Wheel and hand building
Ceramic Lamp Bases
A lamp base is a pot with two holes in it. One in the top for the hardware, one low down for the cord, and nothing between them but air. Cut those two holes while the clay is still soft and the rest of it is just a pot. Cut them after the glaze fire and you are standing over three weeks of work with a diamond bit and a spray bottle, hoping.
Jump to a section
The whole lamp, short
Make the pot around the hardware
The question that picks your build
Can you fit your whole hand inside the finished pot? If yes, you only need a short pipe at the top and a hand hole underneath. If no, you need a long threaded pipe running the full height, which means a raised foot for the cord to escape from.
Buy the lamp kit first. Not because it is the fun part, but because every measurement on this page comes off the hardware, and the hardware is eight dollars of steel that will not bend to fit your pot.
Standard lamp pipe is 1/8 IP, which is a confusing way of saying it is ⅜ of an inch across. That number decides the hole in the top. The cord decides the hole near the bottom. Everything else is a pot.
Both holes get cut at leather hard, with a hole cutter, never a knife. Both get cut oversize, because clay shrinks about twelve percent and glaze then fills in what is left. Cut the top hole at ⅝ of an inch and the cord hole at ½ an inch and you will never have to think about it again. Nobody has ever looked inside a finished lamp and been annoyed that a hole was slightly too big.
The rest of the pot wants thick walls, a wide foot and a low center of gravity, because a shade is a sail on a lever. Throw the floor narrow, about an inch across, or it will warp. Dry it slowly. Wax both hole rims before you glaze. Fire it right side up, closed, at cone 5½.
Then wire it with a UL-listed kit and follow the instructions in the box. We teach pottery. We are not electricians, and a lamp you are unsure about belongs at a lamp shop, not on a nightstand.
01 · The idea
Two holes and a road between them
Everything else is a pot
Bellied, straight, square, carved, stacked in sections, glazed in one color or nineteen. None of it changes the job. The job is a hollow route from a hole in the top to a hole near the bottom, and a form heavy enough to hold a shade up without falling over.
People put off making a lamp because it sounds like it involves electricity. It does not, or at least the clay part does not. The clay part is a vase you stopped closing at the right moment.
Here is the whole machine. A threaded steel pipe stands up through a hole in the top of your pot. A washer and a nut squeeze the pipe against the underside of that hole, which is what stops the socket wobbling. The socket screws onto the top of the pipe. The cord comes in through a small hole low in the wall, crosses the empty inside of the pot, goes up the hollow middle of the pipe, and comes out at the socket where two screws are waiting for it.
That is it. A pipe, two holes, and air in between.
Which means the difficult part of a lamp base is not skill, it is timing. Every measurement that matters has to be committed while the clay is leather hard, weeks before the piece is anything you would recognize as a lamp. There is no step later where you get to check your work against the actual hardware and adjust. The pot shrinks about twelve percent after you last touched it, the glaze thickens every edge, and then it is stone.
So the order this page is in is not decoration. Buy the kit, then measure the kit, then make a pot around those numbers. Doing it the other way round is how beautiful lamp bases end up as vases with a suspicious hole in the side.
02 · Why this page reads like this
Video teaches hands. Lists carry numbers.
What the video does better
How a hole cutter enters a wall without tearing it. How much a thick pot sags when you belly it out. What leather hard actually looks like on a form this heavy. Watch somebody do those. No sentence has ever taught them.
There is no shortage of lamp tutorials, and six good ones are linked further down this page. So it is fair to ask what a page of words is for.
A lamp base is unusual among pottery projects because most of what can ruin it is a number and a sequence, not a technique. Three eighths of an inch. Twelve percent. Cut the cord hole before the bottom goes on. Wax the rim before you dip. None of that is hard to do. All of it is easy to be missing at the exact moment you needed it.
And a number is the one thing video is worst at delivering. You watch a potter say the size of the hole, at minute fourteen, three days before you are standing at the wheel with a hole cutter in your hand. What you kept was the feeling that you knew. What you needed was the figure. You cannot scrub a video back to minute fourteen with wet clay on both hands, and you certainly cannot do it in the kiln room three weeks later when the question comes up again.
