In 1969, Gore was researching a process for stretching extruded PTFE into pipe thread tape when he discovered that the polymer could be "expanded" into a porous form of PTFE, characterized by extremely high strength and porosity. He and others had attempted to stretch rods of PTFE by about 10%. His discovery of the right conditions for stretching PTFE was a happy accident, born partly of frustration. Instead of slowly stretching the heated material, he applied a sudden, accelerating yank. The solid PTFE unexpectedly stretched about 800%, forming a microporous structure that was about 70% air.