The Clay Hole guide to opening

Opening the clay, and setting a floor you can live with

Centering gets all the attention. Opening is where the pot actually gets decided. Four seconds of pushing down and you have already locked in how deep it is, how wide it is, how much clay is under there, and whether it cracks in the drying rack three weeks from now.

Nobody can fix a floor from above. So this page is about getting it right on the way down.

Take me to the steps Just the phone list
A potter pressing both thumbs down into a centered lump of clay to open the base of a pot on a spinning pottery wheel
Take me to the steps Just the phone list
x8 videos from potters who are not us, every one credited and linked
x4 ways to open a lump, and all four of them are correct
x1 measurement that decides the pot, taken before you pull anything
x6 steps, in the order your hands do them
1/4 of an inch of floor, which is the number this whole page exists for
x2 videos, eleven minutes together, from potters who are not us

Everything we know about opening a pot and setting its floor, in order.

Start here

The whole idea, in one sentence.

You are not digging a hole. You are moving a fixed amount of clay out of the middle and parking it in a ring around the outside, where it becomes your walls. Nothing is added and nothing is removed. You are only deciding where it sits, and how much stays underneath.

How much stays underneath is the whole job.

The number you are aiming for

A quarter inch of floor. That is the working answer for almost everything you will make on a normal evening. The real rule underneath it is that the floor should match the thickness of your wall, plus another quarter inch if you plan to trim a foot ring into it, and plates want a half to five eighths.

Everything on this page, in order

01 · Read it, then watch it

Why this page is a wall of words with videos stuck in it

One more thing before you scroll

Nothing on this page is a rule handed down from a mountain. Potters disagree about opening more than they disagree about almost anything else on the wheel, and half the arguments come down to hand size. Where two good methods contradict each other, I have said so instead of picking a winner and pretending.

I could have just made you a playlist.

It would have taken me an afternoon instead of a week, and it would have been eight excellent videos from eight people who open clay better than I do. You would have watched all eight in a row, felt fantastic about yourself, sat down at a wheel, and pushed your thumb clean through the bottom of a two pound lump.

I know that because I have done it. More than once. With good clay.

Here is what I think is happening, and I am not going to pretend I have a laboratory. Watching somebody good is smooth. Every move they make looks obvious while they are making it, and your brain reads that smoothness as understanding. It feels exactly like learning feels. Then you sit down and your hands find out that you collected a feeling instead of a procedure.

Reading is worse. That is the point.

Reading is slower and clunkier and you have to build the picture yourself, which is irritating, and which is also the entire mechanism. When a sentence tells you to leave a quarter inch under there, you have to stop and imagine a quarter inch of clay, and your hands get dragged into imagining it with you. Nobody watches a video and imagines a quarter inch. They just watch somebody else have one.

So here is the deal I am proposing.

Read the steps once. Watch a real potter do it. Then read the steps again with your phone leaned against the splash pan, hands filthy, wheel spinning. That third pass is the one that sticks, and it is the reason every list on this page is short enough to fit on a phone without scrolling.

Videos show you what it looks like. Words tell you what to check. You want both, and you want them in that order.

02 · The shape under your hands

What opening is, and where the clay actually goes

Opening is not digging a hole. It is moving a fixed amount of clay out of the middle and parking it in a ring around the outside, where it becomes your walls. Nothing is added. Nothing is removed. You are only deciding where it sits.

Cross section of a lump of clay after opening A cut-through view of centered clay opened on a bat, with six numbered markers pointing at the floor, the inside corner, the wall stub, the opening width, the outer base width, and the bat. 1 2 3 4 5 6
  1. The floor. Everything between the inside surface and the bat. This is the number the rest of the page keeps coming back to, and the only part of the pot you cannot fix later from the inside.
  2. The inside corner. The little valley where the floor meets the wall. Clay hides in there, and a lump left sitting in that corner never joins the wall no matter how many times you pull.
  3. The wall stub. The ring of clay you just pushed outward. It is short and fat right now, and it is the entire supply for every wall you are about to pull. Whatever is not in this ring is not coming.
  4. The opening width. The inside diameter of the well. This one quietly decides whether you are making a cylinder or a bowl, before you have touched a wall.
  5. The outer base. The footprint on the bat. Your finished pot cannot have a base narrower than this without collaring, so open with the finished pot in mind.
  6. The bat or wheel head. The thing your needle tool stops against, which is what makes the measurement in section 05 possible at all.