The other half of it is the sequence. A lamp base has hard gates in it. Once the piece is bisqued, cutting a hole stops being a thirty second job with a metal tube and becomes a slow, wet, careful job with a diamond bit and a real chance of cracking the pot. Watching somebody move smoothly through the right order does not teach you the order. It teaches you that an order exists.
So we wrote both. Read this once, watch a video or two, then leave the list near the bottom of this page open on your phone while you work. A page holds still. That is the entire trick, and it is why this page ends in a checklist instead of a conclusion.
03 · The hardware
Buy the kit before you touch clay
A lamp kit is a socket, a cord with a plug, a harp to hold the shade, and usually some length of threaded pipe. Hardware stores and lamp part suppliers both sell them. We do not, so this is one of the rare projects where you shop before you throw.
One question decides which kit you need
Can you get your whole hand inside the finished pot? That is the entire decision. Everything below follows from it, and it is worth answering honestly before you center any clay, because a narrow elegant pot and a wide friendly pot are two different builds.
Yes, my hand fits: the short pipe build
The cheaper, simpler, more forgiving one. Most bellied or rounded lamp bases land here.
You leave a small hole in the top, just big enough for the pipe, and a large hole in the bottom big enough to reach in through. The pipe is short, a couple of inches at most. You put the washer and nut on from underneath by feel, which is why your hand has to fit.
The cord comes in through a hole low in the side wall rather than through the bottom, so the lamp still sits flat on the table.
- Top hole: small. Just clears the pipe.
- Bottom hole: big enough for a hand, and no bigger.
- Cord hole: low in the side wall.
- Needs: nothing extra. The kit is complete.
- Watch out for: cutting the whole bottom out. A base with no floor left at all can go out of round in the glaze fire.
No, it is too narrow: the full pipe build
Tall, slim, gooseneck and stacked forms. Anything you cannot get a wrist into.
A single threaded pipe runs the whole height of the pot like a spine, and the nut goes on underneath the base instead of inside it. That means the cord and the nut both come out of the bottom, so the pot needs a raised foot or a separate pedestal with a notch, or it will rock on the nut.
If your top opening is wider than the pipe, which it usually is on a thrown form, you also need a vase cap: a small metal disc that covers the opening and gives the pipe something to seat against.
- Top hole: anything, as long as a vase cap covers it.
- Bottom hole: centered, for the pipe and the nut.
- Cord hole: in the foot, or a notch cut in the foot ring.
- Needs: pipe cut to length, plus a vase cap sized to your opening.
- Watch out for: ordering the pipe before the pot is fired. Measure the finished pot, then order.
Harp
The wire hoop the shade sits on. They come in half inch steps from six inches up to twelve, then in whole inches to fifteen. Buy it after you know how tall your base fired.
Vase cap
A shallow metal disc that hides a wide opening and seats the pipe. Sized by diameter, so measure the fired opening and not the wet one.
Felt or bumper pads
Four pads lift the base off the table and give the cord somewhere to sit. We sell these in the studio, and a lamp is the piece that needs them most.
Grab a set at the front: felt or silicone bumper pads. They are an honor system purchase, same as the rest of the shelf.
04 · The holes
Where they go, and how big
This is the part of the page to get right. Everything here happens while the clay is leather hard, and none of it can be undone cheaply afterward.
- The top holeCut it to clear the pipe, plus shrinkage, plus glaze. On a thrown form, open it out with a hole cutter before the pot leaves the bat.
- The pipeStandard lamp pipe is 1/8 IP, which measures ⅜ of an inch across the outside. Hollow, so the cord runs up the middle of it.
- Socket and harpBoth screw onto the top of the pipe. The harp holds the shade and the shade hides all of this.
- The hollow insideIt has to be genuinely open from one hole to the other. An internal shelf, a stuck coil or a partial floor will stop a cord you cannot see.
- The cord holeLow in the wall, just above where the pot meets the table. Round, sponged smooth on both sides, and never square.
- The bottomA hand hole for the short pipe build, a centered pipe hole for the full pipe build. Leave a real floor around it either way.
Cut every hole bigger than you need it
Clay gives up around twelve percent between leather hard and the end of the glaze fire, and the glaze then coats every edge and takes a little more. So both holes get cut larger than the hardware needs.
