Stoppers and corks are used in laboratories to securely seal vessels. Laboratory stoppers are used not only to prevent spills, but also to trap noxious fumes or to allow the vessel to be shaken.
Laboratory stoppers differ from consumer stoppers both in the variety of sizes specified and in their possible resistance to application hazards. The variety of vessels available in a laboratory mean that over 20 different cork and rubber stopper sizes are available. Green neoprene stoppers are favored for chemical resistance, while red and white silicone stoppers are ideally suited for high temperature applications.