The five stages of clay
Clay is one material from the bag to the shelf. What changes is how much water is in it, and then how much heat has been through it. Those two numbers decide what you can do to a piece, what you can still fix, and what you have permanently lost.
Three of these stages are a loop you can walk in both directions. Two of them are fire, and fire does not run backwards. Here is the short version.
Here are all five, how to tell which one your piece is in tonight, what to do with it while you are there, and the two doors that only open one way.
Which version would you like to print?
Videos come out as a labeled box with the title and channel to search for, since paper does not play them.
Three stages are a loop. Two are fire.
Wet, leather hard and bone dry are not three materials. They are one material holding three different amounts of water. Take water away and you move forward. Add water and you move back. Nothing has been decided yet, and every mistake in there is free.
Why this page reads and plays.
A video carries what a sentence gets wrong: the timing, how hard a hand is actually pressing, the sound a rib makes when a wall finally goes even. A written list carries the order, and the order is what you need later, at the wheel, with the video closed and both hands full. So every stage below has both. Read the list, watch the maker, then go and do it with your phone face down.
The videos are not ours. They are from makers who explain their part of this better than most, and each one opens on YouTube in a new tab if you would rather watch it there.
Six minutes for the whole arc
The fastest useful tour of the whole sequence, with real pots in hand at each stage rather than diagrams. Worth watching before anything else on this page.
Two things to listen for. He handles each stage differently, and you can see it in his grip. And he is candid about how quickly the leather hard window shuts, which is the single fact most new potters learn the expensive way.
Other studios count the stages differently, and you will see lists of six or seven online. Ours is five, and the difference is bookkeeping rather than chemistry.
Five stages, one screen.
What each one feels like, what it will let you do, and the exact moment it stops being your decision. Wet, leather hard and bone dry are one material at three water levels, so you can move in either direction. The two firings only run forward.
| Stage | What it feels like | What you do here | Can you go back? |
|---|---|---|---|
| 01 Wet and plastic | Cool and soft. A thumb sinks in and the dent stays. | Wedge it, then make the thing. Even walls. Compress the floor and the rim. Wrap it before you leave. | Completely |
| 02 Leather hard | Cool, like hard cheese. A fingernail dents it, a thumb does not. | Trim the foot, attach handles, carve, sign it. The window is about a day. | Yes, slowly |
| 03 Bone dry | Pale, chalky, room temperature on your cheek, and the most fragile it will ever be. | Hunt for cracks, sand lightly, dust it off, and put it on the ready for bisque firing table. | Only as scrap |
| 04 Bisque | Hard, light and thirsty after the first firing at cone 05. It drinks water off a finger. | Rinse the dust off, glaze it, keep the bottom bare. Nothing gets added or reshaped now. | No |
| 05 Stoneware | Glazed, glassy and hard as stone after the second firing at cone 5½. | Check the foot for sharp spots, test it if it has to hold liquid, and pick it up within two weeks. | Never |
Three habits that save more pots than skill does
- Even wall thickness. A crack is two parts of one pot shrinking at different times. Same thickness all the way round means the whole thing dries at the same rate, and a piece that dries evenly mostly survives.
- Wrap anything you are coming back to. Plastic does not stop a piece drying. It slows the thin fast parts down so the thick slow parts can catch up. Plastic sheeting is free here, at every level.
- The cheek test, every time. Hold the piece against your cheek. Cool means water is still evaporating out of it, whatever the surface looks like. Water still inside at cone 05 turns to steam and takes the piece apart.
The one line worth keeping. Everything before the first firing is recoverable. Nothing after it is. So be bold with wet clay and careful about what you send to the kiln, which is the opposite of what most people do.
The longer version of this page takes each stage on its own: how to tell it apart from the one either side of it, what to do while you are there, what ends a piece, and seven more videos. The toggle at the top switches to it.
Bone dry
Everything that can evaporate on a shelf already has. Pale, chalky, room temperature and the most fragile the piece will ever be. It is also the most misidentified stage in the building, and getting it wrong is the one mistake that can take other people’s work down with yours.
How to tell
- The cheek test. Hold it against your cheek or the inside of your wrist. Cool means water is still leaving it, because evaporation carries heat away with it. Room temperature means it is done. This is the whole trick, and it takes one second.
- It is visibly paler than it was, and lighter in the hand.
- A fingernail leaves no mark at all.
- If you truly need to know, weigh it two days running. A piece that has stopped losing weight has stopped losing water.