The rule, in one sentence

The floor should be about as thick as the bottom of your wall, plus another quarter inch if you plan to trim a foot ring into it. That is the whole rule. Everything else on this page is about how to actually hit it.

Why a foot ring changes the number

A foot ring is a groove you cut out of the floor after the pot dries. If you did not leave the extra quarter inch, you are cutting that groove out of clay the pot needed, and the last step of a good pot becomes a hole. Plates want more still, somewhere around a half to five eighths of an inch.

03 · The move itself

Opening, step by step, on any wheel, with any hands

Six steps, in the order your hands do them

This is the sequence underneath all four methods further down. The hand shape changes. The order never does.

Whatever you do with your fingers, this is the order. Braced arms, slow wheel, straight down, stop early, measure, compress.

  1. 01

    Slow the wheel down

    You centered fast. Open slower. Fast clay grabs whatever you put into it and drags it outward, and outward is the one direction you do not want yet. Somewhere around half your centering speed is right. Not stopped, and not crawling either, because a slow wheel will happily follow your finger off center.

  2. 02

    Wet your hands, then brace them

    Dry hands tear. Soaking hands slip. Wet, then shake once. Now anchor your arms: elbows into your thighs, or a forearm on the splash pan rim, or a wrist locked against the pan edge. Your arms are a tripod, not two independent robots. Almost every off center opening I have watched started with somebody holding their hands in midair.

  3. 03

    Find the true center while it spins

    Rest one fingertip lightly on top of the spinning lump and drift it toward the middle. When the fingertip stops making a ring and starts making a single still dot, that is your center. Trust the dot, not your eyes. Your eyes will insist the center is wherever you happen to be looking from.

  4. 04

    Press straight down, slowly, and do not chase

    Straight down. Not down and forward, not down and toward you, and no wandering while you look for the middle. Ease in over a few seconds rather than committing all at once. If it starts pulling off center, do not chase it around: lift off, re-anchor, put the dot back, and go again.

  5. 05

    Stop earlier than feels right

    This is the whole ballgame and it takes about two seconds of restraint. You can always take more clay out of a floor. You can never put it back, and there is no move in throwing that reaches into a wall and drags clay back down into the bottom. Stop high, measure, and go deeper if the number says so.

  6. 06

    Measure it now, with a needle tool

    Sponge the puddle out first, because water in the bottom makes every depth look identical. Then needle straight down until it stops on the bat, pinch it where it leaves the clay, lift, and look. Four seconds, and it is the highest value four seconds in throwing, entirely because of when you do it. Section 05 has the full version.

  7. 07

    Compress the floor

    Several firm passes from the middle outward with a rib or a flat fingertip, right now, while it is still wet and flat and easy to reach. Eight seconds. Section 06 explains why skipping it hands you a cracked pot three weeks later, long after you have forgotten what you did wrong.

  8. 08

    Widen to the base you actually want

    Fingers in the bottom of the well, pull steadily toward yourself, and open out until the inside floor is the width of the base of your finished pot. Go in stages rather than one heroic sweep. Keep the floor flat while you do it, because a floor that domes in the middle stays domed forever.

  9. 09

    Clean out the inside corner

    Run a finger firmly into the valley where the floor meets the wall and drag it out and up. That is the last thing you do before your first pull, and it is the single most common reason a beginner ends up with a short pot and a heavy bottom. The clay was there the whole time. It just never got invited into the wall.

  1. 01

    Slow the wheel down and brace your arms

    Roughly half your centering speed. Then anchor: elbows into your thighs, or a wrist locked against the splash pan. Almost every opening that wanders off center started with somebody holding their hands in midair. Wet hands, then shake once, because dry hands tear and soaking hands slip.

  2. 02

    Find the true center with a fingertip

    Rest one fingertip lightly on the spinning lump and drift it inward. When it stops making a ring and starts making a single still dot, that is your center. Trust the dot, not your eyes. Your eyes sit off to one side of the wheel and will lie to you about where the middle is.

  3. 03

    Press straight down, slowly, and stop early

    Straight down. Not down and forward, no wandering. Ease in over a few seconds. Then stop sooner than feels right, because you can always take more clay out of a floor and there is no move in throwing that puts it back. If it starts pulling off center, lift off, re-anchor, find the dot, and go again rather than chasing it around.

