Line drawings of several designs for doorknobs and keyholes fill the page of an early twentieth-century manufacturing catalogue.

Doorknobs in various styles by Sargent & Co., New York (factory in New Haven, Connecticut), 1912. Image courtesy Cornell University Library

Doorknobs and Disinfectants

If you’re like most people, you probably don’t spend much time thinking about doorknobs. Or at least you didn’t until recently, when knobs, handles, ATM keypads, and every other shared surface began to feel like an ominous platter of ripe microbes. Let’s be honest: in the last six weeks, many of us have taken Clorox wipes to door hardware that we had not bothered to wash in months (or years).

Pandemic-induced cleaning aside, when it comes to doorknobs, I am not like most people. As a curator interested in the functional designs of everyday life, I am fascinated by the combined ubiquity and invisibility of doorknobs. Take a quick count: how many doorknobs are in your residence? Or, imagine a typical day before social distancing. How many thresholds would you pass through as you navigate home, transit, school, work, coffee, lunch, errands, and social and cultural engagements? Picture the doors in your mind. Which ones have knobs, levers, push plates, or handles? What are their shapes, colors, materials, and textures? If you have trouble recalling, you are not alone. Most doors offer such seamless interactions that they fail to register in the conscious mind.

Door hardware also provides curious and instructive examples of mechanical principles. The most familiar doorknobs today (external link), lever locks, feature a rotating knob which disengages a hidden latch. The knob turns an internal spindle and cams, translating rotational motion into linear motion and sliding the latch. Imbedded springs ensure that everything returns to its original position when we let go.1 

Doorknobs can be made from almost any solid material, but metals have long been favored for their malleability and strength. As a result, those of us who study craftsmanship consider door hardware to be a branch of metalworking, albeit one closely allied with carpentry and cabinetmaking. Before the 19th century, most finishing hardware was custom work. The finished product reflected the technical and aesthetic acumen of the maker. The industrial revolution gave rise to hardware manufacturing centers in Britain, and later, New England. Brass became preferable to iron because of its resistance to corrosion. (As a copper alloy, it also happens to have natural antimicrobial properties.) It is also easily cast or stamped—methods suitable to mass production. Surviving catalogues from Connecticut’s major factories attest to the thousands of varieties of doorknobs that were produced. In the modern era, commercial doorknobs remain widely available, while artisans and designers continue to produce custom work for unique projects.

Four pages from a catalogue featuring gray-toned renderings of metal doorknobs in various styles.
Doorknobs produced in Stamford, Connecticut offered in Yale & Towne Manufacturing Company's Art Metal Work catalogue, 1897. Image courtesy Columbia University Libraries
Wrought-iron door hardware including handles, knockers, keys, and locks decorated with botanical patterns.
The Philadelphia blacksmith Samuel Yellin was one of the most talented, imaginative, and prolific American metalworkers of the 20th century. His custom door hardware graced public and private buildings across the country. Left: Door handles, George G. Booth residence, Cranbrook, Detroit, 1919, wrought iron; right: Lock, handles, and key, George Woodward residence, Krisheim, Chestnut Hill, Philadelphia, ca. 1912, wrought iron. Images courtesy Leeds Art Foundation and Samuel Yellin Metalworkers Archives

Doorknobs, like light switches or shower controls, are prime examples of human-centered design. The best versions work so well that we forget they exist, but poor designs leave us frustrated: pushing instead of pulling, stuck in the dark, or shivering in the tub. We have conceptual models for such objects—doors hinge on the right or left, and swing toward us or away—but the hardware itself must provide us with sufficient visual cues. In other words, as cognitive scientist and design guru Donald Norman explains, “Knowledge has to be both in the head and in the world.”2  To grasp Norman’s point, we need only to think of failed attempts to use doors. The round knob on my best friend’s front door is centered. Should the door drop down like a drawbridge or swing up like a DeLorean? Of course not. But, only from trial and error do I know that the hinges on are the left and that I must push hard. Most of my acquaintances’ front doors are a blur, but I always remember this one. In door design, as in disease prevention, failure is far more memorable than success.

The entrance to a brick house.
A centered door knob presents a conundrum for the would-be user. Private residence, Pittsburgh, Pennsylvania. Image courtesy Rachel Delphia

Knowledge Gap: Microbes

We have been making doors for millennia and complex hardware for many centuries, but it has taken us much longer to comprehend that microbes perched on a doorknob could make us sick. We might reconceptualize protecting ourselves from germs as a design challenge that has consistently befuddled humanity, one rooted in early misunderstandings of disease.

Germ theory, codified by scientists in the late 19th century, is the widely accepted model that pathogens enter the body and cause illness. Today, we also know that many pathogens are communicable: they can be shared from person to person (or from person to doorknob to the next person who touches said doorknob and fails to adequately wash her hands for the full duration of “Happy Birthday”). Yet, for much of human history, people believed that illnesses were caused by imbalances of the four humors in the body or by miasma, a foul-smelling vapor thought to arise from decaying matter.

