The Chemistry of Photography: A Father's Day Tribute

Scarlet tanager, photo by John Heino

My first experiences with a camera must have been when I was in Cub Scouts because I remember taking double exposure photos of my brother boxing with himself against the wall of our basement in Maple Heights. After we moved to New Jersey my father helped me set up a darkroom with chemicals and trays, a red light and an exposure lamp. I must have been in seventh grade when I went through this stage, and for a spell it was quite exciting, taking photos and doing all that darkroom magic.

I share all this because although I knew my father had been a chemist, primarily working in the development of latex paints, polymers and adhesives, I was unaware till this spring of his college term paper titled The Chemistry of Photography.

It begins, "The science of photograph is becoming increasingly essential in the modern world of today, yet relatively few people are acquainted with this history of, the chemistry of, or the uses of photographic art."

The paper then details the various discoveries related to how light interacts with certain materials to produce images. Johann Schulze was the first to record the observation that light, and not atmospheric conditions, was what caused silver chloride to darken. The chemists of the day found ways to produce an image but had not discovered a way to "fix" the image so you had something permanent. This would not occur till the 1800s.

My dad when young and in school.

It was Joseph Niepce who found a way to create a permanent image, with one drawback. The exposure time required was six to ten hours. (You can imagine the scene: "O.K., when I count to three say, 'Cheese.' Now hold it, don't move till I get back from Paris later this afternoon.")

Eventually Niepce hooked up with Jacques Daguerre who was also working on the problem of light sensitive materials. In 1939 Daguerre announced his process for making permanent images, which he called Daguerreotypes. That process involved copper sheets plated with silver that were highly polished and exposed to iodine vapors, which turned the surface a golden yellow.

This prep took five to 30 minutes, but had to be exposed immediately for five to 12 minutes. After exposure to light the plate was placed into another closed box where it was now exposed to mercury heated to 167 degrees Fahrenheit. Next it was washed with hypo and then distilled water.

You can see why this didn't catch on as all that popular with the masses.

Two years later paper negatives were developed by Williamd Fox-Talbert. Easier to process but not as sharp of detail in the images, so a step forward and step back at the same time.

In 1850 a process involving glass plates covered with milk and albumen was patented. Albumen is egg white, so you have to wonder how these guys came up with all this  stuff.

At the same time the use of collodion was suggested, and after a year of experimentation this process was perfected. It was known as the wet-collodion process, utilizing iodized or bromized collodion which forms, after the solvents have evaporated, into a thin, easily damaged film. On immersion in a silver nitrate bath, light sensitive iodide and bromide of silver are formed. The plate should be exposed while still moist and developed immediately.

Studio photography was reasonable to accomplish, but if you wanted to capture landscapes, all this gear was somewhat cumbersome. In short, there was great pressure on the chemists of the day to improve all these things.

What followed were Ferrotypes which produced negative images. In 1884 this guy named George Eastman secured a patent for a stripping film which was a temporary paper coated with soluble gelatin that was then coated with gelatin bromide emulsion. After developing and fixing, the image was stripped from the supporting paper and dried, hence the name stripping film.

As film sensitivity increased, exposure times decreased. In 1851 the average exposure time was 2160 times faster than in 1826. And by the 20th century it was 10,000 times as fast as in 1851, something akin to Moore's Law in the digital chip realm in our computer age.

The quest for speed and detail consumed many decades, but there was still the hurdle of color that was sought after. In the early 1900s the Autochrome process was invented, but it wasn't until the 1930s and Kodachrome that color photography and slides took off.

How brief the reign of film photography proved to be. Just over two decades later the first digital image was produced. It would be decades later before digital eclipsed film, and when it happened it happened quickly.

1973, Fairchild Semiconductor produces the first image-capturing chip.
1986, Kodak scientists offer up the world's first megapixel sensor.

The late Lee Newman

None of these latter developments were covered in my father's 1949 paper, nor were the anticipated. Whereas all previous advances had been linear explorations involving chemistry, the digital phenomenon was altogether outside the box. Silver halide, developers, sodium thiosulfates, fixatives, ammonia and emulsions all became a thing of the past.

His term paper concludes with one of the modern applications of photography: advertising. He then cites the Chinese proverb, "A picture is worth ten thousand word." Indeed!

My father became a career chemist. His first-born son eventually grew to pursue a career in advertising, ever in search of the best images to accompany content crafted to connect with readers.

Dad got an A on his paper, with the instructor's comment scribbled beneath it in ballpoint pen. "Very interesting paper." It's my hope that you've also found this abbreviated summary interesting as well.

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This has been a Father's Day tribute to an important man, Leon E. Newman