On Michelle Henning’s “A Dirty History of Photography” and the invisible foundations of photographic beauty.
Photography is regarded as the art of the visible. It shows what stood before the camera, captures a moment and preserves it for a future in which both that moment and, usually, the people depicted will have long since disappeared. Yet photography is remarkably reliable at keeping its own creation out of the picture. In a landscape photograph we may see a river, but not the silver that entered other rivers through the manufacture and processing of photographic materials. We see the light on a face, but not the coal whose combustion powered the chemical industry that made film light-sensitive in the first place. And we admire London’s famous fog without smelling it, feeling the scratch in our throats or noticing the soot its residents later blew out of their noses. The image appears pure because it never shows us its bill.
Michelle Henning, Professor of Photography and Media at the University of Liverpool, examines precisely that bill in her book A Dirty History of Photography: Chemistry, Fog, and Empire. This is not another history of photography in which Daguerre, Talbot, Kodak, Leica and a procession of canonised masters make their familiar appearances. Henning shifts attention from cameras, inventors and photographers to the medium’s material infrastructure: silver, gelatin, coal, coal-tar dyes, factories, wastewater, trade routes, colonial ownership and military interests. Photography emerges as an industrial product with an enormous metabolism, rather than a disembodied means of producing images. It had to take in raw materials, consume energy and excrete waste. The fact that the latter is not generally pasted into the family album makes it no less real.
This touches my own work more directly than it might initially seem. I photograph digitally, yet try to give my images the appearance of historical gelatin silver prints: deep blacks, hard light, visible grain, a surface allowed to look as though it came from a darkroom even though it has never seen one. Engaging with Henning’s ideas adds another layer to that aesthetic choice. I quote the beauty of a material whose industrial history was anything but beautiful. This does not mean I now have to view that aesthetic with a guilty conscience. Guilt is rarely a useful design tool. But it changes how we look when we understand that the historical gelatin silver look was never merely a question of style. Behind its beauty stood mining, coal, animal bodies, chemical factories and wastewater.
Henning’s book is divided into 36 short chapters—as many exposures as a roll of 35mm film typically contained. Instead of following a straightforward chronology, it traces connections between Ilford’s factories, London’s fog, colonial trade routes and military research. Drawing on Mary Shelley’s Frankenstein, Henning describes chemical photography as a kind of creature: the material has a body, responds to its surroundings and leads a life of its own that its makers cannot fully control.
Gelatin emulsions are made from animal material. They absorb moisture, swell, melt and age. Dust, grease, temperature and chemical compounds leave traces. What the laboratory rejected as a fault, fogging or contamination, Henning reads as an involuntary account of the world in which the material existed. A damaged emulsion then reveals more than a faulty image: something happened beyond the intended subject to which it, too, was sensitive.
Here lies one of the strongest ideas: a photographic layer is not sensitive only to light. It has other sensitivities that the industry had to suppress as far as possible. Emulsions could react to sulphur dioxide in the air, impurities in water, oils from human hands and invisible radiation. The history of photographic technology is therefore also a history of controlled perception. Sensitivity was engineered, restricted and marketed. Film was supposed to register red, yellow or infrared radiation, but preferably not the filth from the factory next door.
Henning illustrates this through Ilford’s Britannia Works. The factory stood opposite a gasworks. According to her research, air contamination destroyed around 25,000 sensitised photographic plates in the drying rooms in 1899. Ilford responded with an early system for conditioning and purifying the indoor air. Inside the factory, sensitive emulsions were protected from the polluted atmosphere, while outside, coal-powered industry continued to contribute to precisely that atmosphere. A clean enclave was created for the product without fundamentally questioning the dirty surroundings. The clean room ended at the factory wall.
Henning’s discussion of London’s fog is particularly striking. What appears mysterious and almost poetic in historical photographs was no kindly meteorological blanket laid over the metropolis. The smog consisted of moisture, soot, sulphur compounds and industrial emissions. It irritated the airways and could be fatal. Photographs turned it into a visual signature of the imperial capital: outlines dissolved, shafts of light pierced the dense air, street lamps became luminous islands. Photography documented pollution while transforming it into atmosphere.
The fog in the picture does not stink. It does not sting the eyes or deposit soot in the viewer’s lungs. Poison becomes mood; industrial violence becomes a picturesque veil. We see the lost romance of a great city, while the people who lived there would probably have been quite happy to trade a little romance for a little more breathable air. The camera need not even lie. It merely has to show us the part of the truth that can be translated into light.
At the same time, that atmosphere attacked the photographic material. Sulphur compounds could cause fogging, stains, blisters and cracks. Fog was thus both subject and co-author: it lay before the camera and penetrated studios, darkrooms and emulsions. The photographs depicted polluted air and carried its chemical traces on their surfaces.
Does an image change once we know the conditions under which it was made? The aesthetic quality of a historical photograph of fog does not automatically diminish when we learn of its toxicity. Our judgement may nevertheless change. This concerns me too: in the studio, I use fog to make light visible. Visually, I can create a related mood. But a similar effect in the image certainly does not mean a similar reality before the camera. That very distinction can easily disappear behind the beauty.
