Rubber Stoppers & Plastic Caps

Rubber stoppers, polypropylene stoppers, and cork stoppers for sealing laboratory glassware, test tubes, and sample containers. SmartLabs stocks solid rubber stoppers, one-hole and two-hole rubber stoppers, polypropylene screw-fit stoppers, and natural cork stoppers in a range of sizes for school, university, and professional laboratory use across South Africa.

Rubber bungs are the standard choice for sealing conical flasks and round-bottom flasks during heating, gas collection, and distillation experiments. A one-hole stopper fitted with a glass delivery tube channels gas produced in a reaction into a collection vessel, while a two-hole stopper supports two separate glass tubes for more complex apparatus such as Kipp's generators and aeration setups. Solid stoppers seal bottles and flasks airtight for reagent storage between uses.

Polypropylene stoppers offer broader chemical resistance than natural rubber, making them the correct choice for storing concentrated acids, alkalis, and organic solvents over extended periods. Cork stoppers allow slow gas exchange and are used in fermentation and biological culture applications where a breathable but protective closure is needed. All stoppers in this range are sized using the standard numbered system and are compatible with standard laboratory glassware neck diameters.