds of degrees below vitrification so it stays porous, the glaze is deliberately crazed so it has a network of cracks running through it, and raku glazes routinely carry copper and other metals in quantities that have no business near food. Those three facts stack.
It is not watertight. Water will pass through the body over hours or days. A raku vase full of flowers is a slow leak sitting on your furniture. If you want to use one, drop a glass or plastic insert inside it and fill that instead.
Raku is not food safe and it never will be, and it is not watertight. The body stays porous, the glaze is deliberately crazed, and raku glazes routinely carry copper. A vase wants a glass insert inside it.
It is not for the dishwasher, the oven, the microwave or the freezer. Anything that heats or cools it fast is asking it to do the one thing it already survived once, and it will not survive it twice.
It is not weatherproof. A porous pot outside in Utah will take on water and then freeze, and freezing water inside a wall is how pots come apart. Planters need a liner and a winter indoors.
And it is not for the dishwasher, the oven, the freezer or the back yard. Anything that heats or cools it fast is asking it to survive the one thing it already survived once.
So what is it for
Looking at. Holding. Being an object. Raku is the branch of ceramics that gave up function entirely in exchange for surfaces you cannot get any other way, and it made a good trade. Vessels, sculpture, lidded jars, wall pieces, things that sit on a shelf and stop people mid sentence. Nobody has ever been disappointed by a raku pot for the reason they thought they would be.
Looking at. Holding. Being an object. Raku gave up function entirely in exchange for surfaces you cannot get any other way, and it made a good trade.
Keep this open
The phone list.
Everything above, compressed into two lists you can hold in one hand. Print button is at the top of the page if you would rather have it on paper.
Weeks before, at the studio
- Built in a grogged or open clay body
- Walls even from the rim to the foot
- Foot trimmed to match the wall thickness
- Interior corners rounded, not sharp
- Every seam reinforced with a blended coil
- Floor compressed
- Bone dry, then bisqued
- Glazed with raku glazes, three coats or more
- One glaze family per piece, and written down
- Foot and a quarter inch above it wiped clean
At the firing
- Closed toe shoes, long pants, hair back, natural fibers
- Rehearse your grab, your turn and your walk while it is cold
- Nest built: brick, then loose paper and shavings
- Bag filled and torn down one corner, parked by your can
- Fully geared five minutes before temperature
- Glaze looks wet and glassy before anybody opens anything
- Lift, pivot, set down. People before pots
- Feed it, let the flames peak, seal the lid, stomp it down
- Twenty minutes closed, and no reaching into the kiln
- Gloves on for the can, the lid and the pot. Always
- Open mouths into the water, narrow necks get sprayed first
- Scrub, admire, and help clean up
Go do it
Reading about it only gets you so far.
You can know every word on this page and still not know what it is like when the lid comes off and a wall of heat hits you in the face and everything inside is glowing. That part does not transfer. You have to be standing there.
You can know every word of this and still not know what it is like when the lid comes off and everything inside is glowing. That part does not transfer.
We run raku workshops every couple of months. They show up on the studio calendar when they are scheduled, and they fill.
This was the short version. There is a much longer one behind the toggle at the top of the page, with the history, the chemistry, five other ways to raku and eight more videos.
Watch the studio calendar
Workshops, classes and events, all in one place. The next raku date appears here first.
Get raku safety certified
Our rules, the full choreography, a ten question check and a card you can carry. About fifteen minutes.
One last thing, and every raku potter will tell you the same. Bring one piece you would be genuinely gutted to lose, and one you would not. You will have a better night either way.
Which version would you like to print?
Videos come out as a labelled box with the title and channel to search for, since paper does not play them.