Using Cookie Cutters on Clay Slabs
Cookie cutters look like the easiest thing in pottery and produce more disappointing results than almost anything else. Torn edges, stuck shapes, a sharp lip that has to be sanded off later. There is one trick that fixes nearly all of it, and it costs about a dollar.
Lay plastic wrap over the slab, then cut through it. The cutter presses the wrap into the edge, which rounds it and stops the clay sticking. Cut a firm slab, lift the cutter straight up, and let the shapes dry flat between boards.
A cutter makes a wound, not an edge
A metal cutter pushed into clay does two unhelpful things. It drags clay down the inside of the blade, which tears the edge, and it leaves a sharp square lip that catches on everything afterward.
Plastic wrap fixes both at once. Laid over the slab and cut through, it stops the blade touching the clay directly, so nothing sticks, and it gets pressed down into the cut, which rolls the edge over into a soft round.
One sheet of kitchen wrap, and the finishing work at the other end disappears.
The route that works
- Roll a slab and let it firm up. Soft slab tears and distorts. You want it holding its shape but still flexible.
- Lay plastic wrap flat over it, smoothed out. Wrinkles print into the clay.
- Press the cutter straight down through the wrap, in one go.
- Lift the cutter straight up. No twisting. Twisting is what smears an edge you just made clean.
- Peel the wrap back and the shape is sitting there with a rounded edge.
- Lift the shape with a thin blade, not your fingers, so it stays flat.
- Dry it between two boards with a sheet of paper each side, or it curls as it dries.
Three things that go wrong
They curled as they dried
Flat shapes warp, always, because the top dries faster than the bottom. Drying them between two boards under a little weight is not optional, it is the technique.
The slab was too soft
The cutter pushed the clay rather than cutting it, so the shape came out stretched and the edges tore. Let the slab firm up before you cut.
You twisted the cutter
Every twist drags the edge sideways and undoes the rounding the wrap just gave you. Straight down, straight up.
The plastic wrap trick
If you read nothing else here, read this. It is the difference between shapes that need ten minutes of cleanup each and shapes that need none.
- Lay the wrap over the slab, not under it. A single smooth sheet, no wrinkles, pressed lightly so it sits flat against the clay.
- Cut straight through it. The cutter goes through wrap and clay together in one press.
- The wrap stops the clay sticking. Nothing touches the blade directly, so no clay drags up the inside and no shape has to be poked out.
- And it rounds the edge. The wrap gets carried down into the cut and folds over the corner, leaving a soft rolled edge instead of a square lip.
- Which removes the finishing work entirely. No sponging the edge, no sanding at bone dry, no sharp corner that chips in the kiln.
- One sheet does many cuts. Leave it in place and keep cutting through the same piece until it tears.
Why a rounded edge matters beyond looks
A square edge is the thinnest part of the piece and the first thing to chip, in handling and in the kiln. It also holds glaze badly, because glaze pulls back off a sharp corner and leaves it bare. Rounding it is a durability fix as much as a finish one.
Getting the slab right first
Most cookie cutter failures are slab failures wearing a disguise.
- Even thickness matters more than the number. Around a quarter inch suits most shapes. What actually causes problems is one end being thicker than the other, which warps as it dries.
- Let it firm up before cutting. Soft slab stretches under a cutter instead of parting, so the shape comes out slightly larger and slightly distorted, with torn edges.
- Not leather hard, though. Too stiff and the cutter cracks the clay instead of slicing it. You want it holding its shape but still giving.
- Compress both sides. A rib over the slab before cutting closes the surface and makes cracking far less likely later.
- Roll on canvas, then flip. Canvas texture on both sides is even; texture on one side only is a warp waiting to happen.
- Cut from the middle outward, and keep cuts close together. Every cut relaxes the slab a little, so shapes cut last from a stretched edge come out least accurate.
Which cutters are worth using
A kitchen drawer full of them is a perfectly good starting point, with a few exceptions.
Metal cutters
The best cut, because the blade is thin. They also rust if put away wet, and thin tin ones bend out of shape quickly. Dry them like any other studio tool.
Plastic cutters
Never rust, never bend, and the thicker edge gives a slightly less crisp cut. Perfectly good, and they are what most people already own.
Cutters with a plunger
Sold for fondant, and the plunger that ejects the shape also stamps a pattern into it. Useful, and the wrap trick makes the ejector largely unnecessary.
Deep cutters beat shallow ones
A tall cutter stays square as you press. A shallow one flexes, and a flexed cutter gives a shape with a wandering edge.
Avoid very intricate shapes
Fine points and thin connecting bits are weak in clay in a way they are not in dough. They break at the greenware stage, and again in the kiln.
You can make your own
A strip of thin metal or stiff plastic bent to a shape and taped closed cuts perfectly well. Worth knowing before you buy a set for one project.
Cutting, lifting and drying
Cutting is thirty seconds. Drying flat is where the shapes are actually won or lost.
- Press straight down, one movement. Rocking the cutter gives an edge that is rounded on one side and torn on the other.
- Lift straight up, no twist. The twist feels helpful and it smears the edge every time.