Bone dry
Water: the free water is gone. The chemically bonded water is still in there.
Window: indefinite. It will sit for months without getting worse.
Reversible: only as scrap, in a bucket.
Costs you: nothing yet. Bisque firing is free here.
Bone dry does not mean zero water. The water bonded into the clay mineral itself is still sitting in the crystal, and no amount of shelf time reaches it. Removing that is the first firing’s actual job. What bone dry means is that everything a shelf can take out has been taken out, which is the condition a kiln needs before it starts.
What you do here
- Hunt for cracks before you fire it. Every join, the rim, the inside of the floor, and the outside where the wall meets the base. This is the last moment a crack is free information rather than a finished disappointment.
- Sand lightly. Lightly. Fine wet-dry paper or a green scrubby, gentle pressure, and only where a sharp edge or a ridge needs knocking back. Bone dry clay gives way faster than you expect.
- Wipe the dust off with a barely damp sponge. Dust left on the surface is a glaze defect waiting for its moment, and it also makes the piece easier to inspect.
- Make the bottom smooth. Anything sharp now is sharp forever, and it will live on somebody’s table.
- Give it longer than you think. Thick walls, closed forms, anything with a foot ring and anything made from a porcelain-heavy body hold water in the middle long after the surface reads dry. When in doubt, another few days costs nothing.
- Then put it on the ready for bisque firing table. Place it as far left as you can reach, without ever touching or moving somebody else’s piece. Every pot on that table is somebody’s six weeks.
What ends a piece here
- Handling it like it is still strong. It is the weakest it will ever be. Handles snap off, rims chip, and thin walls go with a thumb in the wrong place. Carry it from the base, not the handle.
- Firing it before it is dry. Water still inside at bisque temperature flashes to steam faster than it can escape, and the piece comes apart. Fragments can chip the pots stacked around it, which is why this one is not just your problem.
- Patching a crack with water and a smear of clay. It will not hold. It dries at a different rate, shrinks at a different rate, and reopens on the same line. A commercial mender is the only thing worth trying, and it is a coin flip.
- Heavy dry sanding at your table. Keep it light where you sit. Anything more than that gets done over a trash can or a clay scrap barrel, and you sweep up whatever reached the floor before you walk away.
At The Clay Hole
Bone dry work goes on the tables marked ready for bisque firing. No ticket, nothing to pay, because the bisque firing is free. Our team loads every kiln and fires when the tables fill up, so plan on one to two weeks rather than a date. Both firings happen here, or both happen somewhere else: taking a free bisque away to fire the glaze elsewhere is the one version of this that does not work.
The stage with the least to look at
Drying is mostly waiting, which is exactly why it goes wrong: there is nothing to watch, so people stop paying attention. This walks through covering, uncovering in the right order, and how to read a piece that looks dry and is not.
The part worth stealing is the habit of uncovering the thick parts first and leaving the thin parts wrapped, which is the opposite of what feels natural and is the reason handles survive.
Bisque
Fired once, to cone 05, around 1,888°F. Hard, light, thirsty and permanently ceramic. This is the stage where the material stops being clay, and it is the reason the word greenware exists to describe everything before it.
What actually happened in there
Up to about 212°F: water smoking
Any free water still hiding in the middle of a wall leaves as vapor. Kilns are held low and slow through this stretch precisely because steam expanding inside a sealed wall is what blows pieces apart.
Roughly 660°F to 1,300°F: the door
The water chemically bonded into the clay mineral is driven out of the crystal. This is the change that cannot be undone. Past this point the piece will never soften in water again, no matter how long you leave it in a bucket.
Around 1,063°F: quartz inversion
The silica in the clay body changes crystal form and briefly expands, then does the reverse on the way back down. Firing schedules slow through it in both directions, which is part of why a kiln takes as long as it does and why nobody opens one early.
Higher up: burnout, then a light fuse
Organic material in the clay burns away, which is where the smell comes from. Then the particles begin to sinter, just enough to hold the piece together and nowhere near enough to close the pores. Leaving those pores open is the entire point of stopping at cone 05.
How to tell bisque from bone dry, because they look identical on a shelf
- Sound. Tap it with a fingernail. Bisque gives a short ring. Bone dry gives a dull thud.
- A fingernail. Bone dry scratches and leaves powder. Bisque takes no mark at all.
- Water. Touch it with a wet fingertip. Bisque pulls the water in and is dry again in a second. That absorbency is the whole reason this stage exists.
