05/18/2026
In case you are interested.
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It was 1938 in Schenectady, New York. The first female scientist at General Electric lowered a glass slide into a metal trough. The water surface held a chemical film. She pulled the glass back up.
She looked at the surface. It still reflected the overhead lights. She recorded the failure in her notebook. She reached for another piece of glass.
Katharine Burr Blodgett had been doing this for years. When the company hired her in 1918, she was a rarity in the building. The men in the laboratory worked on heavy electrical grids and vacuum tubes for the war effort. She worked with water and stearic acid. Her tools looked like a kitchen setup.
The problem was as old as glass itself. When light hits a clear pane, roughly eight percent of it bounces back. In a multi-lens camera or a submarine periscope, the light travels through multiple sheets of glass. That light loss compounds. The image gets dark. By the time light reached the eye of a submarine commander or a camera operator, it was dim and muddy.
Her idea was mathematical. If she could coat the glass with a specific film, the reflection would cancel itself out. The light would pass straight through. If this failed, optical engineering remained stuck in the nineteenth century.
The theory was clean. The application was maddening.
The film had to be uniform. It had to be exactly a quarter of the wavelength of white light. In physical terms, that meant a thickness of four microinches.
Her early attempts were uneven. The chemical layers broke. The glass looked smeared. A drawer in the laboratory filled with ruined plates.
At the time, optical physics literature treated surface glare as a fixed property of glass. Records from the 1920s show that camera manufacturers compensated for the light loss by forcing actors to stand under intensely hot studio lamps, sometimes risking retinal damage. The industry accepted the reflection as a permanent optical tax. No corporate directive instructed the laboratory to fix the glass itself. The research was entirely self-directed.
Blodgett kept dipping the slides. She developed a rhythm.
The chemical film rested on the surface of the water. When she pushed the glass down, a layer attached. When she pulled it up, a second layer attached. Each layer was exactly one molecule thick.
She needed forty-four layers. The precision required was absolute.
Down. Up. Let it dry. That was two molecules.
Down. Up. Let it dry. Four molecules.
If her hand trembled, the film tore. If the water temperature fluctuated by a single degree, the stearic acid behaved differently. If a speck of dust landed on the water, the slide was ruined.
She did this for months. She built a gauge using colors to measure the microscopic thickness. She tracked the colors of the soap films, noting the exact spectrum shifts in a ledger.
There was a flaw in the early success. The invisible glass invention worked in the laboratory, but the coating was soft. If a technician wiped the lens with a cloth, the forty-four layers rubbed off. It was a laboratory trick, useless for the mud and rain of the real world.
She had to formulate a harder coating. She added barium. She adjusted the acidity of the water.
Layer twenty. Layer twenty-one. A shift in the temperature. A ruined slide. Start over.
In late 1938, she pulled a coated slide from the trough.
She held it up to the laboratory light. The glare was gone.
She placed the coated glass next to an uncoated piece. The coated glass looked like empty air. A meter confirmed it. The glass was transmitting ninety-nine percent of the light.
She had spent two decades in the same laboratory. Her supervisor won the Nobel Prize in Chemistry in 1932. He stood on stages in Europe. She stayed in New York, dipping glass plates. She missed the public recognition that went to the men working on high-voltage projects upstairs.
The world accepted the reflection as a law of physics, so she measured it until it disappeared.
The military classified the technology immediately. By 1942, American submarine commanders were looking through her coated periscopes in the Pacific. The lenses did not reflect sunlight. The enemy could not see the glare on the surface of the water.
Hollywood used it next. The camera operators for a new film called Gone with the Wind used her coated lenses to capture colors that previous cameras lost. The rich reds and deep shadows on the screen were a direct result of the trough in Schenectady.
The patent was filed. Production scaled. The process was automated. The company made millions.
Today, the coating is standard. It sits on the camera lens in your pocket. It coats the windshields of passenger vehicles. It is on the eyeglasses you use to read a screen.
You look through her work every day. You never see it.
Katharine Burr Blodgett: the woman who made glass disappear.
Source: General Electric Archives.
Verified via: The Smithsonian Institution, National Inventors Hall of Fame.
(Some details summarized for brevity.)
