ABC of Safety in the Biological Sciences
Units should be tested annually to ensure electrical safety. When sectioning paraffin wax with a melting point between 52 and 54oC a thermostatically controlled water bath at a temperature of approximately 42°C is satisfactory for flattening sections. Water baths should be covered when not in use and water changed frequently to prevent the growth of bacteria and algae, which thrive in warm water and daylight. If necessary a low concentration of thymol can be added to the water to prevent algal growth. Thymol is an irritant and must be handled accordingly. Floating sections on the surface of warm water may create aerosols which can transmit infecting agents from contaminated water. Water baths also become contaminated by tissue particles which can cause artefacts on subsequent sections. All of these problems can be prevented by changing the water frequently.