  4. 04

    Sponge the water out and measure with a needle tool

    The puddle in the bottom makes every depth look identical, so take it out first. Then push a needle straight down, slightly off center, until it stops on the bat. Pinch it where it leaves the clay, lift, and look at the wet length. Aim for a quarter inch. Close the pinhole behind you with one pass of a fingertip, every time. Wrap tape around the needle a quarter inch up and the tool answers the question for you.

  5. 05

    Compress the floor

    Three or four firm passes with a rib or a flat fingertip, from the middle outward, while the wheel turns. Eight seconds. This is the step that decides whether the bottom cracks in the drying rack three weeks from now, and it is the one people skip, because skipping it costs nothing until it costs you the pot.

  6. 06

    Widen to the base you want, then clean the corner

    Fingers in the bottom of the well, pull steadily toward yourself in two or three passes until the floor is as wide as the base of the pot in your head. Walls grow straight up out of that edge, so this is where you choose between a mug and a bowl. Compress once more, then drag a finger firmly out of the valley where the floor meets the wall. Clay hides in that corner, and a lump left sitting there never joins the wall no matter how many times you pull.

Watch this one all the way through

How to Open Up Centred Clay and Form the Base of a Pot — A Beginner’s Guide

Florian Gadsby · about 15 minutes

Fifteen unhurried minutes on a motion that takes four seconds, which is exactly the ratio a beginner needs. He measures with a needle tool at the moment the answer is still useful, compresses on camera, and says out loud what his hands are doing while they do it. If you only watch one video on this page, watch this one, and then watch it again after you have opened five lumps yourself. It is a completely different video the second time.

Nothing loads from YouTube until you press play. Watch on YouTube

A second pair of hands, slower

Opening your clay After you center for beginners

Earth Nation Ceramics · about 9 minutes

A different body, a different wheel, and a different set of hands doing the same job, which is the reason to watch a second one at all. Pay attention to what his arms are doing rather than his fingers. The bracing is the lesson.

Nothing loads from YouTube until you press play. Watch on YouTube

04 · Four ways in

Four ways to open, and all four of them are correct

This is where the internet argues, and the argument is mostly about hand size and lump size rather than about right and wrong. Try all four across one evening. One of them will feel like it was built for you, and that is the one you keep.

Method one

Both thumbs

Hands wrap the outside of the lump, fingers laced or touching, and both thumbs press down together in the middle. The two thumbs brace each other, so there is very little for the clay to push sideways.

  • Best for small and medium lumps, and for anybody whose hands shake on their first ten pots.
  • Why it works your hands form a closed ring, so the lump cannot escape the ring even when your pressure is uneven.
  • Watch out for thumbs that drift apart as you go down, which opens a wide sloppy well before you have any depth.

Method two

One thumb, braced

One thumb does the pressing. The other hand wraps over the back of that hand or clamps the wrist, and does nothing but hold it still. The working thumb becomes a drill bit mounted in a machine rather than a thumb on the end of an arm.

  • Best for people who find two thumbs cramped, and for narrow openings on tall forms.
  • Why it works one point of contact is far easier to keep in the exact center than two.
  • Watch out for the bracing hand quietly starting to help, which is how the hole ends up leaning.

Method three

Two fingers, braced

Index and middle finger of the dominant hand, held together, pressing down. The other hand cups the outside of the lump or locks over the working hand. Most production potters you watch on the internet are doing some version of this.

  • Best for larger lumps, and for opening and widening in one continuous motion.
  • Why it works fingers reach deeper than thumbs and stay strong at the bottom of a tall well.
  • Watch out for fingertips, which are narrower than thumbs and dig faster than you expect. Ease in.

Method four

The heel or the fist

On a big lump, the heel of your hand or a loose fist goes down into the middle and the sheer surface area does the work. Less precise, far less tiring, and the only one of the four that does not leave your wrist complaining after ten pounds.

  • Best for anything over about five pounds, and for opening wide, shallow forms like plates and platters.
  • Why it works body weight beats finger strength once the lump gets big.
  • Watch out for depth. A wide tool makes a wide flat well fast, and the bottom arrives sooner than it feels like it should.

The part all four share

Braced arms, slow wheel, straight down, stop early, measure. If a method you invented yourself has those five things in it, it is a real method and you should keep using it. If it does not, no amount of hand position is going to save it.

