This type of Pottery work is low-fired and unglazed. The art pieces are burnished with a stone when partially dry, and then painted with a refined clay slip called terra sigillata, or "earth seal." This slip was used by ancient Greek, Roman, and South American Indian potters. After being fired to cone 012 (1550 degrees F), the pieces are placed in barrels with straw and sawdust. The sawdust is ignited from the top and smolders for three to twelve hours. The carbon from incomplete combustion impregnates the porous clay surfaces, causing the white slips to turn black. On some of the pieces there is evidence of a hotter, faster firing, and marks of the flame result from the ignited straw re-oxidizing the black surfaces. Because of the nature of the firing, these pieces must remain porous. They are not designed to contain water, or to resist abrasion by sharp objects which with any art piece this would also be true. These works of art are in excellent vintage condition, and I sourced them from an estate auction where they had no idea what they were, I am pricing accordingly just the mother sells for $1800.00. If you are a collector or reseller enjoy the price.