ABSTRACT
Degassing apparatus is made up of a vacuum chamber with a mercury manometer that is connected either to a vacuum pump or to the atmosphere. The vacuum chamber commonly used is tubular, but any shape may be used according to sample size. The sheath containing the segments is taken out of the tube and placed in a deep freezer during the estimated duration of the injection, in order to block the process of cross-linking of the casting agent, i.e., the process of hardening. In the absence of empirical measures of the speed of penetration of the casting agent in calibrated vessels, the durations of injection have been calculated on the basis of the Hagen-Poiseuille law applied to the following two cases. The pigments are visible in the transparent elastomer under transmission light microscope. Thus, their accumulation allows us to locate small perforations traversed by the elastomer but not by the particles.
