MCI Project Summaries 2008 - Smithsonian Institution

MCI 6175 Edison’s Light Bulb
MCI Staff: R. Jeff Speakman, Judy Watson, Lynn B. Brostoff
Questions have arisen regarding the method of manufacture and composition of Edison’s
earliest light bulb filaments. Specifically, what were the filaments made of and how did the
technology change (through the addition of different additives to the filaments) during the early
years of light bulb manufacture. It is hypothesized that Edison would not have had to add
anything to Bristol board and Madake bamboo filaments because the former contains kaolin and
the latter has lots of silica; both of which would contribute to the formation of a conductive
ceramic if heated properly in the absence of oxygen and the presence of fluxes (such as any salts
in the organic material). However, it is uncertain if this is the case, or if Edison did indeed use
additives.
Two filaments viewed with MCI’s SEM
SEM image of processed and used bamboo
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