- Peel the wrap back slowly so it does not lift the shape with it.
- Lift the shape with a thin metal blade, sliding underneath. Fingers stretch a soft shape out of true.
- Lay them on paper, not bare board. Clay sticks to board as it dries and tears when you lift it.
- Sandwich them. Paper, shapes, paper, then a second board on top. A little weight if they are thin.
- Dry slowly. Two or three days, checking that they are drying evenly rather than from one edge.
- Turn them over once partway through, so both sides see air.
Why flat things warp
A flat shape has no structure holding it. The top surface is exposed to air and the underside is not, so the top dries and shrinks first and the whole thing curls upward at the edges. Boards and paper slow the top down until both sides match.
Beyond flat shapes
Cutters are a shape-making tool, not just an ornament tool, and that is where they get interesting.
Drape them over a mold
Cut a shape, then lay it over a slab mold or a curved former. The outline stays crisp and the piece gains a curve, which turns a flat star into a small dish.
Cut holes rather than shapes
The negative is often better than the positive. A cutter used on the wall of a piece leaves a pierced shape, which reads beautifully with light behind it.
Press, do not cut
Push the cutter partway in and lift it away, leaving an outline rather than a cut. That gives a raised or recessed motif you can then carve or fill with wash.
Build with the shapes
Cut walls for a small box, matched sides for a lidded form, or repeated tiles. Cutters give you identical pieces, which is exactly what construction needs.
Stack them
Two or three of the same shape, joined with slip in a slight offset, gives depth and a shadow line no single slab has.
Hanging pieces
Punch the hole while the clay is soft and make it larger than you think, because the hole shrinks with everything else and glaze narrows it further.
What goes wrong
Everything curled
Dried in open air. Flat shapes need to be sandwiched between boards with paper on both sides. This is the single most common failure and it is entirely preventable.
Torn, ragged edges
Slab too soft, or cutting without the wrap. Firm the slab, lay the wrap, and press rather than saw.
The shape stuck in the cutter
No wrap. That is the problem the wrap exists to solve, and poking the shape out from the back distorts it every time.
Cracks at thin points
An intricate shape with a narrow neck. Clay is not dough, and fine connecting sections fail at greenware or in the firing. Choose simpler outlines.
Shapes came out different sizes
Cut from a slab that stretched as you worked across it. Cut from the middle outward and keep the cuts close together.
The hanging hole closed up
Shrinkage plus glaze. Punch it noticeably bigger than the final hole you want, and clean glaze out of it before firing.
The ones that come up at the tables
Why does plastic wrap help?
Two reasons. The blade never touches the clay, so nothing sticks inside the cutter. And the wrap is carried down into the cut and folds over the corner, leaving a soft rounded edge instead of a sharp square lip.
Why did my shapes curl up as they dried?
Because the top dried faster than the bottom and shrank first. Flat shapes have no structure to resist it. Dry them between two boards with paper on each side, turning them over once partway through.
How firm should the slab be?
Firm enough to hold its shape, soft enough to still give. Too soft and the cutter stretches the clay instead of parting it. Too stiff and it cracks rather than cuts.
Can I use cutters from my kitchen?
Yes, and most people do. Metal gives the crispest cut and needs drying so it does not rust. Deep cutters work better than shallow ones because they stay square under pressure.
Why did the thin parts of my shape crack?
Clay is not dough. Fine points and narrow connecting sections are structurally weak, and they fail at greenware or in the kiln. Pick simpler outlines, or thicken the slab for intricate ones.
How big should a hanging hole be?
Bigger than you want it to end up. The hole shrinks along with the rest of the piece, and glaze narrows it further. Clean the glaze out of it before it goes in the kiln.
Should I smooth the edges afterward?
With the wrap, mostly not, which is the point of it. If you do need to tidy an edge, do it at leather hard with a damp sponge rather than sanding at bone dry, which makes dust.
Can I do anything more interesting than flat ornaments?
Plenty. Drape a cut shape over a slab mold for a dish, cut holes in the wall of a piece for a pierced pattern, press without cutting for a raised motif, or use cutters to make identical panels for a box.
Where to go next
Slab molds and how to use them
Where a cut shape becomes a dish, and the tool that gives a flat piece a curve.
Read it →Makers marks
Stamping a mark into a flat shape, and why leather hard is the moment for it.
Read it →Making and using pottery washes
The finish that suits a pressed motif, wiped back so it sits in the lines.
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 →The easiest technique with the most failures
Cookie cutters get handed to beginners because they look foolproof, and then the shapes come out torn, stuck and curled, and people decide hand building is not for them. None of that was about skill.
Firm the slab, lay a sheet of wrap over it, press straight down and lift straight up, then dry the shapes between two boards. Four changes, none of them difficult, and the results stop looking like a first attempt.
Wrap over the slab, cut through it, no twisting, lift with a blade, dry between boards with paper. The wrap stops sticking and rounds the edge in the same move.
If you want the slab detail and what to do beyond flat shapes, switch to the Comprehensive Version at the top of the page.
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