A skeleton holding two bones as if they are a violin and bow walks through an interior strewn with bodies while other people flee.
Gustav Richard Steinbrecher, after Alfred Rethel; Death the Strangler, The First Outbreak of cholera at a Masked Ball in Paris, 1831, 1851, woodcut on paper; Carnegie Museum of Art, Leisser Art Fund, 90.3.2

Even those who suspected the existence of microorganisms often relegated them to smelly locations or underestimated their threat. Writing in the 1st century CE, Marcus Tarentius Varro cautioned, “there perhaps exist in marshy places, animals which are invisibly small, and which cause serious diseases by invading the body through the mouth or nose.”3  In 1634, the Dutch scientist and inventor of the microscope Anton van Leeuwenhoek documented what he called “animalcules.” He confirmed their presence in air, water, and soil—and showed that vinegar distressed them—but he stopped short of forging a link between microbes and disease. Meanwhile, most people believed that epidemics emanated from unsanitary locations, like sewers, rather than spreading through germs that could pass between individuals via air, water, or surfaces.

Despite missteps and misinformation, humankind made astute observations and deployed effective behavioral adjustments. For instance, people realized that it could be useful to keep the sick away from the healthy. Quarantines and social distancing were implemented during bouts of bubonic plague in Europe between 1400 and 1600.4  During yellow fever epidemics, Americans who were able to do so fled cities like Philadelphia for homes in the less crowded countryside. They may not have understood why their tactics worked, but they saved lives nonetheless.

The facade of a house made of white stone, with a portico supported by two columns framing the entrance.
Then as now, a house with ample surrounding land offers a luxurious buffer in times of illness. Sidney M. Stone; Exterior elevation, House for Roger Sherman Baldwin, New Haven, Connecticut, ca. 1830–1840, ink, casein, watercolor and gum arabic on card; Carnegie Museum of Art, Purchase: Gift of Henry J. and Drue Heinz Foundation, 92.49

In the late 1840s, Hungarian physician Ignaz Semmelweis made important discoveries about handwashing and disinfecting surgical tools. He observed significantly higher rates of maternal mortality among mothers attended by medical students rather than midwives and surmised that the medical students, who often moved from educational autopsies to maternal exams or deliveries, were spreading the contagion. By implementing handwashing and cleaning tools in a chlorinated lime solution, Semmelweis’s clinic lowered maternal deaths from over 18 percent to less than one percent.5 

Diffuse Disinfectants

Semmelweis’s story raises the matter of disinfectants, defined today as substances that destroy or stop the growth of germs on objects. In earlier times, the meaning elided direct reference to pathogens or surfaces. An abstract fixation on “bad air” prompted disinfection strategies via noxious fumes. In 429 BCE, Hippocrates recommended fumigating Athens during an epidemic by burning pungent herbs, and ancient Greek and Indian literature offer stories of burning sulfur to disinfect rooms.6 

People wearing robes pass by dead and dying figures in a large open area surrounded by buildings, steps, and statues from antiquity.
Michael Sweerts; Plague in an Ancient City, ca. 1650–1652, oil on canvas; Los Angeles County Museum of Art: Gift of The Ahmanson Foundation, AC1997.10.1. Image courtesy

Well into the 19th century, American newspapers promoted dubious environmental treatments using DIY formulas for evaporating liquids, sprinkling absorbent solids, or burning compounds to disinfect a space. The Galveston Daily News recommended disinfecting a sickroom by burning a shovel full of coffee grounds.7  Mary Perkins, a Virginia resident, saved a clipping that suggested suspending a cloth soaked with chloride of lead.8  Another of her cutouts prescribed the broad application of dust:

Hot weather breeds disease, and all foul places about the premises should be disinfected at once. Nothing is better than charcoal dust; throw a handful over every little place that exhales a bad odor, and especially the privy vault. Road dust is the next best convenient thing.9 

Other household records suggested the purifying power of green copperas (iron sulfate). One gentleman made a note to self: “1 lb. of green copperas [. . .] dissolved in 1 quart of water and poured down in sinks or sellers [sic] or where there is any bad smell, will effectually [sic] concentrate and destroy the foulest smells.”10  A printed clipping advised the same substance be “placed under a bed in hospitals and sick rooms, [. . . to] render the atmosphere free and pure.”11 

Recipes for disinfectants collected in a scrapbook of newspaper clippings and handwritten entries in a ledger.
Left: Assorted newspaper clippings in a scrapbook, including one entitled "A Disinfectant," ca. 1860s; right: William Walker records a recipe for a household disinfectant in his account book under the heading “Worth Knowing,” 1845–1852. Images courtesy The Winterthur Library, Joseph Downs Collection of Manuscripts and Printed Ephemera

In 1876 The London Times decried the widespread attempts to clear the atmosphere: “Aerial disinfection as commonly practiced in the sick room is either useless or positively objectionable owing to the false sense of security it is calculated to produce.” 12 

