Katharine Burr Blodgett, the invisible woman
We take for granted many things about daily life, what we see and what we don't see. Glass, especially windows, is usually transparent so that we can see through it, but reflective glare often makes that difficult or impossible. Non-reflective glass is coated glass with reflection control properties to reduce the reflection of light from the surface of the glass. Katharine Burr Blodgett was largely the person responsible for developing the means to coat glass in that way.
Blodgett was born on January 10, 1898 in in Schenectady, New York. Her father was killed by a burglar before she was born, though, and so she and her brother were raised by her mother. The family moved to France when she was 3, and she returned to New York for a year, traveled in Germany, and then made a final return to New York in 1912. They'd managed to travel so much because Katharine's father had been born into an old New England family with money.
As a result of traveling, she didn't begin school until she was 8, but she was reported to have started reading as early as two. Most of her schooling was in the exclusive private Rayson School in New York City, which provided a strong foundation in math and science. She started Bryn Mawr College (Philadelphia) at age 15 by winning the top matriculation scholarship for the states of New York, New Jersey, and Delaware based on test results. She was interested in math and physics and studied optics under Prof. James Barnes. Although she was studious, she also took part in several sports, the Christian Association, and the Science Club.
Just before graduating in 1917, she took a tour of the research laboratory of the General Electric company in Schenectady perhaps to see what it might hold in the way of job opportunities. GE had been created in 1892 as a merger between Thomas Edison's companies and the Thomson-Houston Electric Company. Coincidentally, Katharine's father had been a patent attorney, first for the U.S. Patent Office, and then for Thomson-Houston, and finally for GE in 1893. Katharine's tour guide was Irving Langmuir, a brilliant scientist who had joined GE in 1909 and was associate director. He encouraged her to expand her education if she wanted to apply for work at GE.
After graduating magna cum laude and second in her class at Bryb Mawr with a degree in physics, Katharine decided to get a master's degree. She moved to the University of Chicago in the fall of 1917 to study for the degree in physics. America had been in World War I since April of 1917, and her advisor William Draper Harkins had her working with another chemist Harvey Brace Lemon on the war-related issue of improving gas mask efficacy. The key for the work centered on how gases stick (adsorb) to the surface of activated charcoal (specially heated carbon with increased surface area due to the creation of pores). That work in surface chemistry later helped engineers develop better gas masks for the war as Germans developed more types of poison gas.
Katharine's main contribution to science began before she was hired at GE. When Langmuir joined GE in 1909, he was told to fix a problem with jewelled bearings in electric meters. Friction caused them to work inaccurately, but his research into oil coatings led to intense surface chemistry studies. By 1917, Langmuir had published a groundbreaking paper on the chemistry of oil films. His theory was that the films were only one molecule thick on water, and he could measure what that thickness was. See image below.
He demonstrated that when oils were applied to the surface of water, they spread out in a thin film, and by calculating how much had been added and the diameter of that film, the thickness could be calculated. The oils were called amphiphilic, which means they have an end which dissolves in water (hydrophilic) and one that does not (hydrophobic). That single-molecule-thick layer could be deposited
With multiple treatments on glass surfaces, Blodgett realized how the layers were positioned with alternating layers of the amphiphilic ends matching each other.
Katharine also noted that the same number of layers on glass seemed to produce the same color of film. She reasoned that a color gauge would help to determine the thickness that way, and so she built one herself. The most sensitive instruments at the time could measure to a few thousandths of an inch; but even 200 layers of oil film were much thinner. Her gauge gave measurements down to less than one millionth of an inch. It was later refined by GE, but the basic design has continued to be used by metallurgists looking at steel coatings, biochemists measuring swelling of blood cells, and biologists studying antibodies.
Blodgett knew calcium stearate was easily rubbed off, which made it unsuitable for permanent use, but she said it was still good enough for her experiments. A few days after her announcement, MIT labs showed a stronger method, and later Bausch & Lomb improved on her process to fix films more permanently on camera lenses. Before long, the treatment was also applied to windshields, picture frames, eyeglasses, telescopes, microscopes, computer screens, and with the advent of World War II, its use on submarine periscopes was invaluable.
