Incandescent - Tungsten Filament

Updated
14-VII-2018
Although the tungsten filament lamp offered a higher efficacy than its tantalum predecessor from the outset, it was not able to immediately replace the former filament material. This was owing to the very brittle nature of the original tungsten filaments - which were made from powdered tungsten particles sintered together to produce a fine wire. The difficult manufacturing process led to high costs and filament breakages in service were commonplace.

The problem was not overcome until the 1910 development of drawn-tungsten wire, this ductile material being much more robust and eminently more suitable for lampmaking. From this point onwards, practically all of the former filament materials were abandoned.

A third development in tungsten lamps was the important change from vacuum to gas-filled designs, and the parallel change from straight wire to coiled filaments. This gave a further significant boost in lamp efficacy combined with a reduction in costs. Lamps of all three tungsten technologies are featured on this page.

Squirted & Sintered Tungsten Filament

Auer

50CP

Osram lamp with sintered metal filament
~1908-10

Graetzin

16CP

Sintered Metal Filament
~1908-10

Henrion

16CP

"Osmine" Sintered Metal Filament
~1909-10

Osram-GEC

17W

German Auer lamp made for British GEC
1910

GE

40W

First American Tungsten Filament
1909
   

Drawn Tungsten Filament

GEC

40W

Osram Drawn Tungsten "Angle" Type
1911

S.F. Auer

30CP

O.R. Omnidirectional Radiation Spiral Filament
~1910-15
   

Coiled Tungsten Filament

GE-Edison

500W

Mazda 'C' Early Style 500W Gasfilled
1915

Philips

100W

Tungsten Gasfilled HalfWatt
1919

GEC

100W

Swan Centenary GLS with Single Support Wire
1979

GEC

100W

Experimental GLS with Plastic Cap
c.1980
       

Infrared Recylcing Coating

Duro-Test

65W

Tungsten Gasfilled with IRC Coating
c. 1980