Two separate things shrink a hole after you cut it. The clay gives up around twelve percent between leather hard and the end of the glaze fire, and the glaze itself then coats every edge and takes a little more. The arithmetic is simple: divide the size you want by what is left after shrinkage. A half inch hole in a clay that shrinks twelve percent has to be cut at 0.5 divided by 0.88, which is a shade over nine sixteenths.
| Clay | Shrinks | Top hole, wet | Cord hole, wet |
|---|---|---|---|
| 52 Buff | 10% | 9/16 in | 7/16 in |
| B-Mix w/Grog | 11% | 9/16 in | 7/16 in |
| B-Mix | 12% | 5/8 in | 7/16 in |
| B-Mix w/Specks | 12.47% | 5/8 in | 7/16 in |
| Speckled Buff | 12% | 5/8 in | 7/16 in |
| Half & Half | 12% | 5/8 in | 7/16 in |
| #16 Porcelain | 13.9% | 5/8 in | 7/16 in |
| Berlin Gray | about 12% | 5/8 in | 7/16 in |
Or skip the table entirely
Cut the top hole at ⅝ of an inch and the cord hole at ½ an inch, on every clay we stock, every time. Both are a size larger than the arithmetic asks for. Both finish generously clear of the hardware even after glaze. Both are completely invisible in the finished lamp, because a socket sits on one and a table hides the other.
The only two numbers you need
Cut the top hole at ⅝ of an inch and the cord hole at ½ an inch, on every clay we stock, every time. Both are a size larger than the hardware needs. Both finish generously clear even after glaze. Both are completely invisible in the finished lamp, because a socket sits on one and a table hides the other.
Shrinkage figures are the manufacturers’ averages and clay drifts batch to batch. If you want to run your own numbers on a specific piece, the shrinkage calculator will do the arithmetic for whichever clay is on your wheel.
05 · On the wheel
Throwing a lamp base
It throws like a tall vase you never finish opening. Two things are different from a vase, and both of them are counterintuitive: the floor stays narrow, and the wall stays thick.
- Center five to eight pounds. More clay than the finished size suggests, because you are keeping the walls heavy on purpose.
- Open only about an inch across. This is the one that surprises people. A wide floor on an enclosed form warps as it dries and the lamp ends up rocking. Keep the opening small and let the belly do the widening.
- Compress the floor properly before you pull anything, then again at the end. A cracked floor on a lamp base is a cracked floor you cannot reach.
- Pull a straight cylinder first, all the height you want, then push the belly out from inside. Trying to get both at once on this much clay ends in a wobble.
- Leave the bottom third thicker than you would on a vase. That weight is the whole reason the lamp will not tip when you put a shade on it.
- Collar the top in until the opening is nearly closed. Slow the wheel down and do it in several light passes rather than one hard squeeze.
- Rib the outside smooth. Any throwing lines you leave are lines you will be sponging around a socket later.
- Let it stiffen on the bat, then trim the lower half while it is still stuck down. Wire underneath afterward.
- Cut the top hole before it leaves the bat, while it is still centered and you can see it is round.
- Flip it onto a chuck, level it, and cut the bottom hole and the cord hole. Sponge every cut edge on both sides.
Taller than one pull
A lamp base is a good excuse to learn a bigger form. If you want more height than one piece of clay gives you, the two routes are throwing it in sections and joining at leather hard, or jumping up in size a pound at a time until eight feels normal.
Related, if any of those steps were new: opening and setting the floor, compressing the floor and the rim, collaring in, using ribs and trimming.
06 · Off the wheel
Building one by hand
Hand building has one enormous advantage here, and it is worth choosing this route for that reason alone: you can cut both holes while the clay is still flat on the table. No hole cutter reaching into a dark enclosed form, no guessing where the centre is.
- Roll slabs a little thicker than usual. Around three eighths of an inch. A lamp carries weight above it for years, not a salad for an hour.
- Cut the cord hole in the wall slab now, flat on the table, before anything is assembled. Mark which end is the bottom. People do forget.
- Rib both faces of every slab to tighten the surface and cut down on warping later.
