Fluorescent Red with Cadmium Borate Phosphor

When GE launched the first commercial fluorescent lamps in 1938, the company did not expect them to become popular for general lighting. The early white colours were about 2-3 times as efficient as incandescent lamps, but it was not known how customers would react to the tubular shape, different light distribution, colour rendering quality, along with the relatively high price, the need for complex electrical control gear and entirely new luminaires.

The fluorescent colours however were considerably more efficient than filtered incandescent lamps. As such it was considered that the primary application of fluorescent lamps would be in architectural and decorative applications, alongside the 'Lumiline' linear incandescent lamps that the company had pioneered in 1934. As such the fluorescent lamp was launched not only in white and daylight, but five additional colours of blue, green, gold, red and pink.

Blue light was produced with calcium tungstate phosphor, green with zinc silicate, and pink with cadmium borate. Gold was achieved with a zinc-beryllium-silicate modified to a yellower hue, combined with a pigment filter to remove shorter wavelengths. For many years the reddest fluorescing material was cadmium borate, whose emission peaks at about 615nm but is rather broad, extending into the yellow and green. To achieve a saturated colour this lamp has been first coated with a red pigment, and then with the phosphor. Its net efficacy is only about 3 lm/W - but this is still at least twice as good as a red incandescent lamp. In the 1940s cadmium borate was superseded by a redder formulation of zinc beryllium silicate, and then again by a brighter halophosphate combined with the red pigment.
Manufacturer: General Electric Co. of U.S.A.
Lamp Power: 15 Watts
Lamp Current: 0.300 Amps
Lamp Voltage: 56 Volts
Cap Type: G13 medium bi-pin Brass
Bulb Type: T-26 T-8 in eighths/inch
Bulb Finish: Red 2CdO.B2O3:Mn + dye
Electrodes: Coiled-Coil (Ba,Sr,Ca)CO3 emitter
Discharge Length: 394 mm 15.5 inches
Atmosphere: Hg | Ar
Luminous Flux: 45 lm (@ 100h)
Luminous Efficacy: 3.0 lm/W (@ 100h)
Maximum Brightness: 360 lux 160 foot-lamberts
Chromaticity Co-ordinates: CCx: 0.697 CCy: 0.303
Dominant Wavelength & Saturation: 623 nm 99%
Rated Lifetime: 1500 hours
Warm-up & Re-strike Time: 2 minutes Instant
Burning Position: Universal
Nominal Length: 457 mm 18 inches
Factory: Jackson MI / Bucyrus OH U.S.A.
Date of Manufacture: circa. 1941
Original Value:
References: 1) Fluorescent Lamps, C.L.Amick, publ. McGraw-Hill 1942, pp.16, 18
2) Fluorescent and Other Gaseous Discharge Lamps, W.E.Forsythe & E.Q.Adams, publ. Murray Hill 1948, pp.121, 187, 191, 192
3) Lamps for a Brighter America, P.W.Keating, publ McGraw-Hill 1954, pp.198-201
4) Photometric measurement of lamp