By the time Katharine had made her discovery of non-reflective glass coatings, World War II needed her once again. In 1940, General Electric was called upon to fix two problems. One was that existing smoke screens would not cover a large enough area and were not dense enough. These were created by generators that would vaporize oil. Problems included the following with existing technology:
- many men were needed to maintain them on an hourly basis
- they stained clothing
- they irritated noses and throats
- they covered small areas but not the square miles desired
- they were potentially explosive
Smoke screens were not made of smoke like from a wood fire. Aerosolized particles would reflect sunlight and make viewing inside difficult. Langmuir determined that the best particle size would be one micron in diameter. With Blodgett and others, they developed the M-1, which sent the tiny particles out too fast to bump into each other and make larger ones, so the smoke screen was effective longer, more densely, and over a larger distance. Tested in June 1942, it covered 20 miles in a California valley. By November, they had been manufactured and used in North Africa to cover U.S. troops.
Another wartime project involved the icing of airplane wings. Supercooled water droplets in clouds remain liquid below freezing temperatures, but they freeze immediately when striking a solid surface (wings). That adds weight (reducing fuel usage) and drag (hindering flight maneuverability). Blodgett and Langmuir built one of the first controlled laboratory systems for producing supercooled droplets. They measured the fraction that struck, exactly where they landed, and how droplet size affected impact. The most dangerous conditions were found to be droplets 20-40 micrometers in diameter. Blodgett was one of the earliest users of a large analog computer built by GE to make these calculations, which helped engineers design deicing systems.
From the Biographical Dictionary of Women in Science: Blodgett was a quiet, unassuming person, who seldom talked about herself. She was a member of the Presbyterian church but was not politically active. With a reputation as an excellent cook, an amateur astronomer, and a competent gardener, she enjoyed quiet activities at home as well as out of doors, where she spent as much time as possible at her house at Lake George, New York.
On January 29, 2026, the Lost Women of Science Initiative published a podcast about Katharine's life. As part of the background, they contacted a great-niece of hers, Deborah Alkema in Massachusetts. She mentions a storage unit of Katharine's belongings in New Hampshire, and the interviewer went to investigate. Among the various papers, they found one lab notebook she had kept from her GE research days, something you are not supposed to do. Many other things were unpacked:
- love letters from her parents
- stock certificates
- news clippings of her father's murder
- photos and headlines of her receiving awards
- a Bible study notebook
And then they came upon letters from her psychiatrist. Twelve years after she began work at GE, she had become an in-patient for 2 months. She was hearing voices. Sometimes they were encouraging remarks like "Good job!" But they persisted beyond two months. The vast amount of clippings about her father's death may have been weighing on her, even to the point of taking part in seances to contact him. She kept written correspondence with a second psychiatrist for years. Was her affliction related to the loss of her father or to being the only woman in a male-dominated GE laboratory or not getting full recognition for her efforts or interacting with another personality within herself? The answer will never be known.
What is known is that, aside from the personal description in the Biographical Dictionary of Women in Science above, she published 30 papers and received 8 patents (6 of them all by herself). She won many awards and honorary doctorates before and after taking part in two World Wars from the lab bench.
She spoke at many gatherings to promote the role of women in science. Once, in 1939, she was introduced in good company as follows:
Women and their organizations continue to play an important part in the proceedings of the forum with several speakers of prominence on the program. These include Mrs. Franklin D. Roosevelt, who will speak at the first session, Mme Chiang Kai-shek, who will broadcast a message during the fourth session; Dr. Katharine Blodgett, discoverer of ‘invisible glass,’ who will speak at the fourth session…
Katharine never married, but she spent much time with her niece and children, entertaining them with fragments of her own research. Her niece said of her:
I have wonderful recollections of stuffed animals and chocolates and board games. She entertained us with marvelous stories about Houdini....[She] "always arrived with suitcases full of 'apparatus', with which she showed us such wonders as how to make colors by dipping glass rods into thin films of oil floating on water."
She was also known as a prankster as far back as university days and for being very witty with the English language. When challenged to make a rhyme with the word polyvinyl, she wrote this:
"That formaldehyde polyvinyl
If you eat it, you'll dine ill.
One night at a party,
When the guests all ate hearty,
By actual count it made nine ill."
. Katharine Burr Blodgett died on October 12, 1979 of cerebral thrombosis from an earlier car accident.