- Weight and color. Bisque is lighter than it looks and often a slightly different color than the raw clay was, because iron and organics have burned.
What you do here
- Get the dust off first. A flash rinse or a wipe, seconds rather than a soak. A saturated pot has nowhere left to pull glaze water into, and the coat goes on thin and patchy.
- Glaze it. The porosity does the work: the bisque drinks the water out of the glaze and leaves the glaze sitting on the surface. That is why glaze grabs on bisque and slides off anything vitrified.
- Keep the bottom bare. Zero glaze on the foot, and stop short of the table by an eighth to a quarter of an inch depending on how much the glaze moves.
- Handle it clean. Glaze will not stick to a fingerprint, and you will not find out until the piece comes out with a bare oval on it.
- Write down what you used. A glaze card or a photo on your phone. Future you will want to make that again and will not remember a thing.
What you cannot do any more
- Add, carve, join or reshape. Nothing sticks to bisque permanently and nothing cuts it usefully. The form is the form.
- Glaze the bottom. Molten glaze welds a pot to a kiln shelf, and a kiln shelf costs hundreds of dollars.
- Assume it is unbreakable. Bisque is stronger than bone dry and it is still a thin ceramic shell. It chips, and it drops just as hard.
- Turn it back into clay. A bisque pot in a bucket of water is a wet bisque pot. That is all it will ever be.
At The Clay Hole
The bisque firing is free and unticketed. The glaze firing is the paid one: pay first, write your order number on a kiln ticket along with your name, the date, your clay and every glaze you used, put a cookie under anything that might run, and leave it on the glazeware table. Another one to two weeks, and the kiln cools for 24 to 48 hours before anybody is allowed to open it.
Glaze firing runs 5 cents per cubic inch with a $4.80 minimum. The firing cost calculator does the measuring math for you.
Stoneware
Glazed and fired a second time, to cone 5½, which is cone 5 held for twelve minutes so the work lands between cone 5 and cone 6. The glaze has melted into glass and the clay body has partly turned to glass with it. Hard as stone, waterproof, and finished in the literal sense of the word.
What vitrification actually means
Enough glass has formed inside the clay body to close the pores between the particles. The practical measure of it is absorption: the percentage of its own dry weight that a fired piece will soak up in water. Under about 3 percent is the usual standard for functional stoneware, and the clays we stock publish figures between 2.3 and 3.5 percent.
That number, and not the shine, is what decides whether a mug holds coffee for ten years or slowly weeps through its own foot. Glaze seals a surface. Vitrification seals the body underneath it, which is what matters the day a glaze crazes.
Stoneware
Fired to: cone 5½, about 2,167°F plus the heat work the hold buys.
Absorption: 2.3 to 3.5 percent across our clays.
Size: final. 10 to 14 percent smaller than the wet lump.
Reversible: not in any sense at all.
What you do here
- Run a hand over the foot. Anything sharp gets ground smooth before the piece lives on somebody’s wooden table. Ask for the grinding wheel rather than improvising.
- Look for crazing. A fine web of lines in the glaze only, with the clay under it intact, is a glaze fit issue rather than a break. On a vitrified body it is mostly cosmetic. On a thirsty one it is a slow leak.
- Test it if it has a job. Fill it, stand it on a dry paper towel overnight, and look at the towel in the morning. That is the whole test and it settles the argument.
- Write the glazes down now. Which glaze, how many coats, in what order. In three months this piece will be the one you want to repeat and the one you cannot remember.
- Take it home within two weeks. Set the reminder on the day you drop it off rather than trusting future you.
What you cannot do any more
- Undo a firing. A refire is another firing, not a reversal. It can add glaze on top of what is there and it can change the color you already have. It cannot take anything back.
- Sand a glaze smooth. You can grind a foot flat. A glazed surface is glass, and grinding it leaves a dull scar rather than a repair.
- Repair a break so it holds heat or water. Glue and kintsugi make a piece beautiful again and put it firmly in the decorative category. Nothing sticks a vitrified break back into food service.
- Get the size back. The shrinking finished when the kiln did. If the lid does not fit the jar now, it never will.
At The Clay Hole
Everything on our shelves is a mid-range stoneware body, which is why the glaze firing runs to cone 5½ rather than higher or lower. Fired work lives on the pickup shelves with a deadline card on it, and after two weeks it is most likely gone. If you are going to be away, tell somebody in a bright pink shirt before you leave rather than after.
