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.
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 or it explodes.
Building it
- Check with staff first. What is and is not fired here is the studio's call, not a matter of opinion.
- Use a stoneware body that vitrifies at our range. Low-fire earthenware stays porous and is the wrong material for this.
- 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.
- Make the airway much wider than you want it. It shrinks with everything else, and a narrow channel becomes a blocked one.
- Vent every sealed chamber. A closed hollow form with no escape for steam and air comes apart in the kiln.
- Leave the bowl unglazed, inside and around the rim. Glaze the outside if you want.
- Check the airway is clear at bone dry, before it fires, and again after bisque.
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
A sealed hollow chamber with no vent. Trapped air and steam expand with nowhere to go. 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.
Before you start
- 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.
- 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.
- This page is about the making. Materials, heat, airways, chambers and cleaning. It is a technical guide to a hollow form with unusual requirements.
- 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.
- 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.
Glaze, heat and the bowl
The single most important decision on the whole piece, and the one most people get wrong.
- 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.
- 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.
- Never low-fire earthenware. It stays porous, holds residue and moisture, and it is a weaker body under thermal stress.
- 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.
- Nothing with lead or cadmium, which rules out most hobby paints and some imported low-fire products. Studio glazes fired to stoneware temperature do not have this problem.
- Glaze the outside freely, away from the bowl and away from the mouthpiece. That is where the decoration belongs.
- Leave the mouthpiece bare too, or glaze it with the same studio glaze you would put on the inside of a mug. 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 airway
Everything about this channel is decided by shrinkage, and shrinkage is the thing beginners forget.
- 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.
- Keep it continuous and as straight as you can. Every bend is a place residue collects and a place a cleaning tool cannot reach.
- Form it, do not drill it dry. Push a skewer or a dowel through while the clay is soft, twisting it out cleanly. Drilling bone dry chips the channel and makes dust.
- 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.
- Check it at bone dry and again after bisque. A cleaning brush through the whole length. Finding a blockage after glaze firing is finding it too late.
- 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.
- 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.
Building a dry piece
Two approaches, both fine, and a few things that apply either way.
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
Thicker than a mug wall. 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.
Water chambers and downstems
A water vessel is a sealed form with three openings in it, which is a genuinely harder object than a small dry piece.
- 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.
- 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.
- Vent the chamber before firing. A sealed vessel needs a route for steam and expanding air. Here the openings are usually enough, but check that none of them sealed shut with glaze.
- 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.
- Sizing a socket is the hard part. Shrinkage makes precise fits difficult. Build it oversized, test with the actual part after bisque, and grind or shim to fit rather than hoping.
- 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.
- 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.
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.
- Every internal surface should be reachable. If a cleaning brush cannot get there, residue stays there permanently.
- Straight beats curved, every time. A dramatic curved airway looks better and cleans far worse.
- Wide beats narrow. A generous channel stays usable much longer before it needs attention.
- Unglazed stoneware is porous only if underfired. Properly vitrified, it wipes out like any other dense ceramic.
- Watch thermal shock. Do not put a hot piece straight into cold water. Ceramic tolerates heat well and tolerates sudden changes in it badly.
- Soaking is fine. Vitrified stoneware does not mind water, which is one of the real advantages of this material over some alternatives.
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
A sealed chamber with no vent, or the piece was not bone dry. Both put pressure inside a closed volume with nowhere to go.
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, sometimes thermal shock from cleaning. Build that area thicker than feels necessary.
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.
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 a sealed hollow chamber with no vent, or a piece that was not fully bone dry. Trapped air and steam expand with nowhere to go. 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.
Where to go next
What pottery glaze actually is
Vitrification, crazing and why a glaze either fits a clay body or does not.
Read it →Hanging wall vases
Another sealed form that has to hold water, and how to test one before it matters.
Read it →Pottery in humid vs arid climates
Drying a shape with a thick body and a thin stem without cracking it.
Read it →Clay Hole University
Every lesson and guide in one place, from first day at the wheel through firing and glaze chemistry.
Start there →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 thick 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.
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