Cork Stopper, Silicon

Quick Answer: The Cork Stopper, Silicon is a tapered stopper moulded from silicone rubber (the listing spells it silicon). A silicone stopper closes flasks, test tubes and bottles where heat, sterilisation or low odour matters more than solvent resistance.

Silicone Versus Ordinary Rubber

Silicone rubber is built on a silicon-oxygen backbone rather than the carbon chain of natural rubber. That gives it a wide working temperature range, flexibility when cold, resistance to ozone and ageing, and little smell or taste. It is generally autoclavable, which is why microbiology and media preparation rooms favour silicone closures for culture flasks and bottles that go through repeated sterilisation.

The trade-offs are just as characteristic. Silicone tears more easily than natural rubber once nicked, so pushing a sharp-edged tube through it needs care. It is also relatively permeable to gases, which suits a culture flask that needs some air exchange but not a vessel that must stay gas-tight for days. Non-polar solvents such as hexane and toluene make it swell.

For everyday closures where none of these points matter, a solid rubber stopper is the usual alternative, and for oily or weathering conditions the neoprene stopper sits between the two.

Specifications

Applications

• Closing culture flasks and media bottles that are autoclaved repeatedly
• Stoppering tubes kept in a refrigerator or freezer, where ordinary rubber stiffens
• Sealing sample containers where rubber odour or sulfur compounds are unwanted
• Closing glassware in a drying oven, within the stopper’s temperature rating

Care & Handling

• Wash in warm water with a mild detergent; silicone attracts dust and lint, so rinse it thoroughly.
• Autoclave with the stopper loosely fitted, not jammed in, so steam reaches the neck and the stopper does not set in place.
• Keep away from sharp edges and blades; a small nick in silicone spreads into a tear.
• Replace stoppers that turn cloudy, sticky or swollen after contact with solvents.

Why Choose LabEquip

Silicone stoppers are usually ordered by microbiology labs, colleges and research rooms that sterilise glassware often. LabEquip includes them in the General Lab Products range; share the vessel types and neck sizes on the contact page.

Frequently Asked Questions

Is silicon the same as silicone?

No. Silicon is the chemical element; silicone is a polymer made from silicon, oxygen and organic groups. This stopper is silicone rubber, and the product name uses the shorter spelling.

Can silicone stoppers be autoclaved?

Silicone is generally autoclavable and tolerates repeated cycles better than natural rubber. Check the item’s temperature rating, fit the stopper loosely during the cycle and let it cool before pressing it home.

Why does my culture lose moisture under a silicone stopper?

Silicone lets gases and water vapour pass through slowly. That allows air exchange for cultures, but over long incubations it also allows some drying. Use a gas-tight closure if moisture loss matters.

Which solvents should be kept away from silicone?

Non-polar solvents such as hexane, toluene and petrol-type hydrocarbons swell silicone rubber, and concentrated strong acids and alkalis attack it over time. Water, dilute acids and alcohols are generally tolerated.

Does silicone stay flexible in a freezer?

Silicone rubber keeps much of its flexibility at low temperatures, where natural rubber stiffens. That makes it a practical choice for tubes and bottles stored cold.

Can I push glass tubing through a silicone stopper?

Yes, through a bored stopper, but lubricate the glass with water and ease it in gently. Silicone tears more readily than ordinary rubber, and a rough glass edge can start a split.

Last Updated: September 2026