The stage most people never learn
She runs the absorption test on camera, which turns vitrification from a word into a number you can check yourself. It is the clearest explanation online of why a shiny pot can still be a leaky one.
One difference to note: she is talking about choosing and firing your own clay, and here the clay bodies and the firing schedule are already decided for you. Watch it for the reasoning rather than the shopping.
Three kinds of water, leaving at three different times.
Once you know this, nearly every crack in this building explains itself, and so does why the stages sit where they do.
The water holding the particles apart
Wet clay is millions of tiny flat plates with water between them, and that water is the entire reason it slides into a shape instead of crumbling into one. As it evaporates the plates slide closer together and the piece gets physically smaller. That is your drying shrinkage, and it is where nearly every crack comes from.
The water sitting in the gaps
Eventually the plates are touching and cannot get closer. There is still water in the piece, sitting in the pores, but from that point on it leaves without changing the size at all. The piece keeps getting lighter and paler and stops getting smaller. Leather hard is roughly the moment between those two, which is why it is a named stage rather than just a Tuesday.
The water you cannot get out on a shelf
Some of it is not sitting in the clay at all. It is bonded into the mineral, part of the crystal rather than a passenger in it. No amount of shelf time touches that one. Only heat does, somewhere past 660°F, and the moment it leaves, the clay stops being clay. That is the first door.
So why did it crack?
Because a crack is almost never the kiln being cruel. A crack is two parts of the same piece shrinking at different times.
A handle is thin. A mug wall is thick. The handle finishes shrinking days before the wall does, and then the wall carries on shrinking underneath it. Something has to give, and it is always the join. A rim is thin and a base is thick, so that is the same story in a different corner of the same pot.
Which explains why covering a piece works, and why it was never really about keeping it wet. Plastic does not stop a piece drying. It slows the fast parts down so the slow parts can catch up.
The most useful habit in pottery is not a skill. It is even thickness. A piece with the same wall thickness all the way round dries at the same rate all the way round, and a piece that dries evenly mostly survives. Nothing else you learn will save you as many pots.
Wet and plastic
Clay straight out of the bag, or anything you have wet back to that state. Roughly a fifth of its weight is water. Every forming decision you will ever make about a piece happens here, and nowhere else on this page.
How to tell
- A thumb sinks in, and the dent stays where you put it.
- It marks your hands and leaves a film behind.
- Roll a coil and bend it around a finger. Properly plastic clay does not crack along the outside of the curve. If it does, the clay is stiff, tired or short, and it wants wedging or a rest in a bag.
- Cool against your cheek, and it stays that way for as long as it is wet.
Wet and plastic
Water: around 20 percent of its weight.
Window: hours uncovered, weeks in a sealed bag.
Reversible: completely, in both directions.
Costs you: nothing. This is the free stage.
What you do here
- Wedge it first. Wheel or not. Wedging pushes air out, evens the moisture through the block and lines the platelets up. A hand-built slab with air in it splits in the bisque exactly the way a thrown pot does, so this is not a wheel habit.
- Work to an even wall. Same thickness at the rim as at the shoulder, same at the floor as at the wall. If you learn one thing off this page, learn this one.
- Compress the floor and the rim. A rib or a firm finger drawn across the inside floor closes the platelets that opening the clay just pulled apart. Uncompressed floors are where S cracks get written, weeks before anybody sees one.
- Finish the shape before you stop. You cannot open a wall back up tomorrow. Height, width and curve are decided tonight.
- Score and slip every join. Both faces, scored deep enough to feel, then slip or magic water, then press and blend the seam closed on both sides.
- Sponge the standing water out. Water left pooling in a floor keeps softening it long after you have walked away, and a soft floor is a cracked floor.
- Wrap it before you leave. Loose plastic if you want it leather hard by the next session. Tight plastic if you need it to wait for you.
- Scrap goes in the barrel wet. Wet scrap is easy to deal with. The same scrap left drying on a table becomes dust nobody wants to breathe.
What ends a piece here
- Air trapped in the wall. It survives every stage of drying without a hint, holding water long after the rest of the wall has dried, and at bisque temperature that water flashes to steam and takes the piece apart from the inside.
- Too much water. A wall you fought with for twenty minutes is a saturated wall. It slumps, and it will not stiffen evenly afterwards.
- Leaving it uncovered. There is no damp room in this building and there is no humidity in this state. A piece left open on Monday can be past helping by Thursday.
