Bung - Rubber Bungs

Rubber Bungs

In chemistry, bungs are usually made of hardened rubber. Some chemistry bungs may also include one or more holes so a glass tube or laboratory funnel may be inserted through the bung and into the container or another piece of apparatus. The rubber bung may be used to seal a flask because the user may require the contents to be mixed via shaking the flask or may require that the contents be kept inside the flask and prevented from leaking out. In all cases, the bung keeps the experimentation environment completely sealed so that liquids or gases cannot escape.

Apart from self-made glassware, rubber bungs are rarely used now. They have been supplanted by laboratory glassware which come with standard ground glass joints which allow the pieces to be fitted together easily. Ground glass joints are also much more resistant to solvents and chemicals used.