The evolution of Eastman materials. Tenite to Trēva and Tritan in Ophthalmics

In this globally branded era, it is unusual to find a product that is such a fixture of American life yet remains so relatively unpublicized and humble.

However, if you’ve worn Ray-Ban sunglasses, used a Craftsman screwdriver, or written with a Bic pen, it’s likely you’ve used Tenite™ cellulosics, a polymer that is one of the cornerstones of America’s product design history.

Since its first introduction by Eastman in 1929, the versatile, durable, and attractive material has been used in thousands of consumer products, from radios and telephones to toothbrushes and toys, and is still commonly found today.

Derived from a natural raw material — the fast-growing softwood trees of the southeastern United States — the material’s selling point is the way it feels to the touch, says Rob Wagner, former product manager for Cellulosics Plastics.

An enthusiastic documentarian of company history, Wagner has worked at Eastman’s Headquarters in Kingsport, Tenn. since 1987 and now serves as its senior global capital procurement manager.

“The applications that have done really well with Tenite were basically all things you can touch,” he says. “To quote the designers who work with us, ‘It feels very warm and natural — because it is.” The polymer in nearly every pair of Ray-Ban Wayfarer sunglasses is likely the same as in Craftsman screwdriver handles.” The story of this fascinating material began just after World War I, when George Eastman, the founder of Eastman Kodak (as the company was named then), needed photographic chemicals.

“Originally, they had come from Germany, but after the war, he started looking for other ways to source methanol and other chemicals because the country was essentially in ruins,” says Wagner.

Eastman created his own, eponymous chemical company in Kingsport, taking a major role in the growth of the town.

Although the population in 1920 was just 5,700 compared with 53,000 today, there was a ready supply of labor and softwoods to make cellulose, which was (and still is) the basis for many photographic chemicals. The market was hungry for these products, and the company grew in leaps and bounds.

By the 1920s, Eastman was venturing into other fields. After a series of disastrous fires in turn-of-the-century movie houses caused by cellulose nitrate film stock (also known as “guncotton”), the burgeoning Hollywood movie industry replaced it with Eastman’s fire-resistant cellulose acetate, more popularly known as “safety film.”

The big leap forward came when Eastman scientists discovered that they could not only extrude cellulose acetate but mold it into useful shapes.

In 1932, the Tenite brand name was launched, using a portmanteau combining its birthplace, Tennessee, with a popular suffix of the era: “-ite.”

The product became a major player in the emerging industries of the booming postwar economy — the automobile explosion, for example — and shaped many of the products created during that time. Some of the first football helmets were made from Tenite, as were the first Lego bricks and the first View-Masters. On any given day during that era, it was virtually impossible not to encounter the product, says Wagner.

“Between 1930 and 1955, Tenite reached its zenith,” he says. “At one time, every automobile steering wheel, gear shift, door button and dash control knob was Tenite. For 20 years, many telephones made in the United States came from Tenite, as did Craftsman screwdriver handles, casino playing cards, and Bic pens. Even Scotch tape is made with our cellulose acetate.”

From medical aid to fashion accessory

Meanwhile, another industry was growing in Southbridge, Mass., where the American Optical Co. had set up shop in the mid-1800s. By the turn of the century, it was the hub of the ophthalmic industry in the United States as well as the world’s largest manufacturer of optical products.

Along with prescription eyeglasses, it developed new optical products for the U.S. government during both world wars, including gun sights, aviation goggles, and precision optics for the military.

Until this point, eyeglasses had been sold exclusively as a medical aid. However, that was about to change.

In New York, a young heiress and artist named Altina Schinasi had put her mind to redesigning eyeglass frames for women to be beautiful objet d’art that would add to, rather than detract from, their allure. After studying painting in Paris, she worked as a Fifth Avenue window designer, building pieces for Salvador Dali when he was commissioned to create two windows for the luxury department store Bonwit Teller. Subsequently, she took classes with German artist George Grosz, a former member of the Berlin Dada and New Objectivity groups, after he left Germany to establish himself in New York in 1933.

With these avant-garde and art world references as her starting point, Schinasi began cutting harlequin masks into the whimsical shapes she imagined. It was her breakthrough moment.

The original “harlequin” concept became the cat’s eye frame and, in 1939, she was awarded the Lord & Taylor Annual American Design Award for transforming eyeglasses into a fashion accessory that redefined glamor and revolutionized the industry.

