1967 Preliminary reconnaissance of ceramic raw materials suitable for use in a 'cottage industry' or in school pottery courses

Abstract

In this preliminary reconnaissance carried out November, 1966, a number of clays and other ceramic raw-materials were sampled and tested from in and around Darwin itself, from the Gunn Point-Koolpinya area, from the Rum Jungle Complex, and from Oenpelli. The samples were given a series of tests with the aim of disclosing their salient features when used in the development of pottery as a 'cottage industry', or in school pottery and modeling classes. This initial testing programme cannot, of course, provide final or exact indications as to the nature and extent of the formations, as the small hand-samples tested are unlikely to represent accurately the body of material to be worked Secondly, the samples were too small for a conclusive run of tests to be made, and, thirdly, the techniques used will probably need to be modified in the light of the characteristics disclosed However, it is felt that these tests do indicate the broad characteristics of the materials. In some cases the figures given for drying and firing shrinkages or other data will be found to he at variance with those given by the CSIRO for the same formations, the differences may often be accounted for by the differing conditions of testing. The linear drying shrinkages given in this report, for example indicate the shrinkage between normal consistency when used for throwing, and bone dry. Linear firing shrinkages and apparent porosities are given, again, for the usual firing conditions and finishing temperatures used by artist- potters and in schools. These often vary from industrial standard testing procedures. Workability of the material in plastic condition has been assessed in terms of throwing, as it is felt that this is the best forming method to introduce under the circumstance. Conclusions about the usefulness of the materials for the purposes that the Welfare Branch has in view, and recommendations, therefore, are likely to differ from previous findings. The conclusion is that while some satisfactory material exists, the three main problems are difficulty of dispersion in water, splitting and the development of fire-cracks and brittleness in the fired material.