An analysis of voids in ceramics

Abstract

Compression voids caused by the presence of air trapped during the kneading process and given their preferred orientation by paddling are found in cerawics throughout the ceramic sequence with few exceptions. These exceptions in Peisker, Hopewell, and Baeher/Pike sherds may be due to greater pressure exerted on the clay during vessel thinning. The rarity of compression voids in Mississippian ceramics requires another explanation. Paddle and anvil thinning is suggested in Mississippian ceramics by the strong orientation of the temper particles. Mushroom shaped pottery anvils have been recovered from Mississippian sites in the lower Illinois River Valley. In Mississippian vessels there are air pockets whic~1 are only slightly oriented parallel to the vessel walls. This may indicate the use of larger-diameter coils in the construction of Mississippian vessels. The use of larger coils would make a thicker pot, if the coils were not compressed very much, and therefore would not deform the air pockets to any great extent. Drying cracks ~re found in ceramics of all periods but are less common in -Hopewell and Mississippian ceramics, indicating better control over the amount of temper used versus the amount of shrinkage expect'ed in the clay. It is interesting to note that the ceramic type with the most drying cracks, White Hall ware, also was the most abundantly tempered. This may indicate a change in clay resource utilization from the source used at an earlier period . and learning to cope wita a- .moister cl!"iY. Leaching voids are present only in limestone-tempered ceramics and often have some limestone occupying a much larger void. These voids are found in most limestone-tempered sherds. Ceramics from the lower Illinois River Valley have, throughout their history, been formed by coiling and the coil built to walls thinned by the use of paddle and anvil. Other methods of vessel-shaping were products of a combination of individual potters' desires and the culture which produced the potters.