A creative powerhouse, Schinasi worked as an artist and inventor for the rest of her life, regularly filing new patents over the course of her career.

Unexpectedly fertile in many ways, the war years were also the catalyst for the birth of Ray-Ban — one of the most enduring and instantly recognizable American brands. Originally designed as aviation sunglasses with glare-reducing lenses for pilots, they became a commercial product in the 1940s.

Newspaper images printed during World War II of Gen. Douglas MacArthur wearing the Aviator style as he landed on a beach in the Philippines were widely distributed, further etching the brand into the public consciousness.

The perennially popular Wayfarer style was born in the 1950s, and the Olympian, created in the 1960s, was worn by Peter Fonda in the decade’s most iconic film, Easy Rider.

A new age

As the United States moved on from the war, a new class of celebrity was emerging, epitomized by First Lady Jackie Kennedy and “King of Cool” Steve McQueen. With the dawn of the age of mass media — made possible in part by the new accessibility of photographic equipment and materials like those Eastman Kodak manufactured — public images of politicians, fashion icons, and movie stars became the new currency of pop culture.

These movements aligned when sunglasses became the accessory of choice for the rich and famous living in the glare of the media spotlight. They simultaneously guarded privacy and signaled status, becoming an intrinsic part of these larger-than-life personas, and a shorthand for celebrity.

From the very beginning, Eastman was tightly interwoven with this boom in ophthalmic design and new products. Tenite was adopted almost immediately for use in eyeglass frames, and prized for its strength, flexibility, and durability.

new age

The material’s chemical resistance also made it perfect for products that spend their lifespan in contact with human skin, perspiration, cosmetic products, and sunscreen. It’s also warm to the touch, making the experience of using it feel organic and tactile, and has a beautiful, high-gloss finish in a range of colors and patterns.

The process for making eyeglass frames from cellulose acetate is nearly a century old and remains closer in nature to a craft that uses industrial methods than a straightforward method of mass production, says Jiyu Chen, market development manager at Eastman.

“From an aesthetic perspective, cellulose acetate is an amazing material to work with. Our customers create patterns like the original tortoiseshell eyeglass frames using a manual process where acetate goes through multiple steps and is formed into compressed sheets. The components are machined out of the sheets and assembled by hand before being sold by brands like Gucci, Ray-Ban, Persol or Dolce & Gabbana,” Chen says. Each step requires high temperatures and extensive processing. Cellulosic acetate is the only material that can undergo these processing steps and come out not only intact but produce a beautiful pair of glasses. “The use of real tortoiseshell was banned in 1973,” says Wagner. “But between 1930 and 1970, Eastman produced polymer that could look like tortoiseshell. When cheap plastics like nylon came along, Tenite maintained that upper-echelon position because of its functionality and aesthetics.”

Into the future

For the first time in decades, the ophthalmic industry is discovering new materials to enable product innovation. Previously, eyeglass designers simply accepted available materials as the status quo, along with the cost and performance challenges that stemmed from them.

Enter Eastman’s material innovations. Eastman Trēva™ engineering biopolymer and Eastman Tritan™ copolyester are next-generation polymers that offer new options for injection molding, an alternative to traditional dryblock and wetblock manufacturing processes. Trēva and Tritan offer many aesthetic advantages over polycarbonate and nylon, the materials most often used by the industry for injection-molded eyeglasses.

Trēva is based on a cellulosic acetate propionate technology that provides significantly improved dimensional stability and allows the material to flow easily and smoothly when heated, enabling manufacturers to meet the demand for thinner, lighter, more delicate frames.

into the future

Tritan is both crystal clear and tough, providing exceptional dimensional stability with the warm feel the industry associates with cellulosics. Its durability makes it perfect for sports sunglasses and for children’s eyewear.

Both can trace their inception back to George Eastman and his first major product development. “We have developed approximately 200,000 different formulations, colors, and patterns over the last 80 years,” said Burt Capel, vice president and general manager of Specialty Plastics at Eastman. “However, we are fundamentally using the same process as when we first began compounding Tenite™ cellulosic polymers.”

What will the next 80 years look like for material innovation in ophthalmics? Eastman isn’t making any promises, but based on its history, the future is bound to be bright.