Arts 101: Ceramics Lingo

Scraffito and blunging may suggest the inventive vocabulary created by Harry Potter author J.K. Rowling, but they’re actually terms you might overhear in a conversation among real-life potters.

Today we continue our series explaining unusual words and phrases in the arts by looking at the language of the ceramic arts, sometimes referred to as pottery.

According to ceramic artist Kip O’Krongly, the question of whether it’s called “ceramics” or “pottery” arises because ceramics is a functional art form, putting it in a category that straddles art and craft.

A display with examples of work by Kip O'Krongly

A display of some of ceramic artist Kip O’Krongly’s work

In expressing herself through her work, O’Krongly embraces both the functional and artistic aspects of ceramics. Acknowledging that people use ceramics on a daily basis, often at mealtimes, O’Krongly infuses her work with images of topics that interest her; specifically, food production, transportation and energy. “There is this really intimate relationship with pots that maybe we don’t have with other art forms,” she asserts. “The dinner table is a great place for conversation, so I’m hoping that with people using these bowls, cups and dishes, it’s a way to start conversations and to ask questions about these social issues.”

The Northern Clay Center

The Northern Clay Center is on Franklin Avenue in the Seward neighborhood of Minneapolis.

O’Krongly recently wrapped up a show at the Northern Clay Center (where she has her studio and also teaches classes) as well as a show in Tennessee. She’s looking forward to deeper exploration of traditional ceramics methods in Cambridge, England, this summer. Just last week, O’Krongly spent some time describing the colorful terminology in her chosen art form.


This is a method of covering a clay surface with a contrasting color of thin clay, then drawing through that thin layer. “It looks like there is a pencil drawing on the surface,” O’Krongly explains, “but it’s actually scratching away the lighter color to reveal the darker color beneath it.”

Photo showing scraffito detail

Much of O’Krongly’s work exhibits the scraffito technique.


The layer of thin clay that is applied in scraffito is called slip. Slip is simply clay and usually other materials suspended in water.


The act of mixing slip is called blunging. The tool that’s used is called a blunger. “I don’t know why it’s called blunging,” O’Krongly laughs. “I guess it could relate to ‘bludgeon’ because you are really beating the heck out of it when you do that!”

the blunger

O’Krongly brandishes the blunger.


Glaze is the glassy substance that is fused onto the surface of ceramics to form a hard coating. O’Krongly says that a glaze mixture — which includes silica, alumina, water and other materials — has a tendency to want to settle out, so artists alter the chemistry of the mixture using a process called flocculating. “What we use to flocculate is Epsom salts, which makes the clay particles stay in suspension,” she explains. “When you’re glazing you want all of the materials to be evenly distributed on your work.

Mixing glaze that's flocculated with Epsom salts

Mixing glaze that’s been flocculated with Epsom salts.


In a ceramics studio, reclaim is also a noun. Simply put, reclaim is recycled clay; the excess clay that runs off a potter’s wheel can be gathered and reused. “We throw all this sloppy, juicy clay into big buckets and then I mix it up with dry materials until it’s back to the consistency of clay again,” O’Krongly says. “The reclaim tends to be one of the nicer clays. It gets better with time.”

Reclaim bucket

Used clay breaks down in buckets like this; it’s mixed with dry materials to form reclaim.

pug mill

A pug mill is the device that extrudes reclaim into neat blocks. The blocks of reclaim can then be bagged, stacked and stored.

witness cones

A digital pyrometer can accurately give the temperature within a kiln at a given moment, but it can’t measure elapsed time. That’s why witness cones are vital. Witness cones are series of spiky clay pieces that are placed inside a kiln. “When you’re thinking about temperature, you also have to think about how long the clay has been at that temperature,” O’Krongly explains. “Witness cones measure both the time and the temperature when they start to curl over and bend.”

a cone pack

Witness cones melt after certain times and temperatures have been reached. A set of witness cones is called a ‘cone pack’.


Witness cones need to be occasionally visible, so kilns have what are called spy holes. To keep heat from escaping, the spy holes are covered with peeps; peeps are removed when ceramic artists want to have a peep at witness cones. “I always think of the marshmallow peeps,” O’Krongly smiles, “but these peeps are usually made of high-temperature ceramic material, often porcelain or brick.”

Peep removed from spy hole

A visible flame surges from the kiln when the peep is removed.


An undesired effect that can happen when firing glazed earthenware is that the clay underneath the glaze shrinks faster than the glaze itself, causing the glaze to flake off the piece; this is called shivering. “Glaze is essentially glass, so you really don’t want glass in your cup of coffee in the morning,” O’Krongly says. “Shivering is probably the worst fault.”


Crazing is the opposite of shivering in that the glaze shrinks more than the clay, creating a network of cracks that permeate the surface of the object. What’s interesting about crazing (versus shivering) is that sometimes it’s a desired effect. “Some people love that look and will actually stain the crazed lines with black ink or something to really bring them out,” O’Krongly says. “They can be very beautiful.”

An example of crazing

The texture on this bowl is the result of crazing.


No circus performer would want anything to do with these. Clay objects that are placed in a kiln must not come in contact with one another or with the kiln walls. Objects are carefully stacked on platforms, and the bricks that separate the platforms are called stilts.


Stilts separate platforms of earthenware objects loaded in the kiln.


This is an adjective that’s used to describe clay that is solid at first, but becomes really soft when it’s manipulated. “A lot of people will take a block of clay and drop it on the floor a number of times and then it’s much softer than if they had just taken it right out of the bag,” O’Krongly says. “That’s thixotropic. I love that word!”

Next Tuesday, visit State of the Arts for words from architecture.