Gum Sandarac Mountants

Gum Sandarac has been used as a mounting medium suitable for material that cannot be cleared with xylene and must be coverslipped from ethanol. Euparal and its green cousin, Euparal Vert, are commercial mounting media that have enjoyed a degree of popularity for this purpose, but their exact formulas have not been revealed as they are trade secrets.

Mohr and Wehrle gave a formula that appears to provide many of the same characteristics. It includes gum Sandarac dissolved in camsal (a mixture of phenyl salycilate and camphor) and includes a terpene, eucalyptol, with dioxane and paraldehyde. A formula published earlier by Shephard does not include dioxane, but is otherwise very similar. Either formula may have a small amount of copper oleate added to the eucalyptol during compounding, in which case the mounting medium will be green and resemble Euparal Vert. Copper is an effective mordant for hematoxylin and preserves the staining of nuclei with that dye.

Formula

Camsal

Sandarac mountant

If the gum Sandarac is dirty, it should be dissolved in absolute ethanol to a suitable consistency, then filtered and dried by evaporation. This should be done under anhydrous conditions i.e. under a bell jar with anhydrous calcium chloride or silica gel.