identify your lightbulb > bulb identification key

Squirted cellulose lamp with skirted bases

These are squirted cellulose filament lamps with skirted bases and were manufactured from 1894 to 1918.  Squirted cellulose filaments were manufactured by dissolving cotton in a solution to form a syrupy mixture that was then forced or “squirted” through an orifice or die straight into another solution of alcohol, which served to harden the squirted filament.  The resulting strengthened filament could then be wound on drums and cut to any desired lengths and then carbonized.  (The length of split bamboo filaments, on the other hand, could be no longer than the distance between the joints of the bamboo cane.)  With their lower specific resistance, these filaments had to be very long in order to give off much light.  The final configuration may be one single very long hairpin filament (see first lamp above), two hairpin filaments connected in series (second lamp), or one filament having a loop, which was either anchored to the stem or spiraled (third lamp).  All of these filament configurations could be mounted inside either a pear shaped bulb or a straight-sided bulb.  The skirted base, introduced about 1894, was used for these higher wattage bulbs (with their longer filaments) to allow the large filaments to be inserted into the bulb and also insulate the base from the excessive heat generated by the high wattages.  They were also used for lamps with multiple tungsten filaments or tantalum filaments which also took up much space.  From 1893 to 1900, squirted cellulose lamps were manufactured with plaster of paris bases.  In 1900 a few of them were manufactured with porcelain bases.  From 1901 to 1918 (when squirted cellulose was discontinued) they were manufactured with glass bases.  These lamps shown above were all manufactured in the year 1895.

NEXT PAGE in the Evolution of Incandescent Light Bulbs

  thomas edison > website navigation thomas edison > home page thomas edison > timeline : early life thomas edison > timeline : inventing the incandescent lamp thomas edison > timeline : after lighting thomas edison > timeline : legacy of invention thomas edison > classroom thomas edison > interactive modules