A note on which hand

Nearly every video on this page is thrown on a counterclockwise wheel, which is the usual setting for most throwers. Your bracing hand generally sits on the side the clay is arriving from, so the lump runs into a wall instead of running away from you. Throwing clockwise instead? Everything here still applies with left and right swapped.

05 · Depth

The measurement that decides the pot

Nobody can see a floor. You can feel one and you can measure one, and in the entire history of pottery those have been the only two options. Looking into a wet pot tells you nothing at all, because there is water sitting in the bottom making every depth look like the same depth. That puddle has ended more mugs than bad centering has.

What you are makingFloor you are aiming forBecause
Flat bottom, nothing trimmed Same as the bottom of your wall Even thickness dries evenly, and nothing is going to be cut away later
Trimming a foot ring Wall thickness plus about a quarter inch The foot ring is a groove cut out of that floor, so it has to come from somewhere
Mugs, cups, most first pots About a quarter inch Most walls land near three sixteenths, and most mugs get some kind of trim
Plates and platters About a half to five eighths A wide unsupported floor has to survive drying, a kiln shelf, and a dinner table
A small dish you will never trim Three sixteenths is fine Nothing is being removed and nothing is being carried

These are wet numbers, measured on the wheel before anything dries or shrinks. The full set of throwing ratios lives on our throwing by the numbers page.

How to actually check it, in four steps

  1. 01

    Sponge the water out

    Ten seconds with a sponge on a stick. You cannot judge, feel or measure a floor you cannot actually touch.

  2. 02

    Needle straight down, slightly off center

    Push until it stops on the bat. Off center on purpose, so the hole you just made is not sitting at the exact spot a crack would most like to begin.

  3. 03

    Pinch, lift, look

    Thumbnail against the clay surface, pull the needle out, and look at the wet length below your nail. That is your floor, in real units, instead of a feeling and a hope.

  4. 04

    Close the hole behind you

    One pass with a fingertip or a rib and it is gone. Do this every single time. A pinhole left in a floor is a leak in a finished mug.

Put a piece of tape on your needle tool

Wrap a scrap of tape around the needle a quarter inch up from the point. Now the tool tells you the answer instead of your judgment telling you the answer, and you never have to have this argument with yourself again at eight in the evening with tired hands.

The fingertip test, for later

Stop the wheel and press the middle of the floor with a fingertip. A good floor feels like a table. A thin one gives. Once you have felt the difference two or three times you will only need the needle to confirm what your finger already told you.

Put a piece of tape on your needle tool

Wrap a scrap of tape around the needle a quarter inch up from the point. Now the tool tells you the answer instead of your judgment telling you the answer, and you never have to have that argument with yourself again at eight in the evening with tired hands.

Sixty seconds, one skill

How to Measure Base Thickness

Harley Weigle Studio · about 1 minute

The needle tool measurement, done properly, in about a minute. Short enough that you can watch it on your phone, put the phone down, and do it immediately while the picture is still in your head. That is the whole reason it is here instead of a longer one.

Nothing loads from YouTube until you press play. Watch on YouTube

06 · Compression

Eight seconds now, or a crack in three weeks

The why, from people who study it

Stop S Cracks for Good with Dr Clay and Katie — Align, Compress, Prevent

The Clay CoOp · about 6 minutes

Most compression advice is one sentence long and then everybody moves on. This one goes into what the particles are actually doing and why alignment matters, which is the difference between following a rule and understanding one. Understanding it is what makes you do it on the night you are tired.

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Here is the part that feels optional and is not.

When you push down and out, you drag the clay particles in the floor outward with you. They end up fanned out and loosely stacked, a bit like a deck of cards somebody smeared across a table. The pot looks perfect. It is perfect, today.

Then it dries, and drying means shrinking, and a fanned out floor shrinks unevenly against a wall that is packed tight. Something has to give, and what gives is the middle of your floor, in a lazy S shaped line, usually after it comes out of the bisque firing.

That is an S crack, and nobody has ever fixed one.

The prevention costs eight seconds. Immediately after you open, run a rib or a firm flat fingertip across the floor from the middle outward, several times, while the wheel turns. You are stacking those particles back down into a tight even layer. Then do it once more after you widen, because widening fans them out again.

