There is often some confusion about the difference between the most common grades of PTFE, often called Teflon: Virgin Grade, and Mechanical, or Reprocessed Grade. This information will help you understand these two types and their different applications, and therefore save you time researching the information.
Material and applications
PTFE ( polytetrafluoroethylene ) is a type of plastic most commonly known as the brand name Teflon®. PTFE resins have a continuous temperature rating of 260°C (500°F). Mechanical properties begin to degrade above this point.
Both Virgin and Mechanical grades are 100% PTFE material and have similar chemical properties. These are both unfilled types of PTFE. Other types are available with fillers such as carbon, bronze, or glass to improve performace for certain applications.
Mechanical PTFE is an economical, reprocessed PTFE with slightly lower physical properties than virgin grade. It is also referred to as “recycled” or “reclaimed”. Reprocessed material is added during the manufacturing process; usually a small percentage but it varies. It is more economical than virgin. This is the grade used for most applications, for less demanding uses where high purity materials are not required, such as noncritical chemical, electrical, and mechanical applications. It has better wear resistance and compressive strength than virgin grade. Not suitable for food contact.
Virgin PTFE is a higher grade, pure material, and is more expensive. It is made with no recycled material added. It is chemically inert up to 500ºF, the best chemically resistant material available. Virgin has better physical properties and retains flexibility in low temperatures. It is a good electrical insulator, with high dielectric properties. It is FDA approved and is used in the pharmaceutical, food and beverage, and cosmetics industries. It is often used for medical or electrical applications. Virgin has better friction characteristics, which may be important in some applications.
How do you know if you have Virgin or Mechanical PTFE?
Distinguishing between the two grades by sight is certainly not easy! To the naked eye, the two grades may look identical.
Virgin grade is often a purer white when compared side-by-side, and should feel more smooth and slippery.
PTFE is commonly called Teflon®, which is actually a DuPont trademark name for its brand of PTFE resin. Different brand names are used by other manufacturers, such as Fluon ® or Dyneon ®.
If you would like to refer to the ASTM standard, see ASTM D1710 Standard Specification for Extruded Polytetrafluoroethylene (PTFE) Rod, Heavy Walled Tubing and Basic Shapes.
Source by Jeanne Phillips