More Resources

Note: This section contains five pages. Go to Page 1 - Page 2 - Page 4 - Page 5.

Books

Hands on Clay: An Introduction to Ceramics by Charlotte Speight and John Toki Buy now...

The Potter's Studio Clay and Glaze Handbook: An Essential Guide to Choosing, Working, and Designing with Clay and Glaze in the Ceramic Studio by Jeff Zamek Buy now...

Clay and Glazes for The Potter by Daniel Rhodes

Primitive Pottery by Hal Riegger

Alternative Kilns & Firing Techniques: Raku, Saggar, Pit, and Barrel by James C. Watkins Buy now...

Hand Building Techniques by Joaquim Chavarria

The Complete Potter's Companion by Tony Birks

Handbuilt Pottery Techniques Revealed: The secrets of handbuilding shown in unique cutaway photography by Jacqui Atkin

Websites

Where does clay come from? by Jenny Gulch

Clay's important features by F.H. Norton

Photo of clay rock deposit

Principal Clay Types Used in Ceramics
Hammill & Gillsepie

Clay and Ceramics Info
Clay Times

Clay minerals

Raw materials dictionary
Sheffield Pottery

Watch how feldspar weathers into clay particles video

Digging up and creating pottery with your own clay
eHow
video

How to Make a Pinch Pot video

How to make a casting slip
Laguna Clay

Terra Cotta Slip Casting Recipes
DigitalFire.com

Things to remember about Coil Pots

Clay coiling tutorial

How to use an extruder
GlynnisLessing.com

Create Your Own Homemade Foot-Powered Extruder
Ceramic Arts Daily

Introduction to pottery making

A Photographic Tour of Firing Pottery (using the open fire method)
NativeTech.org

The art of ceramics
NALIS

Learning to Throw Pottery
Marvin Bartel

How to make pottery

Cat Litter, Antacid and other non-traditional glaze materials
Ceramics Today

Make Pottery Glaze with Simple Household Chemicals
ehow.com

Kiln Firing Chart (PDF)

Cone Temperature Chart
BigCeramicsStore.com

Pyrometric Cone Charts

Pottery and Ceramics

Continued from Page 2

Photo: The Cobblestone Muse

Step Three: Wedge, Shape and Sculpt the Clay

For definitions of terms highlighted below, use the ceramics glossary.

Once you're ready to shape your clay body into pottery and other ceramics, retrieve a clump of the prepared clay you want to use and start wedging. Wedging is the act of kneading, slicing, twisting, squeezing, squishing and otherwise mixing your clay body to disperse moisture evenly and remove air pockets. The simplest method is taking a chunk that's about the size of two or three softballs, and squeezing it on either side while rocking it back and forth on a hard surface. As your rock, you rotate the clay a little bit so all of it eventually touches the hard surface. The trick is not to fold the clay, or allow any air pocket slip into the chunk. At the end of the wedging you should end up with a solid cylinder of clay ready for the wheel or hand building. If you're not using it right away, store the clay in a plastic bag or container that locks in the moisture.

Many potters nowadays buy pre-moistened clay, so they can skip the wedging step and get right to work. You won't have that luxury in a post-doomsday world, but it's generally what you'll be using in a ceramics class. Even then, you'll still want to watch out for hard lumps, air pockets and unmixed pockets of sand, grog or other tempering materials in the clay. Unequal weight distribution, lack of consistency, and an excess of organic material in a clay body can cause breakage, buckling, sagging, or holes once the clay is fired.

While most pottery today is "thrown" on a wheel, in a survival setting you'll probably start out with hand-building and the press mold techniques described below. Wheel throwing is described on the next page. Since most community colleges and recreation centers offer ceramics classes, you should take advantage of this training before the inevitable budget cuts of the future eliminate these programs.

Pinch Pots: This is how students get introduced to pottery techniques. Roll a smooth, symmetrical ball of clay, then stick your thumb into it to hollow it out. As you hold the ball in your other hand, you can feel your thumb as it gets close to the bottom. Now use the thumb and three fingers (from the same hand) to create walls of even thickness.

-- --

Making a pinch pot. Photos: Jenny Gulch Pottery

The trick here is to always brace the wall on one side with your fingers while pressing the clay into shape with your thumb. Start shaping the walls near the bottom of the pot and circle around the hollowed opening. In effect, you "pinch" the clay into the shape of a pot. You'll slowly move upwards, pinching the walls until you reach the top .

