Five stages. Four of them will forgive you.
Clay is the same material from the bag to the shelf. The only thing that really changes is how much water is left in it, and that one number decides what you can do to your piece, what you can still fix, and what you have permanently lost.
Here is all five stages, how to tell which one your piece is in right now, and the exact moment it stops being reversible.
Four stages are a loop. The fifth is a door.
Slip, plastic, leather-hard and bone dry are not four different materials. They are the same clay holding four different amounts of water. Add water and you move backwards. Take water away and you move forwards. Nothing has been decided yet.
Then the kiln.
Somewhere past 660°F, the water that is chemically locked inside the clay itself gets driven out of it. Unlike every drop before it, that water does not come back. The particles fuse. What comes out of that first firing is ceramic, and ceramic will never soften in water again. Not in a bucket, not in a lifetime, not if you leave it in the sink until Christmas.
That is the whole map. Four stages where every mistake is free, and one door at the end of the hall.
It is worth sitting with, because most people have it backwards. New potters are precious with wet clay and casual about the kiln, when wet clay is the most forgiving material in this building and the kiln is the least forgiving thing we own.
The practical version. A piece you hate at any point before it goes in for its bisque firing has cost you nothing but time. A piece you hate after that is a piece you own.
What your clay is actually doing.
Tap a stage. Each one tells you what it feels like, what it will let you get away with, what it will not, and what tends to kill a piece right there.
Slip
Clay and water mixed until it pours. Somewhere between heavy cream and gravy, depending on what you need it for.
We do not slip cast here and we never will, so slip in this building means one thing: glue. For attaching a handle, magic water or slip both work well. If you want slip, ask somebody throwing your clay for a scoop out of their throwing water bucket, or make your own from dried scraps out of the clay scrap barrels. The Clay Mender on the shelf is not the tool for this job.
Bone dry and bisque look almost identical sitting on a shelf. Weight and a fingernail tell them apart, and so does the tape on the shelf they came back on.
Drying is the part that breaks things.
There are three kinds of water in a piece of clay and they leave at three different times. Once you know that, nearly every crack in this building explains itself.
First, the water holding the particles apart. Wet clay is millions of tiny flat plates with water between them, which is the entire reason it slides into a shape instead of crumbling into one. As that water evaporates the plates slide closer together and the piece gets physically smaller. That is your shrinkage. It is also where nearly every crack comes from.
Then, the water in the gaps. Eventually the plates are touching and cannot get any 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.
And then the water you cannot get out. Some of it is bonded into the clay chemically, part of the mineral rather than sitting inside it. No amount of shelf time touches that one. Only heat does, somewhere past 660°F, and that is the door we were talking about.
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.
What stage is my piece in?
Go and get it. Answer these with the piece in your hands and you will know, along with what you should be doing with it tonight.
If you put it on the bisque table and it came back to your shelf, that is a yes.
This one is the whole trick. Cool means water is still evaporating out of it, and evaporation takes heat with it.
Answer the questions above and your piece gets identified here, along with what to do with it.
The size you make is not the size you get.
Every clay we carry loses somewhere between a tenth and a seventh of its size between the wet lump and the finished object. It is the most common surprise a new member gets, and it is entirely predictable.
Make it this big instead.
Works for any single measurement: a width, a height, or the diameter of a lid.
Make it 4.55 inches and it should come out of the glaze firing at about 4 inches.
Shrinking starts the moment a piece starts drying and it does not finish until the glaze firing is over. Clay manufacturers publish the two halves added together, and that combined figure is what is on the cards above.
Those are averages rather than promises. Wall thickness, how hard you compressed, and where a piece happens to sit in the kiln all move the number a little. So if a lid absolutely has to fit a jar, make the lid and the jar from the same bag on the same day, and dry them together.
All eight clays, what each one is good at, and the full calculator (opens in a new tab) live on the clay page.
Can I still save this?
Pick whichever one you are holding. Some of these answers are yes, some are no, and we would rather give you the no now than after you have paid for a firing.
Pick one above for a straight answer.
About the scrap barrels. Dry clay you put in a barrel does not get thrown away, it gets used. Members are welcome to take up to 15 lbs of dried clay home each month from the barrels and reclaim it at their own table.
We do not allow reclaiming 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.
Pick a symptom above and we will trace it back to the stage that caused it.
The five stages, the way this studio runs.
The theory is the same everywhere. These are the parts that are specific to us.
Wrap it. Every time.
The plastic sheeting is on us, so use it on anything you are coming back to. There is no damp room in this building and there is no humidity in this state. A piece you leave uncovered on Monday can be past helping by Thursday.
Trim, join, decorate.
Trimming tools carry a color mark like everything else here, so your level and every level below it. For joins, magic water or slip. If you want slip, ask somebody 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 they fire when the tables fill up. Plan on one to two weeks.
The glaze firing is the paid one.
Pay for it first, write your order number on your kiln ticket, put a cookie under the piece 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.
Come and get it.
You have two weeks from the day it comes out of the kiln. After that it is most likely gone, so set yourself a reminder on the day you drop it off rather than trusting future you.
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.
Kiln firing prices, the measuring rules and the full drop-off process (opens in a new tab) are on the firing page.
Clay gives you a deadline you cannot argue with.
Here is the thing about clay that nobody warns you about.
Every other material waits for you. Wood waits. Paint waits. A canvas will sit in a garage for a decade and be exactly as ready as the day it was bought.
Clay does not wait.
Clay is on a schedule, and that schedule started the second you opened the bag. You get a few hours to make the thing. You get a day or so, give or take, to trim it and put a handle on it. Then the window closes, quietly, without announcing itself, and the piece decides for itself what it is going to be.
I have lost a lot of work to that window. Not to bad technique. To a Tuesday.
I got busy. Or I got tired. Or I told myself I would come back Thursday and do the foot, and then Thursday showed up and the piece was bone dry and the foot was never happening.
Which is annoying.
But here is the part I actually want to say, and it is my favorite thing to teach in this entire building.
Four of these five stages will forgive you completely.
You can add water. You can start over. You can cut the whole ridiculous thing in half, drop it in the barrel, and no human being will ever know it existed.
Only the fire is permanent.
I think about that more than a pottery lesson probably warrants. Most of what I have gotten wrong turned out to be recoverable, and I almost never knew it at the time. I sat there absolutely certain a thing was ruined when it was only leather-hard.
Anyway.
Wrap your work in plastic.
That is the actual lesson.
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.
How long does each stage take?
There is no fixed answer, and anyone 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.
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, and it costs nothing and 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. (opens in a new tab)
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, not 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. (opens in a new tab)
The stages are the map. These fill it in.
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 genuinely rather look at it before you fire it than after.
Or text us on 385-241-5528 and we will answer during class hours.
Not a member yet? Everything on this page happens on a shelf with your name on it.