Glazing · Making a glaze catcher
Insurance for a glaze you know is going to run.
A shallow unglazed dish the pot stands on in the kiln, so a runny glaze drips into it and not onto the shelf. Thrown catchers, pinch pot catchers, and the glue and clay ball trick on a cookie: three versions of one rule, which is same clay, wider than the foot, and something between them that will not fuse.
Four steps with a tick list at each: deciding and preventing, the thrown stack, the pinched saucer, and the ball trick. Six fixes and five videos, three from potters who fire runny glazes on purpose.
This is the short version: the decision, the three versions and the rule, each with a tick list. The prevention detail, the alumina note and the questions are in the comprehensive version.
Read it, then watch it
Why this is written down and filmed, both.
A glaze catcher is a small object with three versions and one rule, and the rule, same clay, wider than the foot, something between them that does not fuse, is a sentence you carry to the kiln. The three versions are thrown, pinched, and three balls of clay glued to a cookie, and each is a two-minute make you have to see once. The rule and the tick lists are here. The videos are the two minutes.
Use both, in this order
Read the rule. Watch the version you will make. Make a stack of them on a slow night, before the pot that needs one exists.
The whole idea
Same clay, wider than the foot, something between them that will not fuse.
A shallow unglazed dish the pot stands on in the kiln, so a runny glaze drips into it and not onto the shelf. Throw them off the hump, pinch them, or glue three pea-sized balls of clay to a cookie so the foot stands clear. Same clay as the pot, an inch wider than the foot, a waxed band above the foot. Every flux glaze runs.
The five-minute version
The whole technique in six moves.
If you already glaze and you just want the shape of it, this is the shape of it. Everything below is these six moves, slowed down and with the places they fail marked.
Before a runny glaze
What you need on the table.
Six things, and one of them is a slow night. Catchers are made in stacks before they are needed.
Clay from the pot’s bag, a cookie, white glue, alumina or kiln wash, wax resist, and a slow night to make a stack.
Step one
Decide whether the glaze can run, and prevent what you can.
A catcher is insurance, and prevention comes first. Any glaze that can move wants both: a flux glaze, a thick overlap, three coats on a wall, a glaze marked as a runner, a glaze you have never fired. Our flux glazes run by design; every pot under them gets a catcher.
Prevention is cheap. Glaze thinner in the bottom third of any pot with a runner on it. Wax the foot and a band a quarter inch above it, so the glaze stops at the band with room to move before it reaches the foot. Two coats rather than three on anything that flows. Trim a small groove at the foot as a drip line, per Chic Lotz’s video below, so a drip that reaches it stops there. Our resists lesson is the waxing.
Then the catcher, for the day all of that is not enough. Three kinds, all of them the same clay as the pot, all of them wider than the foot by an inch, all bisqued before they go under anything. Make them in a stack on a slow night; the pot that needs one is never the pot you have time to make one for.
How far a drip travels
A drip that reaches the foot of a mug has usually travelled an inch or so down the wall and spreads about half an inch across a flat surface before the kiln cools. That is why a catcher is an inch wider than the foot all round rather than a hair, and why a waxed band a quarter inch above the foot catches most drips before they become one. Thicker glaze travels further; a flux glaze over a runner travels furthest of all.
Step two
Thrown catchers: a stack of shallow plates off the hump.
A saucer with a small rim. Off the hump, a few ounces each, opened flat with a slight rise at the edge, a quarter inch thick, an inch wider than the foot of the pots you make most. Wire off, dry between boards, bisque. A dozen in twenty minutes.
A raised centre helps: a low bump in the middle the foot sits on, so a drip runs off the foot and down into the moat rather than pooling under it. Throw it as a shallow dome inside the saucer, or press one on afterwards. Old Forge Creations throws exactly this, a batch at a time, in the second video.
The face gets a release before use: alumina hydrate mixed with a little water and brushed on, or a coat of kiln wash. A drip on an alumina-washed catcher chips off with a fingernail; a drip on bare bisque is a fuse. Alumina is bring-your-own here, and a small tub of it is one of the better things a potter can own. Our off-the-hump lesson is the method for the stack.
Step three
Pinched catchers: a flattened pinch pot with a bump.
No wheel needed. A pinch pot pressed flat on a board into a saucer, a quarter inch thick, a small ball of clay blended onto the centre as a bump for the foot. Rim turned up a little. Dried between boards, bisqued, washed with alumina.