Once you have the general shape established, pinch out a base (bottom), like the one you see on most pottery. Next, you'll need to smooth out a sturdy lip at the top. Pinch pots work well for containers with thick walls, like coffee mugs, bowls, vases and candle holders. (Adding handles and other features will be discussed a little later.)

--

The paddle and anvil technique. Photos: Left/Alvin and Nadine Lynn. Right/ CeramicArtsDaily.com

Using your thumb and three fingers to make a pot translates on a larger scale to the paddle and anvil method of hand-building. Here a wooden paddle shapes the wall as a rounded smooth stone directs the force of the blow. The stone also maintains the stability of the surrounding area, which allows you to put more muscle into the effort.

Slabs: Another way to construct simple geometric objects, including boxes, is with clay slabs. Today, rolling machines allow potters to slam out big pieces of real estate to work with, but you can use the more traditional pie dough rolling method, or just spread out the clay with a potter's rib (which has a straight edge for leveling surfaces) or your hands. Then you can piece slabs together to form pots or other objects without having to worry to much about plasticity.

- -
Building with slabs. From left, rolling the slab, construction and attaching two sides with slip. Photos: Left and Right/Beth E. Peterson, Middle/Catttaraugus County Arts Council.

With slabs, getting the symmetry right on round objects is more challenging than with other forming methods. Success on a good eye and maybe a template, if you can round one up, so to speak. After you connect the slabs together, it's possible you'll need to reinforce the seams and corners by pressing clay patches over them.This is especially important on round forms when the clay body isn't plastic enough to bend well.

In the case of corners, as well as seams like the one in the far right photo above, or you'll probably want to use slurry to cement the two sides together. Slurry is a thick paste made from your clay body and a little water, with sand or grog added for extra strength. See "Handles, Spouts, etc." below for more on slurry.).) As you continue working on the walls of your piece, be sure to fill in any cracks or craters that develop, and beef up areas lacking in thickness. Then smooth out the walls on the inside and out, so everything looks even and balanced and the walls equally thick all around.

For big jobs, potters roll out big slabs, then cut out several walls or pieces of clay at once. You can also fabricate a "cookie cutter" to really speed things up.

Cutting shapes from a slab. Photo: Megan Chaney Studios

Coiled Pots: Coiled pots look easier to make than they are, but the technique is practiced the world over, so learning the skill is worth the time and initial struggles. Coiling allows you to build bigger and faster than a pinch pot, and get rounder, more symmetrical shapes, plus a variety of profiles and thinner walls.

First, roll one or more clay tubes (i.e. coils) on a flat surface. Between an eighth and a half-inch are typical coil diameters for the average pot. After rolling the oils, enclose each in a circle or hoop and stack them one on top of the other. This will give you the rough form of your pot. So long as your coils all have the same diameter, your walls will have the same thickness.

Working up from the bottom, press the coils snugly into one another methodically, as shown in the left photo below. The higher up you build, the more likely your walls are to buckle or collapse. To get around this problem, stop building after every few coils and let the walls stiffen before climbing higher.

To get a convex shape for a pot bottom, make a press mold of that section on a finished pot (or other similar shape in nature), then start building your coils on top of it after it dries.

---- ---

Forming pottery through coiling. Photos: Left/Lakeside Pottery. Right/Michael Kline.

Unlike pinch pots, by adding coils that slowly increase in diameter, you can get a shape that widens outward. By gradually reducing the size of the coils, you can make the pot slope back inward. In either case, set the new coil onto the one below it so it's sticking out a little over the inside edge if you're reducing size, or a little over the outside edge if you're expanding the pot. (In the video shown below, the potter adds coils on the inside or outside to adjust the wall diameter.)

Nowadays, you can expedite your production of coils by using an extruder. This simple mechanical aid operates on the same principle as a cake-decorating tube. Another big advantage extruders is that you can produce one long coil of clay and build a pot quickly by spiraling it upward like a cobra.

-- --
A home-made extruder. (1) The unit mounted on a wall. (2) Four choices of dies set in an attachable jig. (A screen is added to block three of the four holes during the extrusion.) (3) The plunge/lever (long blue bar) is lifted to push the clay down through the chosen die. Photos: GlynnisLessing.com

The basic goal of extrusion is to push clay through a shaft, at the other end of which lies a die containing a round, square or other type of opening, like the ones in the center photo above. Out from the die "extrudes" the clay. Dies can be cut out of metal, wood, stone, plaster or clay in a myriad of shapes and diameters. The clay body is pushed down through the die with a crank or plunge (shown in the right-side photo above). It's designed to give you leverage, thus minimizing the force needed to push the clay.

