Critical point drying is a sample preparation technique that minimizes damage to some clay fabrics in reservoir rocks. In this technique, the original pore fluids in a sample are replaced successively with acetone, liquid carbon dioxide and air without allowing a high energy meniscus to pass through the sample. Acetone replacement is accomplished in a diffusion dehydration system. SEM micrographs show striking differences between critical point dried clay samples and air dried samples.
Wawak, B. E. and Campbell, W. L.
"Characterization of Clay Fabric using Critical Point Drying to Preserve Clay Texture and Morphology,"
Scanning Electron Microscopy: Vol. 1986
, Article 9.
Available at: https://digitalcommons.usu.edu/electron/vol1986/iss4/9