Indian pottery making in the village of San Ildefonso, New Mexico

This film depicting the unique process of pottery making at the San Ildefonso Pueblo was made by George Clyde Fisher, curator in the AMNH Department of Education, Clark Wissler, curator-in-chief of the AMNH Department of Anthropology, and Kenneth Chapman of the Laboratory of Anthropology in Santa Fe, New Mexico Renowned potter Maria Martinez demonstrates the technique of her unique method of firing pottery. Before starting, she tosses blue cornmeal over the earth as a blessing. She and husband Julian then remove the clay to crush and winnow it and Maria adds grey sand to the clay to help distribute heat evenly through the final piece when it is fired. The next sequence of footage follows Maria through the stages of forming a pot. The clay is moistened and rolled into rope-like strips. These strips (measuring about 3/8 of an inch in diameter) are coiled on a base-like potter's dish, which is made of wood or basketry. When the vessel takes shape, the coils are pressed together by using the thumb and fore-finger; smoothing of its inner and outer surfaces is accomplished with a gourd spoon. When the pot is almost dry, it is covered with a red earth clay slip. After the drying process is completed, the pot is polished with a potter's stone. Julian collects yucca leaves, which he uses to make a brush for painting designs on the pot. The mineral paint Julian uses is composed of a mixture of guaco vegetable gum, white earth, and water. Once the vessels are shaped and painted, they are inverted and piled beneath pieces of sheet metal over a slow-burning fuel (in this case, cow dung). The film's captions explain that the pottery of San Ildefonso derives its famous black color from carbon: the coloring is said to be created by adding fuel at a certain point during firing, and smothering the smoke so that the carbon is fired into the clay. However, the latest scientific data suggests that when the fire is smothered, the oxygen is pulled from the iron content in the clay, thus causing the clay to oxidize and blacken.