Adding Handles, Spouts, Lids, Legs, etc: Learning how to attach a handle to a mug, or a spout to a pitcher is as important as shaping the pot itself. After all, if the attachments break, the item won't be much good to anyone. Potters connect these protrusions with slurry, a runny mixture of coarse clay and water, with sand or grog added to provide extra strength to the joint. To make this cement work, however, it's essential that you score the two surfaces with little crisscross marks in order to create extra areas for the slurry to be inserted between the joints. Spread the slurry witha brush, then press the leg or other protrusion firmly to the object.

Attaching legs with slurry (aka slip).

And now for the bad news about attaching protusions: In a primitive open-fire type firing, it's a rare thing for any to emerge in the same condition as the rest of the pot. Protrusions usually don't share the same heat distribution during the firing. Either they don't get enough heat for the clay to mature or they get too much heat and start to slump or melt. Either way, the joints routinely weaken and fail. That's why you don't often see handles, legs and spouts on primitive pottery. Other design solutions are employed instead, like the one shown below.

- -

At left, a traditional pottery design with no protrusions that might break in an open fire. The narrow bottom and top, combined with a fatter chest, make it easy to grab the pot, pour from it and allow it to sit firmly on a surface with a high center of gravity to minimize tip-overs. An extra coil of clay is typically added to a pot's bottom to cope with wear and tear, and also to provide extra strength where the side wall is attached. At right, a coiled pot made by the author (6 inches in diameter, 3 inches high). This grayish-green clay was dug from a creek bank and mixed with a little ball clay to add plasticity. Until it's fired, this type of clay object is known as greenware. Photo/left: Pottery-magic.com

Molds: Using a mold incorporates a range of techniques, but the general idea isfill the cavity (or positive space) of a solid object (i.e. the mold) with clay. The clay then is allowed to dry long enough so that it becomes stiff enough to handle without losing its shape. For example, if you want a slightly rounded bottom for a coiled pot, you can press some clay around an existing object that approximates the shape. This is known as a hump mold. Alternatively, press some clay around the bottom of another existing pot, gourd or even the inside of a tree stump to replicate those shapes.

A round hump mold is used to shape a new pot. Photo: CeramicArtsDaily.com

Because clay sticks to whatever it gets pressed to, you may need to insert a large leaf, some grass, a plastic bag or other very thin and unobstrusive material around the mold before you get started. Then press the clay firmly into or onto the mold. This type of procedure, which takes advantage of negative space, is called a press mold.

To replicate an existing ceramic object that you like, you can press fresh clay against it or around it and then wait a few minutes (or an hour) for the clay to stiffen. Then carefully remove it from the mold. Once it's fired, your new mold will allow you turn out the same object over and over without all the time spent originally in forming it.

- - - - - -

Forming a clay ornament using a press mold. Photos: TheEnchantedGallery.com

When it comes to bulk producing clay objects, molds are the way to go. Modern ceramicists rely heavily on plaster molds, into which they pour a liquid concoction of clay. The process is known as slip casting, and the liquid clay is called casting slip. While not available to potters operating under primitive conditions, the principles of slip casting have a broad application, so are worth learning.

Besides clay and water, the casting slip requires a third ingredient called a deflocculant. That's because of the slip's tendency to settle. After being poured into the mold, gravity causes the clay particles to sink as they clump together, leaving the water to rise to the top.

A slip mold creates a positive space for pouring a more fluid form of clay called casting slip. Photo: Open3DP

What's needed is an electrolyte (in the form of an alkali) that prevents the particles from "flocking" together, thus becoming heavier than the water. The electrolyte causes them to repel each other instead of attract. (In chemistry, the process at work here is called electrolysis.) The most common deflocculant is sodium silicate (aka water glass), which is no picnic creating on the fly. (It can also be used, incidentally, under different circumstances as a flocculant.) Historically, soda ash (aka sodium carbonate) was used. While the soda adds to the clay's plasticity, it's considered a little too caustic and may start chewing up your mold. You can also try potash or sodium salts (from sodium or ammonium). Besides their electrolyte function, deflocculants significantly reduce the amount of water needed in slip, which in turn reduces the amount of shrinkage to expect when the clay dries inside the mold. In any case, electrolytes should make up no more than 1.5 percent of the weight of the clay.

As for creating the mold, you can use whatever you've got handy to build it, including clay. In a typical scenario, a pot or container is set up with mirror molds. After stiffening, the two clay halfs are cemented at the seams with slurry.

