The speckled appearance of some of the abraded surfaces suggests the use of pulverized potsherds, a practice frequently resorted to by the modern tribes. In some localities, notably in the south, we find a slight admixture of mica, which may have come from the use of pulverized micaceous rock.
CONSTRUCTION.--No one can say just how the materials were manipulated, fashioned into vessels, and baked; yet many facts can be gleaned from a critical examination of the vessels themselves; and an approximate idea of the various processes employed may be formed by a study of the methods of modern potters of the same region or of corresponding grades of culture.
It is evident that the vessels were built and finished by the hands alone; no wheel was used, although supports, such as shallow earthen vessels, baskets, and gourds were certainly employed to a considerable extent. Primitive processes of building have varied considerably. The simplest method perhaps was that of shaping a single mass of clay by pressure with the fingers, either with or without the assistance of a mold or support. The mold would be useful in shaping shallow vessels, such as plates, cups, and bowls. The walls of vessels of eccentric forms or having constricted apertures would be carried upward by the addition of small more or less elongated masses of clay, with no support but the hand or an implement held in the hand. Casting proper, in regularly constructed molds, was practiced only by the more cultured races, such as the Peruvians. A variety of methods may have been employed in the construction of a single piece.
SURFACE FINISH.--A great deal of attention was given to surface finish. In the coiled ware the imbricate edges of the fillets were generally either smoothed down and obliterated entirely, or treated in such a way as to give a variety of pleasing effects of relief decoration. Vessels with smooth surfaces, whether built by coiling, modeling, or molding, very often received a thin coat of fine liquid clay, probably after partial drying and polishing. This took the place of the enamels used by more accomplished potters, and being usually white, it gave a beautiful surface upon which to execute designs in color. Before the color was applied the surface received a considerable degree of polish by rubbing with a suitable implement of stone or other material. Attention was given chiefly to surfaces exposed to view--the interior of bowls and the exterior of narrow-necked vases.