- Wait until they will hold a curve without slumping, then form the body: wrapped around a tube, pressed into slab molds, or built as a stack of coils and blended.
- Score and slip every join, then run a coil into every inside seam and blend it. You will not be able to reach some of these later, so do them as you go.
- Add the floor last, with its hole already cut, or add it whole and cut the hole while the clay is still soft enough to cut cleanly.
- Close the top over, leaving the small hole for the pipe. A flat shoulder is easier to seat a vase cap on than a curved one.
- Check the route. Poke a chopstick in the cord hole and out the top. If it snags on something, it is a coil you blended into the wrong place, and now is the only time you can fix it.
Two techniques that carry most of this
Everything above is really just score and slip done carefully, plus either blended coiling or the slab molds in the back. A lamp base is a large simple form, which makes it a genuinely good first big hand built piece.
07 · Proportion
A shade is a sail on a lever
The one minute stability test
Put the fired base on a table, empty. Push the top of it sideways with one finger, gently. If it wants to go over, it will absolutely go over once a twelve inch shade is bolted to the top of it and a cat walks past. Widen the foot on the next one.
Lamp bases fail visually far more often than they fail structurally, and it is almost always the same failure: a pot that would be a handsome vase, wearing a shade that belongs to a different lamp.
Two rules of thumb do most of the work. The shade height should be around two thirds of the base height, measured from the table to where the harp attaches. And the shade should be wider than the widest part of the base, usually noticeably wider. Sources disagree on exactly how much wider, and honestly so do we, so treat that one as a floor rather than a formula.
The third rule is not about proportion at all, it is about glare. Sit down next to where the lamp will live. At seated eye level the shade has to hide the socket, the switch and the bulb completely. If you can see the hardware, the harp is too short or the shade is, and you will notice it every single evening.
Which is the argument for making the base first and buying the shade and harp afterward. A fired pot has one height forever. A shade shop has hundreds of shades.
On weight: a stoneware base is usually heavy enough on its own, and the ones that tip are the tall narrow ones. If you want the drama of a slim lamp, get the mass into the bottom third and give it a genuinely wide foot, even if the foot is wider than the form directly above it. That small step at the bottom reads as design and behaves as ballast.
08 · Drying and firing
Thick walls, small holes, slow air
A lamp base is one of the slowest things you will ever dry. It is thick, it is mostly enclosed, and the only ventilation it has is two holes you deliberately made small.
Give it far longer than feels reasonable
Two weeks under loose plastic is not unusual for a big one, and the inside will still be damper than the outside. Slow is not a preference here, it is the difference between a lamp and a cracked lamp.
The rims dry first and crack first
Both hole edges are thin, exposed and surrounded by thick clay. They dry ahead of everything else and pull. Sponge them smooth, then keep a scrap of plastic loosely over the top hole for the first few days.
Both holes must be open before it goes in
An enclosed form with a vent is fine. An enclosed form with no vent is a pressure vessel. Look through the cord hole and out the top before you shelve it for bisque, every time, even though you know you cut them.
It is not a cheap firing
Bisque is free. Glaze firing is five cents per cubic inch with a $4.80 minimum, measured as the box the piece fits in. A six by six by nine inch base is about $16. An eight by eight by eleven is about $35. Worth knowing before you commit, not after.
Everything here is bisqued at cone 05 and glaze fired to cone 5½, which is cone 5 with a twelve minute hold at the top. If you want the longer version of what that actually does to a pot, we wrote a whole page about it. A base this size also eats real shelf space, so check your level before you plan three of them.
09 · Glazing
Glaze wants to fill your holes
Wax first, always
Wax resist on the foot, on the rim of the top hole, and around the cord hole inside and out. Two minutes with a brush before you dip, and you will never have to find out how a diamond bit feels on a piece you love.
Dipping a lamp base is the moment the project is most likely to quietly ruin itself, and the reason is boring. A hole that measured a comfortable half inch at bisque gets coated on every surface, and glaze does not spread evenly across an opening. It pools. It bridges. It fires into a solid plug that looks, from the outside, exactly like a hole.
So wax both hole rims before you dip. If you would rather not wax, then run a wooden dowel or a brush handle through both holes immediately after dipping, while the glaze is still wet enough to move, and check them again once the piece is dry to the touch. Waxing is easier.
