Project guides

Making Smokeware and Water Vessels

A popular thing to make and an easy thing to make badly. These are the only pots most people own that get an open flame held against them, so the glaze decisions matter more than usual, the airway has to survive shrinkage, and a water chamber has to actually be watertight. Here is what changes when a pot has a job like this one.

Leave the bowl unglazed, build the airway oversized because it shrinks, vent every hollow chamber so it does not explode, and make sure you can clean it. Check studio policy before you start.

Glaze, heat and what to avoid Airways, chambers and shrinkage Two videos, none of them ours
The rules that matter Building it Three things that go wrong
An illustration of two potters in a studio, one shaping a gray clay water vessel on a turntable while the other laughs beside a finished green glazed one
Jump to a section
Before you start Glaze, heat and the bowl The airway Building a dry piece Water chambers and downstems Cleaning, and why it decides the design What goes wrong The whole idea, quickly Building it Three things that go wrong Questions we get asked Keep going

Glaze and heat, the airway, water chambers, and the cleaning problem that decides the design.

The whole idea

A pot with a flame on it

Everything unusual about this form comes from one fact. A small area of it gets direct flame held against it, repeatedly, and then air is drawn across that area and inhaled.

Which is why the bowl is left unglazed. Vitrified stoneware handles heat well. A glaze surface under direct flame is an unknown, and there is no reason to accept an unknown here.

The rest is ordinary hollow-form building with two constraints: the airway has to survive shrinkage, and any sealed chamber has to be vented, because water left inside turns to steam in the kiln.

Start to finish

Building it

How to Make a Ceramic Pipe Bowls By Brodie
  1. Check with staff first. What is and is not fired here is the studio's call, not a matter of opinion.
  2. Use a stoneware body that vitrifies at our range. Low-fire earthenware stays porous and is the wrong material for this.
  3. Build the form solid, then hollow it, or build it hollow from the start. Either works; both need the airway planned before the walls close.
  4. Make the airway much wider than you want it. It shrinks with everything else, and a narrow channel becomes a blocked one.
  5. Vent every sealed chamber. A closed hollow form cannot dry from the inside, and any water left in it turns to steam and comes apart in the kiln.
  6. Leave the bowl unglazed, inside and around the rim. Glaze the outside if you want.
  7. Check the airway is clear at bone dry, before it fires, and again after bisque.
If it went wrong

Three things that go wrong

The airway closed up

Clay shrinks by roughly an eighth from wet to fired, and a channel that felt generous in soft clay ends up too tight to draw through. Build it far wider than the finished size.

It exploded in the kiln

Water still in the clay. A sealed hollow chamber cannot dry from the inside, and water left in it turns to steam. Every enclosed volume needs a hole, even a small one somewhere discreet.

Glaze in the bowl

Direct flame on a glazed surface is an unknown and an unnecessary one. Leave the bowl and its rim bare. Bare vitrified stoneware is the whole point of using this material.

Studio policy

Before you start

  1. Ask staff before you begin. What gets made and fired in a shared studio is the studio's decision. Ask at the start rather than at the glaze shelf, when a piece is already finished.
  2. The law is yours to know. Rules about these objects vary by state and by situation, and they are not the same everywhere. Nothing on this page is legal advice.
  3. This page is about the making. Materials, heat, airways, chambers and cleaning. It is a technical guide to a hollow form with unusual requirements.
  4. Share the room considerately. A community studio has a wide range of people in it, including families. The same courtesy applies here as to anything else somebody might not want in the middle of a shared table.
  5. Selling changes things. If work leaves the studio for money, the rules that apply to a seller are different from the rules that apply to a maker, and they are worth looking into properly first.
The part that matters most

Glaze, heat and the bowl

The single most important decision on the whole piece, and the one most people get wrong.

How to make pottery Food Safe: It's all about Vitrification Pottery to the People About vitrification rather than smokeware. Its chapters cover what vitrification is, how to test for porosity and what it means for food safety. Food safe is a separate, glaze by glaze question, which is what the Food Safe Lookup answers.
  1. Leave the bowl unglazed. Interior and rim. Direct flame on a glaze surface is not a tested condition, and there is no upside to finding out what happens.
  2. Vitrified stoneware is the material. Fired to our range it is dense, hard and non-porous, which is exactly what you want at the hot end.
  3. Never low-fire earthenware. It stays porous, holds residue and moisture, and it is a weaker body under thermal stress.
  4. No lusters or overglazes anywhere near it. Those are low-temperature surface layers with metal content, refired at low heat. Keep them off this form entirely.
  5. Nothing with lead or cadmium, which rules out most hobby paints and some imported low-fire products. Modern studio glazes are made by manufacturers who test them, and the cadmium in a bright red or orange is locked inside a stain rather than loose, but that lock has a temperature limit near the top of the stoneware range. Keep those colors off the mouthpiece, and look any glaze up in the Food Safe Lookup before it goes near your mouth.
  6. Glaze the outside freely, away from the bowl and away from the mouthpiece. That is where the decoration belongs. For the glaze firing, set the piece on a kiln cookie or glaze catcher, every time.
  7. Leave the mouthpiece bare too, or glaze it only with a glaze its maker rates for food, the way you would the inside of a mug, and look it up in the Food Safe Lookup first. It is a lip contact surface like any other.

