GE-Mazda White Bowl Indirect Light
White Bowl incandescent lamps were introduced by GE of America in the 1930s to meet the growing desire for glare-free lighting of commercial and industrial indoor spaces. The concept originated following the 1912 development of the classic R.L.M. light fixtures of Benjamin Electric Company. The name means "Reflector Lamp Manufacturers Standard", and it was one of the first scientifically designed and standardised industrial lighting fixtures optimised to work with standardised incandescent lamps. Benjamin sold its patent to GE who licensed it to many other competitors, and the RLM soon became one of the iconic American luminaires.

White bowl lamps were developed by Matthew Luckiesh to further improve the concept, especially from low-hung luminaires. They shield the filament from view to reduce glare and soften shadows, and direct a greater proportion of the lamp's output upwards towards the luminaire so as to attain improved optical control by the reflector. The concept revolutionised industrial indoor lighting by permitting a notable increase in light levels without an increase in glare.

The coating consists of a white enamel applied to the inside of the bulb. This results in the absorption of about 3% of the luminous flux from the filament, and of the remaining light about 80% is reflected upwards while the balance of 20% is transmitted downwards through the coating. Since the reflector is made of a diffuse white material, ordinary clear glass bulbs were used in preference to the more common inside frosted glass bulbs as those would not have offered any further improvement. They were produced in 150, 200 and 300W ratings and were supremely popular, until the 1960s when discharge lamps became more popular.
Manufacturer: General Electric U.S.A.
Lamp Power: 200 Watts
Lamp Voltage: 125 Volts
Lamp Current: 1.6 Amperes
Cap Type: E26s Brass + vitrite
Bulb Type: PS-95 PS-30 in eighths/inch
Bulb Finish: White Bowl Soda-lime glass
Filament Type: C-9/4s Pendant Wreath
Atmosphere: Argon-Nitrogen
Luminous Flux: 3,590 lumens
Luminous Efficacy: 17.9 lm/W
Luminous Intensity: N/A
Beam Distribution: 80% Upward 20% through bowl
Colour Temperature & CRI: CCT: 2950K CRI: Ra 100
Chromaticity Co-ordinates: CCx: 0.440 CCy: 0.405
Rated Lifetime: 750 hours
Burning Position: Universal
Overall Length: 205 mm 81/16 inches
Light Centre Length: 152 mm 6 inches
Factory: Ohio Lamp Plant, Warren U.S.A.
Date of Manufacture: 1939 December Date Code: -. 96
Original Value: US $0.32 (1948)
 
References: 1) GE Large Lamp Catalog, 1937 USA
2) GE Large Lamp Catalog, 1948 USA
3) Mazda Lamps Characteristics & Applications, C.E.Weitz, General Electric U.S.A., August 1939 p.31.
4) General Electric Lamp Bulletin, C.E.Weitz, General Electric U.S.A., May 1946 p.24.
5) Industrial Electric Lamps and Lighting, E.S.Lincoln, publ. Essential Books, 1945, p.21, pp.196-198.
6) US Patent 1,038,072, Reflector Shade, R.B.Benjamin, Benjamin Electric Co., Filed December 1911.
7) Photoelectric measurement.