An apparatus and method for obtaining core samples from a wellbore includes bringing a substance (3) into contact with the core sample. The substance (3) is adapted to retain at least a portion of fluids recovered with the core sample. A receptacle (2) such as a core barrel (2) contains the substance and is inserted into the wellbore and receiving the core sample in the receptacle (2). The substance may be sealed in the receptacle by a dissolvable plug mechanism (10). The substance (3) is transformable between a highly viscous state and a substantially solid matrix.