Two more things that are specific to this shape. Do not glaze the inside. Nobody will ever see it, it adds weight, and any glaze that runs down in there will pool at the bottom and possibly find the cord hole. And fire it right side up, on its own foot, which means the foot has to be clean and the glaze has to stop well short of it.
Beyond that a lamp base is a large uninterrupted surface, which makes it one of the best pieces in the studio to put a real glaze on. Something that breaks over an edge, something that moves. The glaze finder will tell you where any of the 650 or so are on the wall, and the dipping glaze page covers the technique for a piece this big.
10 · Troubleshooting
Six ways a lamp base goes wrong
Three ways a lamp base goes wrong
All six are avoidable, and five of them are avoidable at a stage where fixing them costs nothing at all.
These are the three that actually happen on a first lamp, and all three are avoidable before the piece is dry.
- The hole closed up in the glaze fireThe fix is a diamond bit, run wet and slow, with a mask on and the piece resting on foam. It usually works. It is also completely avoidable with two minutes of wax resist, which is why waxing is on this page twice.
- It cracked out from the cord holeA knife leaves corners, and a corner is where a crack starts. Cut round holes with a hole cutter, sponge both sides of the edge, and never put a hole in a wall that is already past leather hard.
- It rocks on the tableUsually the floor was opened too wide, or too much of the bottom was cut away. Sand it flat on a diamond pad, then let a set of bumper pads take care of the last of it. That is what they are for.
- The socket sits crookedThe top hole was not centered, or the pot leaned while it dried. Cut the top hole while the piece is still on the wheel and centered, and dry it on a flat board rather than a shelf with a warp in it.
- It came apart in the bisqueEither it went in damp, or one of the holes was blocked and it had nowhere to vent. Thick enclosed forms are the least forgiving things in the kiln. Give it another week and check the holes again.
- The cord will not go throughSomething inside is in the way, usually a coil pushed in during blending or a floor that was added at an angle. Test the route with a chopstick while the clay is still soft. It takes four seconds and saves the whole piece.
If a piece did come out of the kiln with a problem you can still work with, the fixing fused and sharp pottery page covers the grinding tools we keep in the studio and how to use them without making it worse.
11 · Assembly
Wiring it, in order
Read this part first
Buy a UL-listed lamp kit and follow the instructions that come in the box, because those instructions are for the exact parts in your hands and this page is not. What follows is the order things go in, so the steps make sense when you get there. If any of it leaves you unsure, take the base to a lamp shop and have them wire it. They charge very little, and a lamp you are not confident about does not belong on a nightstand.
- Thread a nut onto the pipe, then a lock washer, then a check ring. That stack is what will squeeze against the inside of your top hole.
- Push the pipe up through the top hole from inside the pot, with that stack on the inside. On a full pipe build it goes the other way, up from the bottom, and the nut lands under the foot.
- On the outside, add another check ring, a neck if you want the socket raised, the saddle of the harp, and a lock washer.
- Screw the socket base on and tighten the whole stack until nothing rotates. Sight down the lamp and make sure the harp is square to the front.
- Feed the cord in through the cord hole, across the inside, and up the middle of the pipe until a couple of inches come out the top.
- Separate and strip the two wires, about half an inch each.
- Tie an underwriter’s knot in the cord just below the socket. Your kit will have a diagram. It stops a tug on the cord pulling on the screw terminals, and it is not optional.
- Run a fingernail along each wire. One is ribbed and one is smooth. Ribbed is neutral and goes clockwise around the silver screw. Smooth is hot and goes clockwise around the brass screw.
- Slide the cardboard sleeve and the shell over the socket and snap it down. Check no bare wire is touching anything but its own screw.
- Pull the slack back out of the bottom, stick four bumper pads on the foot so the cord has somewhere to sit, then add the harp, the shade, the finial and a bulb.
12 · The videos
Four more lamps, four more potters
Two lamps, two potters
Two of the six are already up the page, sitting next to the method they belong to. These four are complete builds worth watching end to end, and none of them are us.
Two complete builds, start to finish. Between them they cover a small lamp, a large one, and the wiring at the end. Neither of them is us.
