Sunbeam Mazda Sintered Tungsten, 1909

This lamp is representative of one of the Tungsten filament models, made in 1909 by General Electric. GE operated a near monopoly of the American lamp business until 1905, when its carbon lamps with an efficacy of 3.4 lumens per Watt, and metallised carbons of 4.25 lm/W were threatened by the invention of the 6 lm/W Tantalum lamp by Siemens of Berlin. In 1906 GE secured rights to the tantalum lamp for a very high price, and thereafter redoubled its efforts to take a leading role in the development of future lamps.

Once again the key developments were taking place in Europe, and in 1906 GE sent two of its leading engineers, John Howell and Willis Whitney to Austria, Hungary and Germany to secure American rights with all four of the tungsten researchers - a huge $1.5 million deal. Alexander Just & Franz Hanaman, a pair of lab assistants at Vienna's Technische Höchschule were recognised as achieving the first practical lamp, and their design is employed here.

Finely powdered tungsten was mixed into a gum arabic and sugar solution, and squirted through diamond dies at high pressure to yield a fine wire. The wires were cut and bent into U-shaped hairpins before being sintered to remove binders and yield pure metal. The filaments are very fragile and have been fixed to the support wires by arc welding instead of the usual clamping technique. Lamp efficacy almost doubled to 7.85 lm/W, and incidentally the reason for the frosted bulb is to diffuse the glare of the brilliant tungsten filament. Its high cost made it unable to supersede tantalum immediately, and production continued until 1910 when it was abruptly made obsolete by Coolidge's much stronger and cheaper drawn tungsten wires.
Manufacturer: Sunbeam Division of National Mazda (GE)
Lamp Power: 103 Watts
Lamp Voltage: 106-108-110 Volts
Lamp Current: 0.940 Amperes
Cap Type: E26s Brass + vitrite
Bulb Type: S-95 S-30 in eighths/inch
Bulb Finish: Clear Soda-lime glass
Filament Type: 5S-2 Squirrel Cage
Atmosphere: Vacuum Red P getter
Luminous Flux: 950 lumens
Luminous Efficacy: 9.5 lm/W
Beam Intensity: N/A
Beam Distribution: N/A
Colour Temperature & CRI: CCT: 2475K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.477 CCy: 0.412
Rated Lifetime: Approx. 1000h
Burning Position: Universal
Overall Length: 200 mm 77/8 inches
Light Centre Length:
Factory: Ohio Lamp Plant, Warren U.S.A.
Date of Manufacture: May 1910 Date Code: 29X
Original Value:
References: 1) Lamps for a Brighter America, P. Keating, McGraw-Hill, 1954.
2) A Century of Light, J.A. Cox, The Benjamin Co. Inc, 1979
3) The Electric Incandescent Lamp, E.J. Covington, NELA Press, 1998.