Or from a slab: a circle cut an inch wider than the foot, compressed both faces with a rib, edges turned up over a finger, a bump pressed on. Slab catchers warp more than pinched or thrown ones, so the compression and the slow drying matter more. Either way the rules are the same as for any plate, and our flat tiles lesson is the drying method.
A pinched catcher is the right one for an odd-shaped foot, a sculpture, or a pot that is not round, because it can be pressed to fit. Make it on the pot’s base while both are leather hard, with a sheet of plastic between, and it will match.
Step four
The ball trick: three peas of clay glued to a cookie.
The foot never touches anything. Three pea-sized balls of the pot’s clay, glued to a cookie with white glue in a triangle under the foot, and the pot stood on them. A drip runs off the foot onto the cookie below, and the foot cannot fuse to anything. After firing the balls snap off and the marks grind away.
Pea-sized is the whole trick. Big balls fuse to the foot; tiny ones snap. The foot has to be bare and waxed, because a glazed foot fuses to anything. The glue holds the balls in place on the drop-off table and burns out in the kiln with no trace. Dallas Wooten shows the whole thing in two minutes in the third video.
Here, every piece already goes into the kiln on a cookie with a naked bottom, so the ball trick is our normal cookie with three peas on it, and the pot and the cookie go on the drop-off table together. It makes the box a hair taller, a few cents at five cents a cubic inch. A drip ground off a shelf is a good deal more than a few cents, and our staff, who load every kiln, notice who uses catchers.
Watch it done
Now watch five people catch drips.
Watch this one, then go throw a stack.
None of these potters work here or know we exist. Between them they cover how and why, throwing a batch, the clay ball trick, catchers for shelves, and stopping the drip at the pot. Nothing but the still frame loads until you press play.
Ten minutes from a potter who fires runny glazes on purpose, on what a catcher is for and how he throws them. The other four videos are in the comprehensive version.
When it goes wrong
Six ways it goes wrong, and what to do about each.
The three failures that happen on the first runny glaze.
Pick the one that looks like your kiln load. The first three are the catcher. The last three are the balls, the warp, and the happy one.
The pot fused to the catcher
The glaze ran down the foot and onto the catcher, and the catcher was bare clay, so the two fired into one. A catcher without a release is a very expensive shelf.
Alumina hydrate or kiln wash on the catcher’s face, or a dusting of alumina on the foot, or the clay ball trick so the foot never touches anything. Wax the foot and a line a quarter inch above it.
Tap it. Sometimes a light tap with a wooden mallet at the join snaps a small fuse cleanly. Then a diamond pad, wet, on the foot. Our fused pottery lesson is the method, and our staff will have seen worse.
The catcher cracked in the kiln
Thin, or dried too fast, or a different clay from the pot so it shrank at a different rate under a hot pot. A catcher is a plate, and plates crack.
The same clay as the pot, a quarter inch thick, compressed with a rib, dried slowly between boards. Bisque it before it is used.
A cracked catcher that held the drip did its job. Bin it and throw three more.
The glaze ran past the catcher onto the shelf
The catcher was too small for the pot, or the pot was set off centre on it, or the glaze was thick enough at the foot to run further than a catcher could hold.
A catcher an inch wider than the foot all round. Pot centred on it. Glaze thinner in the bottom third of any pot with a runner on it, and a bare band above the foot.
Tell the studio team. A drip on a shelf is ground off with a diamond pad and the shelf rewashed, and it is far better said than found.
The clay balls stuck to the foot
The balls were too big, or the foot was glazed, or the balls were the wrong clay. Three tiny balls under a bare foot fall away with a tap; three big ones under a glazed foot become part of the pot.
Pea-sized, the same clay as the pot, under a waxed and bare foot, glued to the cookie so they cannot roll. They snap off after firing and the marks grind away in seconds.
Snap them off with pliers, then a diamond pad on the three marks. A minute each.
The catcher warped and the pot sat crooked
A thin catcher dried on one face, or fired with a heavy pot off centre on it, or made from a slab that was never compressed.
Compress both faces with a rib. Dry between boards. Throw catchers rather than cutting them from slab if you have a wheel; a thrown plate is compressed by nature.
A warped catcher is a warped catcher. Make the next one thicker and slower.
You made ten catchers and never needed one
The glaze did not run, because it was applied thin, stopped at a bare band, and fired at cone 5½ where it is stable. That is the goal.
Keep making them. A catcher is insurance, and insurance you did not need is the good outcome. Use them under anything with a flux glaze, a thick overlap, or a glaze the wall marks as a runner.
