46 ABORIGINAL POTTERY OF EASTERN UNITED STATES [eth.anx.20 



recently deposited uUiiviuI sediments. Clean elavs were, however, 

 diligently sought and generally procui'ed,- and in many cases they seem 

 to have been carefully prepared l>y pulverizing, washing, and knead- 

 ing, as was observed by Dumont and others. Finely prepared washes 

 of clay were made for surface finish. Clay unmixed with any kind of 

 tempering was sometimi's used for modeling vessels, pipes, and some 

 of the less important articles. The mor(> advanced potters used j^aste 

 having degrees of refinement suited to the nature of the object modeled. 

 Utensils to be used over tire were tempered with coarser ingredients. 



Temperini; Materials 



Great diversity of tempering materials is observed. This diversity 

 is due to the multiplicity of mineral products brought within the 

 range of experiment. It is apparent that many materials were suited to 

 the purpose. The choice of a single material, where many abounded, 

 must have been due to accident in the incipient stages of the art. It is 

 not uncommon, ho-wever, to find several substances used in the work 

 of a single community — or what appears to be such. The ingredients 

 varied to some extent also with the uses to which the vessels were to 

 be devoted. They include pulverized rocks and mineral substances of 

 many kinds, powdered shells of mollusks, powdered potsherds, and per- 

 haps cinders, besides ashes of bark, sponge, and the like. Raw vegetal 

 substances were also used, the fibrous parts l)eing broken or pulverized. 



The advantages to be secured by the introduction of foreign par- 

 ticles into the day may be somewhat diverse. It is fair to assume 

 that tempering was intended to impart some quality or propei'ty to 

 the paste that the pure cla^' did not possess to the desired degree. In 

 building vessels the clay may have been handled with greater facility 

 through the introduction of sand, but this could not be true of the 

 addition of coarse, sharp particles of shell or crystalline rock; their 

 presence must really have added to the difficulty of shaping and finish- 

 ing the vessel. 



Tempering may have served a useful purpose during the drying and 

 baking of the claj'. It is well known that pure clay has a strong ten- 

 dency to shrink and ci-ack in drying, and it is readilj' seen that the 

 particles of tempering material would in a measure counteract this 

 tendency. The coarse particles would interfere with the progress of 

 the parting movements; the vmdulations that sepai'ate tiner particles 

 with ease would produce no eti'ect. The progress of a crack would l)e 

 impeded, just as a fracture in a glass plate is stopped by boring a hole 

 at the extremit}' of the flaw. It would thus appear that even cavities 

 in the paste serve a useful purpose, and that sawdust and cut straw, 

 even if reduced to ashes }\v firing, would have performed in a way the 

 functions of tempering. In a tine-grained paste the flaw would, when 



