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GE-Mazda White Bowl Incandescent

GE-Mazda White Bowl Incandescent

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This is an early white bowl incandescent lamp made by GE-Mazda of America. It has a white enamel coating 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.

It seems they were developed for use in the iconic so-called RLM Fixtures found in early industrial lighting (the first fixture that was standardised by the Reflector Lamp Manufacturers Institute of USA, to promote good industrial lighting). Although the RLM institute was only founded in 1919 the fixture itself dates back to its 1911 invention by the Benjamin Electric Company. It was the first scientifically designed reflector to work with standardised incandescent lamps to achieve the highest glare-free light output for industrial lighting. The white bowl lamps were especially popular in low-hung medium-wattage RLM fixtures because they completely shield the filament from view, allowing a notable increase in lighting levels without increasing glare. As such they were only made in ratings of 150, 200 and 300W.

Does anyone know when these white bowl lamps were first introduced? They are present in mid to late 1930s catalogues but not earlier, which seems strange because frosted bowl incandescent lamps were introduced in the carbon filament days around 1905, and the RLM type reflectors were becoming popular from about 1912 onwards. Perhaps the concept was only revived following Silvray's 1933 invention of the silver bowl lamps and associated fixtures, which have a similar effect but of course with no light transmission through the bulb crown.

IN WC D GE 105-200PS30DAY-E26.jpg IN R GE 120-100A21SB-E26.jpg IN R GE 125-200PS30WB-E26.jpg 1C9CBF3E-2CF4-4E54-8323-0A9E0AFE7A59.jpeg

Light Information

Light Information

Manufacturer:GE-Mazda
Model Reference:200PS30WB
Lamp
Lamp Type:Incandescent
Filament/Radiator Type:C-9
Base:E26s/25
Shape/Finish:PS-30
Service Life:750h
Electrical
Wattage:200 W
Voltage:125 V
Optical
Lumen Output:3590 lm
Lumen Efficacy:17.9 lm/W
Color Temperature:2950 K
Color Rendering Index:100
Physical/Production
Dimensions:205 mm
Factory Location:Ohio Lamp Plant, Warren OH, http://www.lamptech.co.uk/Documents/Factory%20-%20US%20-%20Ohio.htm
Fabrication Date:December 1939
Application/Use:RLM Fixtures

File information

File information

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Filename:IN R GE 125-200PS30WB-E26.jpg
Album name:James / Incandescent
Keywords:Lamps
File Size:187 KB
Date added:Oct 13, 2018
Dimensions:1199 x 1598 pixels
Displayed:99 times
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merc
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Oct 14, 2018 at 11:11 AM Author: merc
Interesting design. Thanks for sharing and for the story!

Not a misoLEDist...

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Oct 14, 2018 at 02:35 PM Author: Cal
That’s a sweet lamp.
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