That is it. That is the whole technique. It is the highest return eight seconds in the entire process, and it is the one people skip most, because skipping it costs you nothing for about three weeks.

A rib or a finger

Either works. A wooden or metal rib with a flat edge gives you a flatter floor and more even pressure. A fingertip gives you better feedback about what is actually happening down there. Beginners should use a finger until the feel is familiar, then switch to a rib for the flatness.

Middle outward, every time

Start at the center and travel out to the corner. Going the other direction pushes clay into the middle and can leave you a small dome, which is the one shape a floor should never be. Three or four firm passes, not twenty timid ones.

Do it twice

Once right after you open, once right after you widen. If you are making something wide and flat like a plate, do it again before you finish, because a big floor has more room to loosen up and more surface area to crack across.

07 · Width

How wide to open, and why that is already the shape

Depth gets all the worry and width gets almost none, which is backwards. Depth decides whether the pot survives. Width decides what the pot is. By the time you have widened the floor you have chosen between a mug and a bowl, and pulling walls will not change your mind for you.

The rule is short: open the floor to the width of the base of the pot you want. Not close to it. That width.

Walls grow straight up out of the edge of the floor. If your floor is two inches across, you are getting a two inch base, and the only way to a wider pot from there is to belly it out later, which costs clay and thickness and patience. If your floor is five inches across, you have a bowl, and no amount of collaring is going to turn it back into a mug without a fight.

So before your hands go in, answer one question. How wide is the bottom of the thing in your head?

Then open to that, and stop.

Widen in stages

Fingers into the bottom of the well, steady pull toward yourself, then out. Do it in two or three passes instead of one long confident sweep. A single sweep is how a floor ends up thinner on one side than the other, and you will not find out until you are trimming.

Keep it flat, not dished

Fingers naturally scoop, which leaves the middle of the floor higher than the corner or lower than the corner depending on your grip. Neither is what you want on a cylinder. Flatten it with a rib after you widen and check it by eye with the wheel stopped.

Leave the outside alone

Widening is an inside job. The outer footprint on the bat should barely move. If the outside of your lump is spreading across the bat while you widen, you are pushing down and out instead of out, and the pot is getting shorter every second.

A working potter disagrees with the cautious version

The reason I open my bases so wide

Amy Palatnick · about 30 seconds

Half a minute, and it is here because it argues with the careful advice above it. Plenty of excellent potters open much wider than a beginner would dare and then bring the form in as they pull. Watch it, understand why she does it, and then decide for yourself which one you want to be. That is a better outcome than agreeing with me.

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08 · Shape by shape

What you are making changes how you open it

Same nine steps every time. Different numbers. Tap whichever one you are actually sitting down to make.

Mug or cup

Floor
About a quarter inch, because almost every mug gets a foot trimmed into it
Opening width
Roughly the width of the base you want, which for most mugs is somewhere near three inches
Floor shape
Flat. A dished mug bottom holds coffee grounds and a domed one wobbles
The thing people miss
The inside corner. A mug is short enough that a lump left in the corner never gets pulled out, and you end up with a heavy little pot that feels like a brick in the hand

Bowl

Floor
A quarter inch at least, and thicker on anything over about eight inches across
Opening width
Narrower than you think. A bowl gets its width from the curve of the wall, not from a wide floor
Floor shape
Gently curved into the wall rather than a hard corner, so the inside reads as one continuous sweep
The thing people miss
Opening too wide at the start. Once the floor is five inches across, the bowl you get is the bowl you get, and it will be shallow

Plate or platter

Floor
About a half to five eighths of an inch, and no arguing about it
Opening width
Nearly the whole lump. Open with the heel of your hand and go wide early
Floor shape
Dead flat, checked with a straight rib laid across it while the wheel is stopped
The thing people miss
Compression. A wide flat floor is the most crack prone thing you can make, so compress after opening, after widening, and once more before you finish

Vase or anything tall

Floor
A quarter inch, and be stricter about it than usual, because a tall pot puts more weight on its own bottom
Opening width
Narrow. Narrower than feels useful. A tall form wants a small footprint and a lot of wall
Floor shape
Flat, with a clean sharp inside corner so the wall has something to grow out of
The thing people miss
Reaching. A narrow well is hard to measure and hard to compress once it is deep, so do both before you widen anything, while your hand still fits

Bowls and cylinders, part one

Opening Bowls vs Cylinders Part 1

Twisted Clay

The clearest short demonstration of the point section 07 is making: the shape of the pot is decided down here, not up in the walls.

