The Navajo Indians, being a semi-nomadic tribe did not develop the art of pottery making until very recent times. Navajo vessels were traditionally heavy and very plain, made primarily for temporary use in water storage and for drums. Navajo pottery vases were tall and almost straight walled except for a light curve. Fired at low temperatures, they were not suitable for holding water and so were coated inside and out with a thick layer of pinon pitch. Drums were made from these vessels by filling them with a certain amount of water for tone and then stretching a hide over the mouth and tightening it. But in the last 25 years the ever-innovative Navajo have begun a fine tradition in artistic pottery. Using the basics of the early pieces and improving the shape, thickness, and firing methods, the Navajo still use the pine pitch to create a beautiful dark brown pottery with smoky whorls of black and red. Other Navajo innovators have adapted the thick walled pitch covered vessel by painting them with traditional religious images and symbols have created a unique and beautiful art form. Other artists have pioneered a hand etched pre-formed pottery vessel using beautiful pastel colors and fine hand etched designs. Most recently a beautiful and artistic innovation in pottery has been to use strands of horsehair in the firing to create vessels with whimsical scribbles of black lines accented by smoky shadows.