Why unglazed is not a compromise

A properly vitrified stoneware body is already sealed. The glaze on a mug is there for the surface and for cleaning, not because the clay underneath would leak. At the bowl end you gain nothing from a coating and you accept a variable you cannot test.

The engineering

The airway

Everything about this channel is decided by shrinkage, and shrinkage is the thing beginners forget.

Clay pipe DIY Project Asahi Aki A 3D modeled pipe, a two part mold with the channel in each half, and pieces in a kiln marked 950 to 1000 C. That is a low fire mold method, so take the idea of the channel and not the clay or the firing.
  1. Build it far wider than the finished size. Clay shrinks by roughly an eighth from wet to fired. A channel that feels generous while you are making it is often too tight afterward.
  2. Keep it continuous and as straight as you can. Every bend is a place residue collects and a place a cleaning tool cannot reach.
  3. Form it, do not drill it dry. Push a skewer or a dowel through while the clay is soft, then turn it a little now and then so it never grips. Drilling bone dry chips the channel and makes dust.
  4. Work the skewer loose as it dries. Clay shrinks onto whatever is inside it, so a tool left in place can crack the piece or get stuck.
  5. Check it at bone dry and again after bisque. At bone dry, look through it toward a light and do not brush it, because dry clay dust is silica. After bisque, run a wet cleaning brush through the whole length over a bucket. Finding a blockage after glaze firing is finding it too late.
  6. Keep glaze out of it. Glaze runs into a channel, pools and narrows it, and the inside of an airway is not a surface you can reach to clean afterward.
  7. Mind the wall thickness around it. A channel cut too close to the outside leaves a thin band that cracks in the firing or in use.
Method

Building a dry piece

Three approaches, all fine, and a few things that apply whichever you choose.

Solid, then hollowed

Shape the whole form solid, let it firm to leather hard, then cut it open, hollow it and rejoin. The most forgiving route for a sculptural shape, and the joins need proper scoring.

Built hollow from the start

Pinched or slab-built around the chamber. Fewer joins and less carving, and it asks you to plan the airway before anything closes up.

Thrown parts, assembled

A small thrown bowl joined to a thrown or extruded stem. Gives clean symmetry, and the joins want matching dryness like any other assembly.

Wall thickness

A little thicker than a mug wall, and even all the way round. This form gets handled, dropped and heated, and a thin wall around a hollow chamber is the weakest thing you can build.

Rejoin at matching dryness

Both halves at the same leather hard. Score deeply, use real slip, and blend a coil along the inside of the seam where you can reach it.

Dry it slowly

A shape with a thick body and a thin stem dries at two different speeds. Cover it loosely and give it longer than it seems to need.

The harder build

Water chambers and downstems

A water vessel is a closed chamber with three openings in it, which is a genuinely harder object than a small dry piece.

  1. The chamber has to hold water. Vitrified stoneware does, provided it is fired properly and the interior is not crazed. Glaze the interior if you can reach it, and test it with water overnight before it leaves the studio.
  2. Crazing leaks. A crazed interior seeps slowly, and the fine cracks hold whatever gets into them. Choose a glaze that fits your clay body rather than one that crazes decoratively.
  3. Vent the chamber before firing. A closed chamber is the last part of the piece to dry, and any water left in it turns to steam in the kiln. It is the water, not the air, that does the damage. Here the openings are usually enough for the inside to dry and for steam to leave, but check that none of them sealed shut with glaze.
  4. Plan for a glass downstem rather than making one in clay. A slender clay tube in that position is fragile, hard to clean, and hard to size accurately through shrinkage. A socket built to take a standard glass piece is far more practical.
  5. Sizing a socket is the hard part. Shrinkage makes precise fits difficult. Build it oversized, test with the actual part after bisque, and grind the socket with a diamond pad, wet and never dry, over a bucket, in safety glasses and an N95 or better, or shim it to fit rather than hoping.
  6. Make it stable. A tall vessel full of water on a smooth base tips easily, and a fired clay piece does not survive that the way glass sometimes does. A wide foot is worth the extra clay.
  7. Weight is a feature and a problem. Stoneware is heavy. That makes it stable and it makes a drop worse, so keep the form compact rather than tall and thin.
Design for it

Cleaning, and why it decides the design

This is the thing that separates a piece somebody uses for years from a piece that gets admired once and put in a drawer. Almost every design decision above is easier to make once you have thought about cleaning.

