Looking back at the “state of the nation” 60 years ago, World War II had ended. The U.S. economy was thriving. The baby boom era had begun. And 3M invented the first vinyl electrical tape.
This year, the tape that has come to be known as Scotch® Super 33+™ Vinyl Electrical Tape is 60 years old and is the only vinyl electrical tape still made in the United States.
How the tape came to be
Today’s Scotch® Super 33+™ Vinyl Electrical Tape is the 17th version of the best-selling premium vinyl tape in America.
Before vinyl electrical tape came on the market, the most widely used tape was made of tar-coated cotton and a vulcanized rubber adhesive. While this tape provided good mechanical protection, it was prone to rotting, lacked strength and had to be applied over rubber tape to insulate a conductor. And under certain conditions, the rubber adhesive – vulcanized with sulfur – caused corrosion.
In the early 1940s, vinyl plastic emerged as a highly versatile material used in a range of products – from shower curtains and plastic aprons to wire and cable insulation. Early efforts to combine this vinyl with an adhesive to make tape were not successful. But the inventors at 3M persisted.
In 1946, three 3M scientists applied for a patent for a vinyl electrical tape with a plasticizer system and nonsulfur-based rubber adhesive. The first commercially available tape was used for wire harness wrapping. And it wasn’t black – it was yellow. Later versions were white, but white proved to be unstable in ultraviolet light. Because electricians already were accustomed to using a black tape, 3M began to make its new vinyl tape black.
All-around improvements
Today’s Scotch® Super 33+™ Vinyl Electrical Tape performs well, even in extreme temperatures. Increased adhesion ensures that the tape remains sticky, adheres smoothly in low temperatures and does not ooze or melt in high temperatures. The improved backing provides greater flexibility in cold weather and easier handling year-round.
Sixty Years Later, She Knows She Made a Difference
Esther Eastwold was not only an employee at 3M when vinyl electrical tape was invented in 1946. She was the sole woman chemist in the lab where the tape was invented and one-third of the team on the original patent for the new tape.
“3M had a big desire for a tape that was stretchable,” she says. “At that time, any backing that would stretch would destroy the adhesive. I was doing the work on the backing that made it possible to make a stretchable tape. I didn’t have anything to do with adhesives at that time; we used existing adhesives.”
Friction tape, which was used before vinyl electrical tape was invented, was very bulky and didn’t stretch. The new tape, a plasticized vinyl, was conformable and didn’t take up a lot of room. Eastwold was the one who found a plasticizer that would stay in the backing rather than migrate into the adhesive, ruining it.
The official title on the patent application was “Insulating Tape.” It was submitted to the government in January 1946. The patent was not granted until July 10, 1951.
Eastwold graduated from the University of Minnesota in 1943 with a major in chemistry and immediately joined 3M. “All the young men were off to war,” she says. She worked at 3M from June 1943 until April 1951. During that time she met Robert LePage, a young man who would later become a 3M vice president. After they married, she quit working at 3M because, she notes, “It wasn’t ordinary for a woman to have a career and be married, too.” The LePages are retired and continue to live in Minnesota.
She adds, “As a working woman, I was treated very fairly. I never felt at a disadvantage being a woman. I enjoyed working for 3M. I was thrilled at being there.”
Learn more about the history of Scotch® Super 33+™ Professional Grade Vinyl Electrical Tape