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Bowls and cylinders, part two

Opening Bowls vs Cylinders Part 2

Twisted Clay · about 1 minute

The follow up, and the half that shows what the difference costs you later if you get it backwards. Watch both, in order, in under three minutes total.

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09 · Diagnosis

Nine ways opening goes wrong, and what to do about each

Three things that go wrong on a first night

Tap whatever just happened. Every one of these has happened to me, most of them in front of other people.

Tap whatever just happened. All three have happened to me, and all three come from the same two seconds of not stopping.

The hole is not in the middle

What happened. You went down where you were looking instead of where the clay was actually spinning. Your eyes sit off to one side of the wheel, so the visual center and the real center are never the same point.

Right now. If the walls are still thick, you can often save it. Slow the wheel, put a fingertip on the spinning surface to find the true dot, and open a second time from there, letting the new well swallow the old one. If the wall is already thin on one side, wire it off and start over. It is two minutes of clay and twenty minutes of frustration.

Next time. Find the still dot with a fingertip before you commit any pressure. Every time. It takes one second.

It went off center while I was pushing

What happened. Almost always unbraced arms, and almost always at speed. Your hand had nothing to push against except the clay, so the clay won. The second most common cause is pressing down and forward instead of straight down.

Right now. Do not chase it around the wheel. Lift off completely, slow down, re-anchor your elbows against your legs, find the dot again, and go back in gently. Chasing a wandering hole is how a good lump becomes a wobbling mess in about four seconds.

Next time. Elbows locked into your thighs before your hands touch anything, and open at roughly half the speed you centered at.

I went through the bottom

What happened. You did not stop early and you did not measure. That is the whole story, and everybody gets this one, usually more than once.

Right now. Wire it off and wedge it up. There is no honest patch for a hole in a wet floor. A plug of clay pressed into it will look fine on the wheel and will come apart at some point between the drying rack and the kiln, and you will not know which pot in the load is going to fail.

Next time. Tape on the needle tool, and treat step five as a rule instead of a suggestion. Stop shallow, measure, then go deeper if the number says you can.

The pot is short and it feels heavy

What happened. The clay never made it up. It is sitting in the floor, or in the inside corner, or in both, and no number of pulls will find it because pulls only move what is already in the wall.

Right now. If it is still wet, get a finger into the inside corner and drag that clay out and up before your next pull. That alone can add a surprising amount of height. If it is the floor that is too thick, trimming can take some of it back later, though you will be trimming a lot.

Next time. Clean the corner as step nine, every single time, before pull one.

There is a dome in the middle of the floor

What happened. You compressed from the outside toward the middle, or you widened by scooping, and clay piled up in the center. A dome is also what you get when the wheel head has a bump on it and you never noticed.

Right now. Flatten it with a rib, working center to corner, while the wheel turns slowly. Check it with the wheel stopped by laying a straight edge across it.

Next time. Every compression pass and every widening pass travels from the middle outward. Never the other way.

A crack appeared in the bottom weeks later

What happened. Almost certainly an S crack, and almost certainly no compression, or not enough of it. It shows up after drying or after the bisque firing, which is a cruel amount of delay between the mistake and the news.

Right now. Nothing. This is the honest answer and I am not going to dress it up. A fired S crack is not repairable in any way that produces a piece you would want to drink out of.

Next time. Compress after opening and again after widening. Also slow the drying down, because a floor stuck to a bat dries slower than a wall in open air, and that difference is what pulls the crack open.

There is a ridge or a lump in the inside corner

What happened. Your fingers rounded off before they reached the corner, so a wedge of clay got left standing in the valley. It is the most common thing a beginner cannot see, because you are looking down into a wet pot at the one spot the light does not reach.

Right now. Wheel turning slowly, finger pressed firmly into the corner, drag out and then up. You should feel the ridge give way. Sponge the water out first so you can actually feel what you are touching.

Next time. Make cleaning the corner its own deliberate step rather than something that happens on the way to something else.

The top tore open into a wide crater

What happened. Too much speed, too much sideways pressure, too early. The top of the lump is the least supported part of it, so it spreads first and it spreads fast.

Right now. If the crater is shallow, collar the top back in with both hands and carry on. If the rim is torn and ragged, cut it off level with a needle tool and accept a shorter pot.