- Uneven thickness. It costs you nothing today. It bills you in nine days.
At The Clay Hole
Plastic sheeting is on us, at every level, so use it on anything you are coming back to. Clay comes from us rather than from outside, and if you need slip for a join, ask whoever is throwing your clay for a scoop out of their throwing water bucket, or make your own from the dried scraps in a clay scrap barrel. Magic water works just as well for most joins.
Reclaiming happens at home, not here. It is a genuinely messy job and a class is not long enough to slake a bucket down, spread it out to stiffen and wedge it back up. Members are welcome to take up to 15 lbs of dried clay home each month out of the barrels, which is free clay if you have the patience for it.
Watch the hands, not the clay
Spiral wedging is the method most people give up on, and almost always for the same reason: they are pushing down and forward instead of down and slightly in, so the spiral never forms. He shows the weight transfer slowly and from the side, which is the angle that makes it click.
If spiral is not working for you yet, ram’s head does the same job with a shallower learning curve. Both methods, ours, are on the wedging page linked at the bottom.
Leather hard
Firm, but nowhere near dry. Around 15 percent of its weight is still water, which is enough to keep the clay workable and not enough to let it deform in your hands. It is the shortest window on this page and the one that decides whether a decent pot becomes a good one.
How to tell
- A fingernail dents it with real effort. A thumb does not.
- It is noticeably darker than the dry parts of the same pot, and still cool on your cheek.
- Turned upside down on the wheel it holds its rim without flattening under trimming pressure.
- A cut with a needle tool comes away clean rather than smearing.
There are two of it
Soft leather hard: a thumbprint still shows if you press. This is the window for attaching handles, joining slabs and anything that has to bond.
Hard leather hard: nothing dents, but a nail still marks it. This is the window for trimming a foot, carving, faceting and burnishing.
Leather hard
Water: around 15 percent of its weight.
Window: often a single day. Sometimes hours in a dry July.
Reversible: yes, slowly and carefully.
Costs you: still nothing. It is the last free stage that lets you change the shape.
What you do here
- Trim the foot. The pot wants to feel like hard cheese. Too soft and the tool tears a furrow; too dry and it chatters, skips and dulls the blade.
- Attach handles, spouts and knobs. Match the stiffness of the part to the stiffness of the pot. A leather hard handle stuck onto a wet mug will shrink first and pull itself off later, and you will blame the kiln.
- Score, slip, press, blend. Score both faces, not one. Slip or magic water. Press until a little squeezes out, then blend that seam flat on both sides of the join.
- Wrap what you just attached. A strip of plastic over a fresh handle slows it down to the pace of the pot underneath it. This one habit prevents most handle cracks.
- Carve, stamp, facet, chatter, sgraffito. All of it wants leather hard. Wet clay smears under a carving tool and bone dry clay crumbles under one.
- Burnish, if you are burnishing. It only takes here. Once the surface goes chalky, no amount of rubbing brings the shine up.
- Underglaze, if you are using it. Underglaze goes on raw clay, at leather hard or bone dry, and gets bisqued before any glaze touches it.
- Sign the bottom. A stamp presses cleanly now. Later you will be trying to carve one into a piece that would rather crumble.
What ends a piece here
- Waiting. The window closes quietly, without announcing itself, and a bone dry pot does not come back to leather hard for you. More work is lost to a busy Tuesday here than to bad technique.
- Trimming through the floor. You cannot see the inside while you cut the outside. Tap the base and listen, or check the thickness with a needle tool before you commit.
- Mismatched stiffness at a join. Two pieces of clay at two different water levels shrink on two different schedules, and the join is what tears.
- Soaking a dry pot to get the window back. Water goes into the outside far faster than it reaches the inside, the outside swells against a core that has not moved, and the pot splits. Wrapping a slightly-too-dry pot in damp cloth inside plastic overnight sometimes works. A dunk in a bucket never does.
At The Clay Hole
Trimming tools carry a colored dot like everything else here, so you can use the ones for your level and every level below it. For joins, magic water and slip both work. There is no slip casting in this building and there never will be, so slip here means glue and nothing else.
What stage is my piece in?
Go and get it. Answer these with the piece actually in your hands and you will know which stage you are looking at, along with what you should be doing about it tonight.
If you put it on the bisque table and it came back to your shelf unglazed, that is once.
This one is the whole trick. Cool means water is still evaporating out of it, and evaporation takes heat with it.
