Marvin Pipkin

Marvin Pipkin, of General Electric’s National Electric Lamp Association, or NELA Park, Cleveland Ohio, inspecting Frosted and Q-Coated Lamps, 1949.

Inside frosting of light bulbs is achieved by acid etching of the interior of the light bulb. This method of frosting was conceived in 1925 by Marvin Pipkin (1889 – 1977) and replaced the older method of outside frosting.  As noted before, clear (or transparent) bulbs gave off a harsh light which was annoying and uncomfortable to many people, cast sharp shadows, and even presented a hazardous condition by making it difficult to see in the vicinity of the light bulb.  Attempts to cut down on this glare were made by many inventors with methods such as painting the bulb white and even partially or fully frosting the outside of the bulb.  Inside frosting was also attempted by many inventors before 1925.  They all met with failure however, since frosting the inside of a light bulb made it “as brittle as an egg shell.”   It took the genius of a bright chemist by the name of Marvin Pipkin (1889 – 1977) to create an inside frosted light bulb that would cut down on the glare but not break from bumping nor absorb most of the light from the glowing filament.

“The older method of outside frosting was not very popular, as it left lamps with a rough outside surface that was prone to breakage, collecting dust and giving off less light.  The newer method of inside frosting developed by Marvin Pipkin resulted in an interior surface with tiny smooth dimples that enabled the bulb to diffuse its light but also retain its strength and hence would not break as easily as the older exterior frosted bulbs did.  The newer inside frosted light bulbs also gave off less glare and a softer glow than did the clear bulbs and were easy to clean.

“Here is the full scoop on Marvin Pipkin’s development of the Inside Frosted Light Bulb during the roaring 1920s:

“In 1917, during the First World War, Mr. Pipkin, with his newly obtained degree in chemistry, went to work for the United States Army developing methods to combat gas warfare.  He worked as a United States government scientist in the facilities of General Electric’s  National Electric Lamp Company (NELA Park) in Cleveland, Ohio.  When the war ended, Marvin was hired by NELA Park as a chemical engineer.  As the story goes, in 1925 he was given the task of creating a strong, inside frosted light bulb.  This task had almost always been given to every new scientist or engineer who first came into NELA Park, by all accounts as a practical joke because no-one ever believed that an inside frosted bulb could ever be created.  And of course, none of them had ever succeeded.  But Marvin, despite the odds and to the astonishment of his fellow employees, hit upon the solution after several weeks of trial and error.

“He first started with the method used by many of the scientists before him - spraying acid inside the bulb to etch its interior.  This of course resulted in an inside frosted bulb, but one that had an interior with a very rough surface.  Under a microscope, the surface appeared as tiny but sharp, irregular crevices or pits.  But Marvin’s process could not stop there, for as a good engineering will attest to, any object, be it a glass window, a steel beam, a wooden rod, or a porcelain dish, that has a sharp fracture or cavity in it such as a crack or a notch, by nature then has a weak spot.  And this spot is the weakest link in the object’s chain of strength.  As such, the object will easily break if enough stress is applied to it, especially in the vicinity of the crack or notch.  Thus the inside frosted glass bulb, with its tiny but sharp, irregular crevices, is very weak.  And the slightest pressure or bump to the bulb will render its structure unstable and make it shatter immediately.

“The previous scientists and inventors who had earlier attempted to make an inside frosted bulb had always and erroneously concluded that a second application of acid to the inside would merely weaken the bulb even further.  But not Marvin.  Here is where the Marv’s next process of inside frosting comes in.  To re-strengthen the bulb, Marv created another acid solution, this time with a different mixture of chemicals.  The application of this new acid mixture to the interior merged the tiny sharp crevices into smooth dimples that re-strengthened the glass.

“The story continues that Marv decided used a little bit of his dry wit to demonstrate the bulb’s strength to his manager, a certain Mr. Enfield.  He went Enfield’s office holding six inside frosted light bulbs in his hands, some having been treated with just the first application of acid and the remaining bulbs with the subsequent strengthening treatment.  He then stood them all on his manager’s desk and tipped them over, one after the other, to stimulate the bumping of the bulbs, a typical handling process by many people.  The first few bulbs, again treated with just the first acid application, shattered very easily as expected, scattering broken glass on Enfield’s desk.  However, the remaining bulbs with the second, strengthening treatment, easily retained their structural integrity when tipped over and remained unbroken.  But that was not the end of Marv’s demonstration.  Marvin then took the unbroken bulbs and, in a confident but seemingly cockeyed manner, dropped them straight to the office floor.  The bulbs did not break but remained intact, bouncing several times.  Marvin had successfully created a strong, inside frosted light bulb with nearly perfect light diffusion, another milestone in the history of lighting.  And in spite of the broken glass on his manager’s desk, Marvin was not fired but instead was subsequently awarded the time-honored and prestigious Charles Coffin award for his discovery.  He continued to work at NELA for many more years and eventually created the Soft-White light bulb nearly 25 years later.”

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