Stack them on your shelf. The day you try Running Hot Chowder over something, they are the most useful thing you own.
How it works here
At The Clay Hole, a catcher is a cookie that grew up.
This page is written for potters everywhere. A few things are specific to our building, so you know before you start.
Three things to know here
Every piece already goes into our kilns on a cookie with a naked bottom; a catcher is that cookie with a rim, a bump or three balls, and the two go to the drop-off table as one thing. Alumina and kiln wash are bring-your-own. Our four flux glazes run by design, and every pot under them wants a catcher.
Cookies and catchers
Every glazed piece goes in on a cookie with a bare bottom, no exceptions. A catcher is a cookie with a rim, a bump or the three balls, made from the pot’s clay, and it goes to the drop-off table under the pot as one thing. Our staff load every kiln, and a catcher tells them the glaze might move.
The flux glazes
Honey Flux, Light Flux, Dark Flux and Running Hot Chowder are runners by design. Thinner in the bottom third, a waxed band above the foot, two coats, and a catcher under every one.
Alumina and kiln wash
Bring-your-own; we do not stock them. A small tub of alumina hydrate lasts years and makes a drip chip off a catcher with a fingernail. Tell the studio team before anything you have brought in goes into a kiln, which is the rule for every outside material.
Firing
Bisque is cone 05 and free, and catchers are bisqued with your other work. The glaze firing is cone 5½ at five cents a cubic inch, $4.80 minimum, on the longest dimension, so a catcher adds a few cents to the box. If a glaze reaches a shelf anyway, tell the studio team; it is far better said than found.
Questions people actually ask
The ones that come up every week.
What is a glaze catcher?
A shallow unglazed dish of the same clay as the pot, wider than the foot, that the pot stands on in the kiln so a runny glaze drips into it instead of onto the shelf. A cookie is a flat one; a catcher has a rim, or a raised centre, or the clay-ball trick that lifts the foot clear. Insurance for a glaze you know is going to run.
When do I need one?
Any time a glaze might move: a flux glaze, a thick overlap of two glazes, a glaze the wall marks as a runner, three coats on a vertical surface, or a glaze you have never fired before. Our flux glazes, Honey, Light, Dark and Running Hot Chowder, are runners by design and every pot under them wants a catcher.
What clay?
The same clay as the pot. A catcher in a different body shrinks at a different rate under a hot pot and cracks, and a groggy catcher under a smooth pot can leave marks. Throw or cut them from the same bag.
Do I glaze the catcher?
No. Bare bisque, or bare bisque with a release on the face: alumina hydrate mixed with a little water and brushed on, or kiln wash. Alumina is bring-your-own here and worth owning; a glaze drip on an alumina-washed catcher chips off with a fingernail.
What is the clay ball trick?
Three pea-sized balls of the pot’s clay, glued to a cookie with white glue in a triangle under where the foot will sit. The pot stands on the balls, clear of the cookie, so a drip runs off the foot and lands on the cookie without the foot ever touching anything it can fuse to. After firing the balls snap off and the three tiny marks grind away. The glue burns out.
Can I stop the drip instead?
Mostly, yes. Glaze thinner in the bottom third. Wax a band a quarter inch above the foot so the glaze stops there. Trim a small groove at the foot as a drip line, per Chic Lotz’s video. Use two coats instead of three on anything that runs. The catcher is for when all of that is not enough, which with a flux glaze is often.
How does this work at The Clay Hole?
Every piece already goes into our kilns on a cookie with a naked bottom, so a catcher is a cookie with a rim or with the balls glued on, and it goes on the drop-off table under the pot as one thing. It makes the box a little taller, which is a few cents at five cents a cubic inch; a drip ground off a shelf is a good deal more than that. Our staff load the kilns and will thank you.
Related lessons
Six lessons that sit next to this one.
Three to read next.
A catcher sits between a runny glaze and a kiln shelf. These are the pages on either side.
That is the whole technique
Same clay. Wider than the foot. Something between them. Made before you need it.
Your first catcher will be too small for the pot you put on it, and the second stack will be an inch wider all round. After that they sit on your shelf costing nothing until the night you try Running Hot Chowder over a celadon, and then they are the most useful thing you own.
If you want the prevention detail, the alumina note and the answers to the questions everybody asks, switch to the comprehensive version at the top. Otherwise, go throw a stack of saucers.
Written for potters everywhere. Where our studio does things differently, the page says so.
Which version would you like to print?
Both print clean, with the videos turned into labelled boxes you can search for later.