This is by no means confined to photography. Behind marble stands a quarry; behind bronze, ore extraction and smelting. Cathedrals and palaces did not arise from divine inspiration alone either. Photography, however, was particularly good at concealing its industrial origins because it was long understood as a direct trace of reality. As though nature herself had picked up a pencil and happened to forget to mention the chemical factory.
The subtitle Chemistry, Fog, and Empire makes clear that Henning goes beyond environmental history. She calls photography a “daughter of coal”. Coal did more than supply energy for factories, railways and steamships. By-products of coal processing yielded coal-tar dyes that became crucial to the development of photographic sensitisers. Early emulsions responded primarily to blue light. Only certain dyes extended their sensitivity to other parts of the spectrum, making orthochromatic and eventually panchromatic materials possible.
The black-and-white image, often regarded as an especially truthful or almost natural representation of the world, thus rests on an artificially shaped perception. Film saw what its emulsion and sensitisers allowed it to see. What we call photographic naturalness is the successful outcome of a long sequence of artificial interventions.
For Henning, the colonial connection is not merely a matter of the subjects depicted. Photography certainly served to survey, classify and represent colonised territories and peoples. Yet its material production already depended on global trade routes, resource extraction and transport systems closely bound to European empires. Coal-powered ships carried minerals, animal products, chemicals and finished photographic materials through a network of imperially controlled ports. Ilford sold its products as far afield as the West African coast.
At the same time, European photographers judged other climate zones according to the technical and cultural standards of their own medium. Heat and humidity were considered photographically problematic, while the British sky was treated as a more or less natural starting point—even though that very sky was so enriched with industrial fumes that it occasionally killed the people living beneath it. The familiar climate was declared the norm; the foreign one, the problem. This, too, reflects an imperial order of seeing.
Another connection leads to the military. During the First World War, aerial reconnaissance drove the development of sensitive plates and films. State-funded research promoted infrared-sensitive materials and panchromatic emulsions; the seizure of German patents and formulas gave British manufacturers access to previously secret sensitisers. Modern photographic perception also took shape in military laboratories. To this day, cameras can make people visible and thereby vulnerable to attack. The photographer’s peaceful eye has armed relatives.
The “dirty history” becomes most tangible with silver. Silver halides form the light-sensitive basis of traditional photographic materials. During manufacture and processing, silver compounds could enter rivers through wastewater. Used fixer was a particular carrier of this pollution: it dissolved the silver halides remaining in the emulsion after development, making the image stable in light. What freed the photograph from the darkroom left chemical residues elsewhere.
Henning therefore plays on the ambiguity of fix: to make permanent, to arrange or manipulate; a fix is also an awkward predicament. The image was allowed to leave the darkroom. So was its chemical residue.
Henning points to photographic silver in the sediments of the Thames and its toxicity to certain aquatic organisms. Precision matters here: the Thames being described as “biologically dead” in 1957 cannot be attributed solely or predominantly to photography. Municipal sewage, oxygen depletion and numerous industrial discharges acted together. Nor does digital photography explain the river’s subsequent recovery; environmental legislation, sewage treatment plants and remediation were decisive. Photographic production formed part of this wider system of pollution. Its residues did not disappear merely because we stopped noticing them.
The book therefore makes poor ammunition for the tiresome holy war between analogue and digital photography. Anyone who concludes from it that digital cameras are ecologically clean is taking the same easy way out as the analogue romantic who considers film an artisanal natural product because he turns off the lights to develop it. Digital photography requires mining, semiconductor manufacturing, batteries and global supply chains. Add to these the equipment and infrastructure for storage and transmission.
An analogue negative can sit in a box for decades. A digital image can be stored on multiple devices and servers, copied and transmitted again and again. The much-invoked cloud is no ethereal heaven in which memories float among friendly little fleecy clouds. It consists of buildings, cables, cooling, metals, energy and labour. Without a concrete assessment, this produces no outright winner in an environmental comparison. What is clear is that the digital image, too, has material prerequisites that are invisible within it.
When I give my digital photographs the appearance of old gelatin silver prints, I quote grain, emulsion and darkroom, while the image data arise from a sensor, software and electrical energy. The past remains present as an aesthetic while the conditions of production change. Which materials a later print actually adds is another decision. The historical look alone tells us nothing about that.
Henning’s reflections take nothing away from the beauty of analogue photography. They merely take away its innocence. Art does not become poorer when we understand its prerequisites; it becomes more complicated, and complication is usually more interesting than nostalgia. Behind the silver lies mining, behind the fog lies coal, and beneath the riverbed lies the sludge in which history has settled.
The pure image probably never existed. It was simply exceptionally good at keeping its dirt outside the frame.
About the Book and the Sources Used
This discussion is not based on a complete reading of the book, but on Henning’s published essays, lectures and conversations, together with reviews and information from the publisher. It engages with the ideas gathered from these sources; it is not a book review in the strict sense.
Michelle Henning: A Dirty History of Photography: Chemistry, Fog, and Empire. University of Chicago Press, 2025/2026, 320 pages, 11 colour plates and 62 black-and-white illustrations.
Publisher’s page and table of contents – University of Chicago Press
Michelle Henning: “Photography’s Other Sensitivities” – Media Theory
In-depth conversation with Michelle Henning – Pittsburgh Review of Books