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This is General Electric’s first Photoflash lamp, model Number 20, which consisted of several sheets of thin crumbled aluminum foil.  Unlike today’s electronic flashes, the Photoflash was designed for a one time use only.  As the General Electric Monogram reported in its October 1930 issue, “A new lamp is needed for each flash.”  Inconvenient as that sounds, the Photoflash bulbs proved to be very popular with both professional and amateur photographers alike.  Introduced in 1930, the Photoflash was not invented by General Electric, but by a German inventor named Johannes Ostermeier, from whom General Electric purchased the patent rights.   The “starting” filament inside the bulb, which was filled with pure oxygen to accelerate the flashing, consists of two copper inner leads connected together at the tip and its length coated with zirconium powder that served as the primer.  At the bottom of the copper leads is a paper disk with either the word “Photoflash” or “MAZDA” and the General Electric monogram printed on it.  When an electric current was produced upon pressing the camera shutter, the primer then ignited the aluminum foil, producing a bright and brilliant flash.  The duration of the No. 20 flash was 1/50th of a second, which was synchronized with the shutter speed.  As long as the shutter speed was shorter than the length of the flash, the subject could be successfully captured on film.  Similar versions of the No. 20 were introduced later.  The Number 10 [see A112] was introduced in 1933 and was simply a smaller version of the No. 20 and was “designed especially for amateur use.”  It cost just 15 cents.  The No. 21 Photoflash Lamp and the No. 11 Photoflash lamp were both introduced in 1939.  (The No. 11 was also manufactured with aluminum wire. [see A53] The No. 21 model sold for 20 cents while the No. 11 model sold for 15 cents in that year.  The No. 21 emitted a flash at a rate at about 55,000 lumen-seconds compared with the No. 20’s slower rate of 45,000 lumen-seconds.  And a monstrous looking No. 75 was introduced even later.  For more information on photoflash bulbs, click here [see A55].  For further dating, if the bulb should have MAZDA, GE monogram, wattage and/or voltage etched on top of bulb [see A44], the bulb was manufactured from model’s year of introduction to 1945, when the MAZDA trademark was discontinued, or the year the model was discontinued.  If the bulb has the GE monogram on the top of the bulb but WITHOUT the MAZDA trademark, which was discontinued in 1945, bulb was manufactured from 1945 until the model was discontinued.

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