The bulk of my training as a potter was with a native coastal Ecuadorian peasant woman from the Guayas Basin region. This women, Panchita, made her vessels using the most sophisticated hand forming method I had ever witnessed–a technique that is neither coil, pinch pot nor of slab construction. I call it drag-modeling. Starting with a solid cone of clay, the potter places the narrow end down on a wooden board that has been dampened with water, enabling the lump to freely rotate on the board as the potter rotates it with her left hand on the outside. She simultaneously starts to hollow out the solid cone of clay on the inside with her right hand, digging into the cone and dragging the clay upwards and outwards. Note however, that she never removes the clay from the cone, but simply redistributes it. This method of construction is ingenious—it leaves no natural fracture points.
The drag modeling technique of construction stands in contrast to a coil construction method in which each new coil must be joined to the one below it. While the outside walls of the coils are usually joined well by smearing them together, it is the center of the coil that may not be pressed down sufficiently to create a good join, leading to the natural fracture points between coils that have allowed archaeologists to identify this method of construction quite easily.
The shape is perfected and the surface smoothed and polished using only the tools derived from nature – ‘cucharas’ for shaping made from a tree gourd, bamboo knives for rimming and scraping down the walls, and weather worn stones and a sea heart bean for burnishing the vessels. Firing takes place outside in a tee-pee fashion bonfire.
See the video I have posted showing how coastal Ecuadorian potters make their vessels – starting from digging the clay out of the ground to slipping and burnishing- to firing. This video, however, is not just about technique, but how pottery making occurs in the context of village life.
Today, I continue making my vessels using the hand building technique taught to me by Panchita.
However, I decorate my vessels using two pre-Colombian techniques which I have been able to rediscover – an Andean smoke resist technique called “negative painting” as well as “iridescent painting”. Both these decorations are applied to a vessel that has already been fired, thus they are both considered post-fire decorative techniques. The pre-Columbian coastal Ecuadorians apparently specialized in post-fire decorative techniques!
Negative Painting: In the case of “negative painting” a design using a clay slip is painted onto the already fired vessel. Then the vessel must be turned dark brown or black in a secondary very low temperature “smoking” or “smudge” firing not exceeding 300 degrees C.
The layer of clay slip protecting the design underneath must be applied thickly in successive layers, using a brush. It has to be thick to protect the design from the next step: smoking or smudging the pot in order to turn the unprotected areas a dark brown or black. After the vessel cools, the protective coating is removed revealing the design which will be in the original color of the fired clay pot. Sometimes, there will be a bleed-through of the smoke on the edges of the line. This may be considered a diagnostic tell-tale sign of negative painting. It occurs because when using a brush to apply the clay slip, the center of the line will usually be thicker than its edges, allowing the smoke to partially penetrate. The layer of clay slip protecting the design underneath must be applied thickly in successive layers with a brush. It has to be thick to protect the design from the next step: smoking or smudging the pot in order to turn the unprotected areas a dark brown or black. After the vessel cools, the protective coating is removed revealing the design which will be in the original color of the fired clay pot.
However, this effect may also be modified by cleaning up the lines with a stick.
Iridescent Painting: Iridescent painting is also a post-fire decorative technique. I has been definitively shown to be so by Aurelio Alvarez Perez in his analysis of iridescent painted potsherds from coastal Ecuador via scanning electron microscopy (See Aurelio Alvarez Perez (La cerámica arqueológica del Ecuador 1995:409 in Mercedes Guinea, Jean-François Bouchard & Jorge Marcos (coordinadores) Cultura y medio ambiente en el area andina septentrional, no. 21, 1995). While that study clearly indicated the the iridescent paint had been applied to an already fired ceramic, and that it consisted of laminar micro-crystals, it told us nothing about the raw materials and technique used to produce iridescent painted pottery. This latter task fell to me. Not only is iridescent painting a finger painted decoration consisting of bands and dots, but that the paint consists of a watery red iron oxide (ferric oxide or hematite) that also must contain very fine ground up particles of specular hematite, the crystalline form of hematite in order to give the decoration its unusual metallic-like luster. It is the specular hematite that is responsible for giving a unique reddish to silvery patina or luster characteristic of iridescent painted wares. Without the presence of specular hematite, and without a special method of applying the paint shown in the video below, no metallic luster will be attainable.
I have completed a video detailing my hypothesis about how the ancient coastal Chorrera potters were accomplishing iridescent painting, a technique that goes back to about 1000 years before Christ.