In the absence of nuclear weapons testing, assuring comparable material performance for replacement of no-longer-available material with modern formulations is difficult. The replacement material must completely replicate the performance of the original. Quantification of morphological characteristics in three dimensions by micro X-ray computed tomography (mu CT) lends statistics and property values not otherwise achieved. This allows for the measurement of lot-to-lot, synthesis formula variations, as well as pre- and post-experimental structural changes that would be invisible to qualitative image comparison techniques. Owing to the unavailability of the original material, several novel formulations of poly(dimethylsiloxane) (PDMS) foams were imaged and quantitatively compared to aid in choosing a replacement material. In this study, bulk properties were measured with mu CT including, percent void volume, average void equivalent diameter and others, and were collected for four different formulations of PDMS foams from pristine, return for service, as well as samples that were aged by gamma ray exposure. Performance characteristics (e.g., Poisson ratio) were measured and compared. From this study, we will be able to provide more information for the selection of the material that most closely matches the performance of the original material.