At this stage I do not believe I can create vessels as beautiful as Wayne’s, but I believe that anyone willing to put forth the necessary effort can discover the relationship between the human spirit and the earth spirit. And that, in my opinion, is the ultimate reward.

The more I learn about collecting and processing “found clays” the more I marvel at the patience and skill of early people who produced superior pottery that is light, strong and watertight. It is truly one of the great scientific and artistic achievements of ancient technology.

History

We can only speculate how pottery first came to be, but we can be sure it was the result of a long evolution with many trials and failures. The most primitive vessels of early men and women were their hands—then leaves, bark, shells and sections of plants were inevitably used. Later, the hollowed-out shells of gourds and squash served as major containers for food, especially liquids. By means of these, early people could not only dip water, but transport it from place to place.

We do know that native American pottery has been around since prehistoric times and was manufactured by the sedentary peoples of the Southwest for at least two thousand years.

Three cultural groups, the Anasazi, Hohokam and Mogollon, share the distinction of being among the finest prehistoric artists to have lived on the face of the earth. And of all their known art forms, pottery has best survived the centuries and truly demonstrates the ability of these craftsmen and women. But to fully appreciate these ancient vessels, we must learn the manner in which they were made.

So before you embark on a pottery-making adventure, I encourage you to first visit museums, galleries and exhibitions featuring primitive pottery of various periods. If you can, visit a potter like Wayne, who replicates early cultures. Knowing what has been accomplished before and by others adds value and appreciation to the art, not to mention your own efforts.

Clay Sources and Collection

At long last, my early study of geology has meaning and purpose—in fact, I find almost as much enjoyment locating clay as I do making a pot. And every terrain is now a possible new source of clay, or minerals for temper or paint.

Clay is a soil that comes from sedimentary rock formed by the accumulation of materials at the earth’s surface as a result of the geological processes going on there. It varies greatly in composition, so an understanding of geological strata and soil characteristics can be a great help when you search for local sources.

After millions of years of being acted upon by wind, frost, ice, water, snow, heat, cold and the gasses of the air, the rocks on the surface of the earth break down into various forms.

Plateau formations contain alternating weak and resistant rock layers and layers of clay and shale. Also, in areas where slumping (a landslide where rock masses tilt back as they slide from an escarpment) occurs, thick deposits of sedimentary rocks generally overlie clay or shale. Or you can look for natural flood plains where the valley floor is flattened and broadened by river erosion and floored with deposited sediments. In bends of the river the velocity of the water is slowed and the coarsest material comes to rest nearest the river bed, building up natural embankments or levees along the sides; behind these levees are the backswamps in which the finer sediments are deposited.

Also pay attention to erosion where there are hills and banks; most clays do not erode as quickly as other mineral and earth surfaces and so are exposed. Clay deposits can also occur in rocky areas—in fact, the clay used in Zuni pottery is a dark, bluish clay shale found in layers usually near the tops of the mesas.

When moist, clay holds a particular shape and becomes “plastic.” Deep cracks in the surface of dried soil is also an indication of a degree of this plasticity. Once you locate a likely source of clay, dig a foot or two into the deposit to get a true specimen, then wet a small amount about the size of a marble and roll it into a ball. Flatten the ball. If a sample is sticky and cracks when pressed flat, dig enough to give it a try. But remember, although clays are found widely scattered throughout the earth, some are useful for making pottery and some are not.

For instance, alluvial clay carried into lakes or valleys by rivers is not always good to use for pottery because a lot of organic matter is mixed with the clay. It is better to gather residual clay from fresh road cuts and eroded hills, or along the banks of stream beds. Residual clay was at one time sedimentary clay that has had thousands of years to improve through compaction.

There are three main impurities to watch for when digging for clay: iron pyrite (a sulfide sometimes known as fool’s gold), limestone (calcite), and gypsum (a sulfate). If small white crystals appear on the surface of the raw material, it probably contains gypsum. Gypsum can cause scumming, a white film on red-firing clays. Gold colored particles are usually pyrite. Small pyrite particles cause black spots in reduction firing, larger particles can cause small pop-outs (small explosions that look like rock chips in a car window) during firing. Calcite acts as a bleach on red fired clay turning it a buff color. Large amounts of quartz in the form of sand or silt can also cause problems. Nevertheless, clay that is found having some of these impurities is still usable, depending on the amount of them in the clay.

With a little time and close observation, you will certainly find sources of workable clay—from there you will doubtless expand to experiment with color. Pure clay is white, but most that you find will be colored brown, green or red by iron compounds. Due to weathering, a clay may be one color on the surface, and another at deeper levels. However, if the clay is the same both on the surface and at the inner depth, it is probable that it will also fire true. Mixing clay is not recommended, although some potters do it. The most common colors in raw field clays are gray-green, dark brown, reds and gray, but it is almost impossible to determine the fired color of the clay as it is found on site.

Be aware, too, that the color of the clay alone is not always responsible for the fired color. Pots that are oxidized in firing will be brighter in color as a result of the oxygen that completely burns the fuel, opposed to the black or gray cast that results from soot, smoke, and reducing gases that exist in reduction firing.

It is helpful to label your clay samples. I have several buckets of red and gray clay specimens which have proved excellent for pottery, but unfortunately I did not note their location. I have since learned to tie a small tag to the handle of the clay bucket to indicate specific locations. For even better identification, after the specimen is processed I make a tile about half the size of a bathroom tile on which I also code the clay source. Then, on a piece of cardboard I trace an outline of the tile before it is dried and again when dry to measure the amount of shrinkage. After the tiles have been fired I measure the tile again for additional shrinking and note color changes. In this way I am able to weed out unsuitable clays from those that I want to use again.

Clay Preparation

After you collect your clay, the next step is to dry and clean it of large, obvious sticks and rocks, then crush or grind it. This was originally done with a special mano (grinding stone) on a metate (grinding surface).

One cleaning method used by the ancients was accomplished by winnowing the dry clay like wheat to oust small pebbles and fine gravel, either of which will ruin a pot if not removed. The larger impurities are, of course, picked out by hand.

Another way to prepare small clumps of clay is to put them in a container, such as an enameled basin, a bucket or large (fired) bowl, and add enough water to saturate them. Once the clay has been thoroughly softened with water you can remove the pebbles by squeezing and kneading it.