While Americans and Britons were avidly mixing chemical concoctions to burn or evaporate, few appear to have considered wiping down doorknobs for the sake of sanitation. They did not lack surface disinfectants: early examples included strong bases derived from lime (inorganic calcium compounds) or readily available acids like vinegar.13  People simply reserved these substances for more visibly filthy or odorous objects. Leading housekeeping manuals recommended hot lye for cleaning sinks or removing unpleasant smells from jars yet made no mention of doorknobs.14  One recipe for cleaning brass from a popular manual used a diluted acid: one ounce of oxalic acid mixed with one pint of soft water, followed by a buffing paste of turpentine and rottenstone (powdered limestone and silica). While this likely contributed to disinfection, the expressed intent was aesthetic: “Brass cleaned in this manner looks beautifully!”15 

Doorknobs, Meet Disinfectants

Few of our ancestors would have thought to disinfect their doorknobs or other frequently touched surfaces as we are implored to do today. The 20th and 21st centuries can proudly claim these practices, following the widespread acceptance of germs’ viability on objects and the commercial availability of household disinfectants. Bleach has been the gold standard since Clorox achieved national distribution in 1932. Yet, bombarded as we are with messages about disinfection today, it is easy to overlook that antibacterial soaps, alcohol-gel hand sanitizers, and antimicrobial wipes with quaternary ammonium compounds are millennial products. Purell hit the shelves in the late 1990s, and germ-killing wipes followed in the early 2000s. These tools are remarkably new additions to the arsenal of design solutions to combat microbes.

The present situation has everyone thinking overtime about disease-fighting solutions. The novel coronavirus is psychologically threatening because—despite everything we have learned over the last century and half—gaps in our knowledge persist. We don’t have as much information about COVID-19 as we do for more established diseases. Like all germs, it is invisible to the naked eye, providing no visual cues to guide our actions. Although most of us lack the authority to implement systemic design solutions, we can do our best to participate in social distancing and disinfect the surfaces in our homes. It may be a weak balm, but I am sticking with the small certitudes of doorknobs and disinfectants.

Two sleek aluminum door handles presented side by side.
Left: Philippe Starck, designer, Franz Schneider Brakel GMbH & Co., manufacturer; Handle, lever door, 2000, aluminum; right: Jasper Morrison, designer, Franz Schneider Brakel GMbH & Co., manufacturer; Lever, door handle, 2000, aluminum; Carnegie Museum of Art: Gifts of Franz Schneider Brakel GMbH & Co., 2001.23.3.1 & 2001.23.2.1


  1. Laurel Sheppard, “Doorknob,”, accessed March 31, 2020,
  2. Donald A. Norman, The Design of Everyday Things (New York: Basic Books, 2002), x.
  3. J. Blancou, “History of disinfection from early times until the end of the 18th century,” Rev Sci Tech 14, no. 1 (March 1995): 32.
  4. Dave Roos, “Social Distancing and Quarantine Were Used in Medieval Times to Fight the Black Death,”, accessed March 25, 2020,
  5. Imre Zoltán, “Ignaz Semmelweis: German Hungarian Physician,” Encyclopedia Britannica Online, accessed April 2, 2020,
  6. Blancou, “History of disinfection [. . .],” 32.
  7. “A Simple Disinfectant,” Galveston Daily News, April 10, 1892, 3.
  8. “A Good Disinfectant” [clipping], Mary Perkins, recipe book, ca. 1870–1890, Document 195, Joseph Downs Collection of Manuscripts and Printed Ephemera, The Winterthur Library, Wilmington, Delaware.
  9. Ibid., “Charcoal as a Disinfectant” [clipping].
  10. William Walker, account book, 1845–1852, 1892, Document 399, Joseph Downs Collection of Manuscripts and Printed Ephemera, The Winterthur Library, Wilmington, Delaware.
  11. “A Disinfectant” [clipping], household and culinary recipes, ca. 1860s, Document 1675, Joseph Downs Collection of Manuscripts and Printed Ephemera, The Winterthur Library, Wilmington, Delaware.
  12. “An Important Report on Disinfectants,” The London Times, reprinted in St. Louis Globe-Democrat, August 19, 1876, 3.
  13. Blancou, “History of disinfection [. . .],” 33–34.
  14. See “The Care of Rooms,” 367–378 and “Warming and Ventilation,” 419–432, in Catharine E. Beecher and Harriet Beecher Stowe, American woman’s home, or, Principles of domestic science: being a guide to the formation and maintenance of economical, healthful, beautiful, and Christian homes (New York: J.B. Ford and Company, 1869); Eliza Leslie, Miss Leslie’s lady’s house-book; a manual of domestic economy containing approved directions for washing, dress-making (Philadelphia: H. C. Baird, 1863).
  15. Leslie, Miss Leslie’s lady’s house-book, 218