By Chris Deziel Updated Mar 24, 2022
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Incandescent light bulbs aren't the most energy‑efficient option, but they pioneered electric lighting and dominated the market for most of the 20th century.
These bulbs generate light by heating a filament inside an oxygen‑free glass envelope. Although Thomas Edison is often credited with the invention, the groundwork began over 40 years earlier and continued into the early 1900s.
While Edison’s name is synonymous with the light bulb, earlier inventors laid the groundwork.
British chemist Humphry Davy first connected a battery to a filament, causing it to glow. In 1841, Frederick de Moleyns produced the first practical bulb by placing a platinum filament inside an evacuated glass tube and passing current through it. Edison and the Englishman Joseph Swan independently developed bulbs that lasted longer than a few minutes. Edison’s success stemmed from creating a true vacuum and using a superior filament.
The choice of filament material was pivotal to bulb longevity.
Edison experimented with numerous materials before settling on a carbonized bamboo strand, which he secured with carbon paste. Swan, by contrast, used carbonized paper from Bristol board, yielding only a few hours of life. Metal filaments appeared in 1902, with tantalum favored until William D. Coolidge mastered ductile tungsten in 1908. Coiled tungsten wires, still the industry standard, made bulbs brighter and longer‑lasting.
The filament would rapidly oxidize in air, so eliminating oxygen was critical. De Moleyns and Swan achieved partial vacuums, but Edison perfected a true vacuum by heating the bulb before evacuating it. Though fragile, this vacuum extended bulb life. Five years earlier, Canadians Henry Woodward and Matthew Evans patented nitrogen‑filled bulbs. In 1908, GE engineer Irving Langmuir introduced a mixture of argon and nitrogen, which equalizes vapor pressure and protects the tungsten filament. Modern bulbs are predominantly argon‑filled.
Edison’s first bulb featured a pair of prongs at the base; he later standardized the now‑familiar Edison screw. Alfred Swan added glass insulation to the screw base in 1887. Langmuir also pioneered the coiled filament, and Toshiba refined the design with a double‑coiled filament in 1921. In 1947, Marvin Pipkin coated the interior glass with powdered white silica, creating the “soft light” incandescent bulb that diffuses light for a more pleasant glow.