- - -

On left, a typical set of hand-shaping tools includes a loop tool (aka pear pitter) for hollowing out clay, sculpting tool (center, all wood), ribbon tool for shaping, pin tool for scrolling and making holes, wire cutter with handles for slicing slabs and trimming, potter's rib for carving and shaping, a burnishing ttol (top left), and a sponge. On right, scoring with a pin tool. Photos: Left/Amazon. Right/Pinky's Pots

Step 4: Burnish and Decorate

Before firing a clay pot or other form, you'll want to add some finishing touches. This includes sanding the walls of the object to remove any sharp or rough edges, smooth corners and lips, adding a layer of slip and decorating the piece.

In ceramics, the correct term for sanding is burnishing. Many potters use a smooth stone or bone to sand the walls once the clay object dries enough to become leather-hard. Burnishing evens out all the little lumps, so that the surfaces look polished and any iron particles in the clay recedes. Like wood sanding, burnishing leaves a smooth outer layer ready for a slip paint or other decoration.

Clay slip is simply a watery mixture of the same clay used to make the object. Metal oxides are added (cobalt, copper, etc.) to provide permanent color. When making slip paint, be sure to remove any coarse particles which could make the slip gritty. In fact, the best way to avoid that problem is to skim off the top layer of the raw clay body during the settling process. Reserve this fine-particle layter for slip-only duty. (See Page 2 for info on making clay.) It's also possible to prepare a slip from another type of clay, so long as its firing properties are similar to the original clay body. When you mix the clay with water, it should be just runny enough that when you dip a finger into the slip, it emerges with a thin, silky-smooth coating.


The author's work from an introductory ceramics class. The pyramid and two blue objects have been glazed and fired. The red bowl is painted with colored slip and ready for its first bisque firing. The pitcher started out as a slab of clay fastened around a glass vase, then allowed to stiffen. Removed in two halves, the edges were fastened together by scoring and adding slip, which acts like glue. Notice the crack in the pyramid. It developed when the overly dry clay was painted with a wet color slip. Coloring with slip is best accomplished during the leather hard stage.

By adding color, you can also use the slip as a decorative paint. Pigments are typically sourced from metal oxides, since theses last a lot longer than colors derived from plant materials. The primitive name for an oxide pigment is ochre. The best known down through history, of course, is red ochre, which is made from iron (or rust, to be exact). Other popular ochres are extracted from cobalt (blue), copper (green or blue green), chrome (green), and manganese (brown or black). The powdered oxide is simply mixed into the slip to produce paint.

If for some reason the pigment you use doesn't mix well with water and clay, you can first mix it with a binder, then add that to the slip. Binders are a familiar part of oil painting, who use linseed oil for that purpose. However, a more primitive technique is better suited to pottery, utilizing a gum (like gum arabic), which is extracted from plant stalks, then cooked to make a syrup. This syrup disperses the pigment evenly. By adding a little feldspar (if you have it), your slip should survive the firing schedule intact.

Potter Gary Jackson slip paints a mug.

When decorating an object, never use any form of sealer before firing, since that will prevent the escape of water vapors and potentially cause your pots to explode. As a rule, glazing (which seals and waterproofs ceramics) is done after the clay has been fired. (See Page 4 for more on glazing.) And unless you'd like to blow up your kiln, never use petroleum-based paints on pottery.

Besides color, there are more practical matters to consider during the burnish and decorating stage. For example, if you're crafting a pot for fetching water from a river, you'll want to add some texture on the lower exterior walls to make gripping it when wet a lot easier. Potters use either a kitchen fork or a pin tool to create repetitive lines. A crisscross pattern is ideal for making tread.

Just remember, if food or water will be touching a clay surface, you don't to be contaminating it with paint or other toxic substances. As a rule, interior surfaces should be kept free of paint, unless you're sure the paint ingredients are safe.

Finally, keep in mind that heating will likely alter the original color. That's why test firing a few tiles before starting your paint job is highly recommended. As explained in the next section, you can also manipulate an object's color by creating a reduction atmosphere inside your kiln.

- - - - - - - - - - - - - - - - - - - - - - - - - -

Continued on Page 4... (Wheel Throwing)

- - - - - - - - - - - - - - - - - - - - - - - - - -

Return to: Mega-Disaster Planner

- - - - - - - - - - - - - - - - - - - - - - - - - -

Copyright 2009-2014 The City Edition

Home | Survival |Food | Medicine | Evacuation | Disaster Monitoring | 2012
TheCityEdition.com

Optional Index:

Pottery & Ceramics
Carpentry
Chemistry
Leather Work
Basic Mechanics
Raw Materials
Blacksmithing
Housing Construction
Sewing & Cloth
Flintknapping
Mineral Prospecting