The size you make is not the size you get.
Shrinking starts the moment a piece begins drying and does not finish until the glaze firing is over. Roughly half of it happens on your shelf as the plates close up, and the rest happens in the kilns as the body tightens. Manufacturers publish the two halves added together, which is what the table below carries.
| Clay | Total shrinkage | What that means for you |
|---|---|---|
| 52 Buff | 10% | The least shrinkage of anything we sell, and the most forgiving through drying. |
| B-Mix w/Grog | 11% | The grog opens the body up, which is why it handles thick walls better. |
| B-Mix | 12% | Smooth, and less forgiving for it. Wants even walls and a wrap. |
| B-Mix w/Specks | 12.5% | Wants slow drying, genuinely. Compress rims and floors. |
| Speckled Buff | 12% | Throws better than it looks and behaves normally on a shelf. |
| Half & Half | 12% | Half porcelain, so dry it slowly and dry it evenly. |
| #16 Porcelain | 13.9% | The most on this list. Lids drift out of fit if you are careless. |
| Berlin Gray | 12% | Behaves unusually well through drying for a body this dark. |
Working backwards, with actual arithmetic
Divide the finished size you want by one minus the shrink rate. A 4 inch mug in B-Mix at 12 percent is 4 divided by 0.88, which is 4.55 inches wet. A 10 inch platter in #16 Porcelain at 13.9 percent is 10 divided by 0.861, which is 11.61 inches wet.
Those are averages rather than promises. Wall thickness, how hard you compressed and where a piece sits in the kiln all move the number a little. So if a lid absolutely has to fit a jar, make both from the same bag on the same day and dry them together. The shrinkage calculator does this both ways for every clay we stock.
Can I still save this?
Pick whichever one you are holding. Some of these answers are yes and some are no, and we would rather give you the no now than after you have paid for a firing.
About the scrap barrels. Dry clay you put in a barrel gets used, not binned. Members are welcome to take up to 15 lbs of dried clay home each month and reclaim it at their own table. We do not reclaim inside the studio: it is a genuinely messy job and a class is not long enough to slake a bucket down, spread it out to stiffen and wedge it back up. At home, on your own timeline, it works beautifully and it is free clay.
It cracked. Which stage did it?
Cracks turn up when a piece comes out of a kiln, which is why the kiln gets blamed for them. Nearly all of them were decided weeks earlier, in a stage where the fix would have taken thirty seconds. Pick what you are looking at.
Every crack, traced to its cause
The most useful eleven minutes on this page if you keep losing work and cannot see why. She goes symptom by symptom rather than giving general advice, which is the format this problem actually needs.
The through-line matches ours: almost none of it is the kiln, and almost all of it is compression, thickness and the speed things dried at.
The five stages, the way this studio runs.
The theory on this page is the same everywhere in the world. These parts are ours, and knowing them is the difference between a piece that moves through the building and a piece that sits on your shelf waiting for you to notice something.
The chemistry is the same everywhere. This part is ours.
Wrap it. Every time.
Plastic sheeting is on us at every level. There is no damp room in this building and there is no humidity in this state, so a piece left uncovered on Monday can be past helping by Thursday.
Trim, join, decorate.
Trimming tools carry a colored dot like everything else here, so you can use the ones for your level and every level below it. For joins, magic water or slip. If you want slip, ask whoever is throwing your clay for a scoop from their throwing water bucket.
Sand lightly, clean up fully.
Extremely light sanding at the table is fine. Anything beyond that gets done over a trash can or a clay scrap barrel, and you sweep up whatever made it to the floor before you walk away.
Bisque is free.
Bone dry work goes on the tables marked ready for bisque firing. No ticket, nothing to pay. Our team loads every kiln and fires when the tables fill up, so plan on one to two weeks.
The glaze firing is the paid one.
Pay for it first, write your order number on the kiln ticket with your name, date, clay and glazes, put a cookie under anything that might run, and leave it on the glazeware table. Another one to two weeks, and the kiln cools 24 to 48 hours before anybody is allowed to open it.
Two weeks to collect it.
Two weeks from the day it comes out of the kiln, and after that it is most likely gone. Set yourself a reminder on the day you drop it off rather than trusting future you.
- Wrap everything you are coming back to. Plastic sheeting is free, at every level.
- Bone dry goes on the ready for bisque firing table. No ticket, nothing to pay, one to two weeks.