  1. Every internal surface should be reachable. If a cleaning brush cannot get there, residue stays there permanently.
  2. Straight beats curved, every time. A dramatic curved airway looks better and cleans far worse.
  3. Wide beats narrow. A generous channel stays usable much longer before it needs attention.
  4. Unglazed stoneware is porous only if underfired. Properly vitrified, it wipes out like any other dense ceramic.
  5. Watch thermal shock. Do not put a hot piece straight into cold water. Ceramic tolerates heat well and tolerates sudden changes in it badly.
  6. Soaking is fine. Vitrified stoneware does not mind water, which is one of the real advantages of this material over some alternatives.
Read this after a bad one

What goes wrong

Blocked airway

Shrinkage, or glaze that ran into the channel. Build it much wider than the finished size and keep glaze out of it entirely.

It exploded in the bisque

Water still in the clay. A chamber with no opening cannot dry from the inside, and a piece that was not fully bone dry carries water into the kiln either way. That water turns to steam and takes the wall with it. Give every chamber an opening and let the piece dry completely.

A crack along a seam

Halves joined at different dryness, or poor scoring. Both at the same leather hard, real slip, and a coil blended inside the join.

The chamber seeps

An underfired body or a crazed interior. Fire it properly, glaze the inside where you can, and test with water overnight.

Cracked at the bowl

Usually a wall too thin at the hottest point, or a thick lump beside a thin wall, where heat stress collects. Sometimes it is thermal shock from cleaning. Build that area sturdy and even, with no abrupt thick spot.

Impossible to clean

A curved or narrow airway. Nothing to be done afterward, which is why this decision belongs at the start rather than at the end.

Questions we get asked

The ones that come up at the tables

Should the bowl be glazed?

No. Leave the interior and rim bare. Direct flame on a glaze surface is not a tested condition, and a properly vitrified stoneware body is already dense and sealed, so a coating gains you nothing there.

Can I use low-fire clay?

Not for this. Low-fire earthenware stays porous, holds residue and moisture, and is weaker under thermal stress. A stoneware body fired to vitrification is the right material.

Why did my airway close up?

Shrinkage, glaze, or both. Clay shrinks by roughly an eighth from wet to fired, so build the channel much wider than the finished size, and keep glaze out of it completely.

Why did my piece explode in the kiln?

Almost always water still in the clay, turning to steam. A sealed hollow chamber with no opening is the worst case, because its inside cannot dry and nobody can check it, and a piece that was not fully bone dry carries the same water into the kiln. It is the water, not the air. Every enclosed volume needs at least one opening.

Can I use lusters or metallic overglazes on it?

No. Those are low-temperature surface layers with metal content, and they have no place on a form that gets direct flame and airflow. Keep decoration to studio glazes on the outside, away from the bowl and mouthpiece.

Should I make the downstem out of clay?

Usually not. A slender clay tube in that position is fragile, hard to clean and hard to size through shrinkage. Building a socket to take a standard glass piece is far more practical, sized oversized and fitted after bisque.

Will a ceramic water chamber leak?

Not if the body is properly vitrified and the interior is not crazed. Glaze the inside where you can reach it, choose a glaze that fits your clay rather than one that crazes, and test with water overnight before using it.

How do I clean it?

Design for it first, with a straight, wide airway you can reach the whole length of. Vitrified stoneware does not mind soaking. Avoid putting a hot piece straight into cold water, since ceramic handles heat well and sudden changes badly.

One last thing

Design for the second year

Most of these get made for the shape and judged on the day they come out of the kiln. The ones that stay in use were designed around the boring parts: a wide straight airway, a sturdy, even wall where the heat is, a bowl left bare, and a chamber somebody can actually reach into.

None of that limits what the outside can look like. Decide the airway and the wall thickness first, then make the form whatever you want around them.

Stoneware fired to vitrification, bowl left unglazed, airway built oversized and straight, every sealed chamber vented, and a design you can clean.

If you want the full version, including water chambers and downstem sockets, switch to the Comprehensive Version at the top of the page.