Closures

Plastic Closures

There are two basic types of plastic closures used for scientific applications: thermoset and thermoplastic
Thermoset closures cannot be remelted after they are formed. They provide the widest range of chemical compatibility and they exhibit the most tolerance to temperature of all plastic closures. Because thermoset closures are rigid, they provide the most consistent adherence to close dimensional tolerances. Common resins include urea, phenolic, and melamine.
Thermoplastic closures can be remelted after they are formed. They are known for good impact strength, cost effectiveness, and pliability. Common resins include polypropylene (autoclavable) and polyethylene.

Closure Size Info

Screw thread closure sizes are expressed in two numbers.

The first number specifies the diameter of the closure in millimeters and the second number represents the GPI thread finish.

For example, a neck size of 13-425 has a diameter of 13 mm and fits a container with a 425 GPI thread finish.

Common Cap Finishes