- The glaze firing is the paid one. Pay first, order number on the kiln ticket, cookie underneath, glazeware table. Another one to two weeks.
- Two weeks to collect it from the day it leaves the kiln. Set the reminder when you drop it off.
One habit that saves more pottery than any other. When you put work on a drop-off table, place it as far left as you can reach without ever touching or moving somebody else’s piece. Every pot on that table is somebody’s six weeks.
The stage questions.
Is greenware the same thing as bone dry?
Not quite, and the difference catches people out. Greenware means any unfired clay piece, so a leather hard pot is greenware too. Bone dry is the specific stage right before the first firing, once everything that can evaporate already has. All bone dry work is greenware. Not all greenware is bone dry.
Where did slip go? I thought that was one of the stages.
Plenty of lists count it, and there is nothing wrong with those lists. We do not, because slip is an ingredient rather than a stage a piece passes through. Nobody makes a pot and waits for it to reach slip. In this building slip means one thing: glue for a join, made from clay and water, and available out of any throwing water bucket. There is no slip casting here and there never will be.
How long does each stage take?
There is no fixed answer and anybody who gives you one is guessing. A small thin piece left uncovered can be bone dry inside 48 hours. A thick sculpture dried properly can take a month or more. Wall thickness, overall size, how well it is wrapped and where it sits on your shelf all move it. The two firings are the predictable part: about one to two weeks each, plus 24 to 48 hours of cooling.
Can I speed drying up?
Evenly, yes. Faster, not really. Anything that dries one part of a piece quicker than another is precisely the thing that cracks it. If a piece has to move along, uncover it gradually and start with the thickest parts, rather than putting the whole thing somewhere warm and hoping.
Why does my piece feel cool when it looks completely dry?
Because evaporation carries heat away with it. A cool piece is a piece that is still losing water, whatever the surface is telling you. Holding it against your cheek is the most reliable check there is, it costs nothing, and it takes a second.
Do I have to wedge if I am only hand-building?
Yes. Wedging is not a wheel thing. It pushes air out, evens the moisture through the block and lines the particles up, and every one of those matters just as much in a slab or a coil pot as it does on a wheel. The three methods are here.
Can I put a wet piece next to a dry one on my shelf?
Perfectly fine, as long as they are not wrapped together under the same plastic. Two pieces sharing a bag share their moisture, which is exactly what you want when you meant it and a problem when you did not.
My piece has sat bone dry for weeks. Is it ruined?
Almost certainly not. Bone dry clay is stable: it is fragile rather than deteriorating, and it will sit there indefinitely without getting any worse. What it will not do is come back to leather hard for you, so if there was trimming or a handle still to do, that ship has sailed.
Does my piece have to go through both firings here?
Both here, or both somewhere else. You are welcome to take bone dry work home and run both firings in your own kiln. What you cannot do is use our free bisque firing and then take the piece away to avoid paying for the glaze firing. The reasoning, in full, is on the firing page.
Why cone 5½ and not just cone 5 or cone 6?
Because a cone measures heat work rather than temperature, which means time at heat counts as much as the number on the controller. Our glaze firing is cone 5 held for twelve minutes, and that hold pushes the total heat work up between cone 5 and cone 6. It gives the glazes time to smooth out and the clay bodies time to tighten, without the slumping risk of pushing the peak higher.
The stages are the map. These fill it in.
Each one of these takes a single stage and goes deeper than a page about all five ever could.
One thing worth taking with you
Three of these five stages will forgive you completely. You can add water, start over, cut the whole thing in half and drop it in a barrel, and nobody will ever know it existed. Only the fire is permanent, and by then the decisions that mattered were made weeks earlier, on a wet Tuesday, with a piece of plastic you either used or did not.
So be bold with wet clay. Be careful about what you send to the kiln. Most people do it exactly the other way round.
Three of these five stages forgive you completely. Only the fire is permanent, and by then the decisions that mattered were made weeks earlier. Be bold with wet clay, and careful about what you send to the kiln.
There is a much longer version of this page: every stage on its own, the physics of why pieces crack, a crack tracer, the shrinkage table and seven more videos. The toggle at the top switches to it.
Still not sure what stage your piece is in? Bring it to class and ask anyone in a bright pink shirt. Working that out at a glance is a large part of what they are there for, and they would far rather look at it before you fire it than after. You can also text us on 385-241-5528 during class hours.
Not a member yet? Everything on this page happens on a shelf with your name on it.