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, thereby saving you time searching for information.
Material and applications
PTFE (polytetrafluoroethylene) is a type of plastic more commonly known as the Teflon® brand. 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. Both are types of unfilled PTFE. Other types are available with fillers such as carbon, bronze or glass to improve performance in certain applications.
Mechanical PTFE is an inexpensive, reprocessed PTFE with slightly lower physical properties than virgin grade. Also called “recycled” or “reclaimed.” Reprocessed material is added during the manufacturing process; usually a small percentage but it varies. It is cheaper than virgin. This is the grade used for most applications, for less demanding uses where high purity materials are not required, such as non-critical mechanical, electrical and chemical applications. It has better wear resistance and compressive strength than virgin grade. Not suitable for contact with food.
Virgin PTFE is a higher quality 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 remains flexible at low temperatures. It is a good electrical insulator, with high dielectric properties. It is approved by the FDA and is used in the pharmaceutical, food and cosmetic industries. It is often used for medical or electrical applications. Virgin has better friction characteristics, which can be important in some applications.
How do you know if you have virgin or mechanical PTFE?
Certainly distinguishing between the two degrees with the naked eye is not easy! At first glance, the two degrees may appear identical.
Virgin grade is often a purer white compared to side by side, and it should feel smoother and more slippery.
Additional Information
PTFE is commonly referred to as Teflon®, which is actually a DuPont trade name for its brand of PTFE resin. Other manufacturers use different brands, such as Fluon® or Dyneon®.
For the ASTM standard, see ASTM D1710 Standard Specification for Extruded Polytetrafluoroethylene (PTFE) Rod, Heavy-Wall Pipe, and Basic Shapes.