Next time. Get your depth first, then widen. Trying to do both at once is what tears rims.

One side of the wall is thicker than the other

What happened. The well is off center even though the outside of the lump looks fine. This is the sneaky version of problem one, and it usually only announces itself when your first pull comes up thin on one side and fat on the other.

Right now. With thick walls you can sometimes re-center the inside by opening again from the true dot. Once the wall is thin, it is done. Wire it and move on with your evening.

Next time. After you open, rest a fingertip inside the well against the wall with the wheel spinning. An off center well beats against your finger once per rotation. You will feel it long before you can see it.

The most common failure, on camera

How to Avoid Pushing Your Clay Off Center, Part 1

Twisted Clay · about 3 minutes

Problems one, two and nine on this list are all the same problem wearing different hats, and this is three minutes on exactly that. Worth watching before your next session rather than after your next disaster.

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10 · The short version

The list to keep on your phone

Everything above, in eleven lines, sized to fit a phone screen without scrolling. Prop it against the splash pan and stop reading the rest of this page.

If you only remember three of them, remember stop early, measure, and compress. Those three prevent most of the ways this goes wrong, and the other eight are just how you make them easy.

You are reading the Nutshell Version. The switch at the top opens the comprehensive one, which covers four ways to open, how wide to go for each shape, and nine ways it goes wrong.

  1. Slow the wheel to about half your centering speed.
  2. Wet hands, then brace: elbows on thighs, wrist on the pan.
  3. Fingertip on top until the ring becomes one still dot.
  4. Press straight down. Slowly. Do not chase it.
  5. Stop early. You can take more. You can never add.
  6. Sponge the water out.
  7. Needle down to the bat, pinch, lift, look. Close the hole.
  8. Aim for a quarter inch, or wall thickness plus a quarter if you are trimming a foot.
  9. Compress: rib or finger, middle outward, several firm passes.
  10. Widen in stages to the base width you actually want, then compress again.
  11. Drag a finger out of the inside corner. Now pull.

11 · Practice, then keep going

Where to go next

Three drills that are worth more than another hour of video

Open five, throw none

One evening. Five lumps, all the same weight. Center, open, measure, write the number down, wire it off, wedge it up, do it again. No walls, no pots, no pressure. By the fifth one your hand knows what a quarter inch feels like, and you have learned more than five finished mugs would have taught you.

Cut one in half

Take a pot you are happy with, run a wire down through it from rim to base, stand the two halves up, and look at the cross section. You will find out how thick your floor actually is, where you left clay behind, and how much heavier the bottom is than you believed. Nobody has ever done this and been unsurprised.

Tape the tool

Not really a drill, more a thirty second decision. Wrap tape around your needle tool a quarter inch from the point and leave it there for a month. You will stop guessing, and after a month of not guessing you will not need the tape, because your hand will have quietly learned the distance.

Where to go next

Opening sits in the middle of a sequence. Here is what is on either side of it, and the pages that go deeper on the parts this one only touched.

Comes before this How to center clay None of this works on a lump that is not centered. Start here if the dot never sits still. Comes before this Struggling to cone Coning is how the clay gets aligned and even before you ever push down into it. Comes after this How to pull walls The next four minutes of the same pot, and the only thing your wall stub is for. Goes deeper Throwing by the numbers Every measurement in throwing, including where the floor numbers on this page came from. When it went wrong Fixing a floor thrown too thin Four moments you can catch a thin floor, and what is actually possible at each one. Free tool Tap centering practice A practice wheel that runs in your browser, for the day you trim the pot you just opened. Related How to stop pots twisting Torque, and the five places it creeps into a pot that was fine a second ago. The whole thing How to throw on the wheel The full guide this page is one chapter of, start to finish, written to be read.

One last honest thing

You are going to read all of this, agree with all of it, sit down, and push straight through the bottom anyway. Probably twice.

That is not a failure of the page and it is not a failure of you. It is what learning a physical thing looks like from the inside. The words give your hands something to aim at, and then your hands take a few weeks to catch up, and one evening you will open a lump without thinking about any of this and it will just be a quarter inch, because it always is now.

That evening is closer than it feels tonight.

Throw with us in Draper

Twenty nine wheels, four kilns, and instructors who will stand behind you and tell you when to stop pushing. Membership starts at $145 a month.