The process of dewaxing has often been thought of as a black art. The de-waxing process varies from foundry to foundry due to wax formulation, shell process, and even the autoclave design. The de-waxing process is related to the causes of shell cracks and is a subject of continued investigation. If the dewaxing process could be modeled, taking into account process variables, autoclave conditions could be altered, shell modifications could be made and pattern designs could be changed to help alleviate shell cracking. In order to develop a valid theoretical model of the dewaxing process, moisture, pressure, and thermal data need to be gathered from various production autoclaves. An encapsulated, portable data acquisition system for use in production autoclaves was designed, built, and tested. This device has been successfully used to capture data on real production autoclaves at participating foundries.