Keep this open at the wheel
The whole lamp, on one screen
Tap copy and it lands in your notes app, so you are not scrolling a page with slip on your thumb.
Before you make anything
- Buy the lamp kit first
- Lamp pipe is 3/8 inch across
- Hand fits inside? Short pipe build
- Hand does not fit? Full pipe, raised foot
- Wide opening? You also need a vase cap
- Buy the harp and shade after it fires
While the clay is soft
- Open the floor one inch, no wider
- Keep the bottom third thick
- Top hole at 5/8 inch, hole cutter
- Cord hole at 1/2 inch, low in the wall
- Round holes only. Never a knife
- Sponge every cut edge, both sides
- Chopstick test: cord hole to top, no snag
- Leave a real floor around the bottom hole
Drying, glazing, firing
- Dry it slowly. Two weeks is normal
- Cover the top hole rim for a few days
- Both holes open before bisque
- Wax both hole rims before you dip
- No glaze inside. Clean foot
- Fire right side up at cone 5½
- Bumper pads on the foot at the end
Questions we get asked
The ones that come up at the wheel
If yours is not here, ask any of us in the studio. Lamps are a project we enjoy talking about, mostly because so few people try one.
Do you sell lamp kits at the studio?
No. We sell clay, glaze, firings and a small shelf of tools, and lamp hardware is not on it. Hardware stores carry basic kits and online lamp part suppliers carry everything else, including pipe cut to length and vase caps by diameter. We do sell bumper pads, which a lamp genuinely needs.
Can I turn a pot I already fired into a lamp?
Often, yes. You need a diamond hole saw made for tile and glass, water to keep it cool and hold the dust down, a mask, eye protection and a lot of patience. Go slow, use almost no pressure, keep it wet, and rest the piece on foam. It works far more often than people expect. It also fails sometimes, so do not learn on the piece you love.
Which clay should I use?
Any of the eight we stock will make a lamp. If you want the easiest ride, B-Mix w/Grog is the obvious pick: the grog makes a thick heavy form dry and fire more forgivingly, and it shrinks less than most, which means slightly less hole arithmetic. #16 Porcelain is the hardest, because it shrinks nearly fourteen percent and is less tolerant of thick walls.
What will it cost to fire?
Bisque is free. Glaze firing is $0.05 per cubic inch of the box the piece fits inside, with a $4.80 minimum. A six by six by nine inch base comes to about $16. An eight by eight by eleven comes to about $35. There is a cap of $600 for anything over 12,000 cubic inches, which no lamp base will ever get near.
Can I wire it here?
You are welcome to put your hardware together at a table, and people do. But we are a pottery studio, we do not teach wiring, and we are not the right people to check your work. Follow the instructions that came with your kit, or take the fired base to a lamp shop and let them do it.
Does the inside need to be glazed?
No. Nothing goes in there but air and a cord, nobody will see it, and glaze inside an enclosed form tends to pool where you cannot reach it. Leave it bare stoneware.
How big can I make one?
Bigger than you think, but bring the idea to one of us before you start rather than after. Two things set the ceiling: what fits in the kiln, and how much shelf space your level gives you while it dries. Both are easier to talk through in person with the actual dimensions.
One last thing
Make the pot around the numbers
Almost nobody makes a lamp, and the reason is that it sounds like two hobbies stacked on top of each other. It is not. It is one pot with two holes in it and a kit from a hardware store, and the only genuinely unforgiving part is that the measurements have to be right weeks before you can check them. Buy the kit, write the two numbers on the back of your hand, and the rest is throwing.
That is the short version, and it is enough to go and make one. If you want the arithmetic behind the hole sizes, the two hardware routes explained properly, four more videos and the things that go wrong, switch back to the Comprehensive Version at the top of the page.
The videos on this page belong to the potters who made them and are linked, not reposted. Hole sizes assume standard 1/8 IP lamp pipe; if your kit uses something else, measure it and redo the division. Nothing here is electrical advice.
Hole sizes assume standard 1/8 IP lamp pipe. If your kit uses something else, measure it. Nothing here is electrical advice.
Which version would you like to print?
Videos come out as a labelled box with the title and channel to search for, since paper does not play them.