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RLOD#48 (2020.09.05) 1993 Philips SDW-TF 100W In 1993 Philips released an inside-frosted version of its SDW-T 50W and 100W white sodium lamps in Europe, the latter of which is shown here. The tubular bulb was made diffuse via a treatment with hydrofluoric acid which roughens the inner glass surface. This process results in a good diffusion of light, which reduces glare and makes the projected light beam wider for a more ambient kind of lighting, while limiting optical losses to 3 % only. The rest of the lamp structure is identical to that of the standard SDW-T of that time, with a sodium burner operating at 95 kPa for the production of a nice warm-white light at 2500 K. Because of low expected order volumes Philips produced the SDW-TF on demand only. This particular model never became really popular in Europe and it was eventually delisted there in 1997, which makes it a rare variant of the highly successful SDW lamp platform. Keywords: Lamps

RLOD#48 (2020.09.05) 1993 Philips SDW-TF 100W


In 1993 Philips released an inside-frosted version of its SDW-T 50W and 100W white sodium lamps in Europe, the latter of which is shown here. The tubular bulb was made diffuse via a treatment with hydrofluoric acid which roughens the inner glass surface. This process results in a good diffusion of light, which reduces glare and makes the projected light beam wider for a more ambient kind of lighting, while limiting optical losses to 3 % only. The rest of the lamp structure is identical to that of the standard SDW-T of that time, with a sodium burner operating at 95 kPa for the production of a nice warm-white light at 2500 K. Because of low expected order volumes Philips produced the SDW-TF on demand only. This particular model never became really popular in Europe and it was eventually delisted there in 1997, which makes it a rare variant of the highly successful SDW lamp platform.
2020-09-05_Philips_SDW-TF_100W.jpg 2020-08-29_Christie_CXL-45.jpg GE-MML-55W-_7906.jpg 2020-08-25_Ushio_NSHA465CT.jpg AU_Post-tops_a.jpg
Lamp/Fixture Information
Manufacturer:Philips
Model Reference:SDW-TF 100W
Lamp
Lamp Type:White sodium
Filament/Radiator Type:Thermal discharge in xenon, mercury and sodium vapors
Base:PG12
Shape/Finish:Tubular etched
Burning Position:Universal
Electrical
Wattage:100 W
Voltage:98 V
Current:1.31 A
Optical
Lumen Output:4650 lm (initial)
Lumen Efficacy:46.5 lm/W (initial)
Colour Temperature:2550 K
Colour Rendering Index:83 Ra8
Physical/Production
Dimensions:149L x 32Ø mm
Factory Location:Turnhout, Belgium
Fabrication Date:May 1993
Application/Use:General retail lighting
File information
Filename:2020-09-05_Philips_SDW-TF_100W.jpg
Album name:Max / Random lamp of the day
Keywords:Lamps
Filesize:283 KiB
Date added:23 Sep 2026
Dimensions:800 x 1200 pixels
Displayed:85 times
URL:https://trad-lighting.net/gallery/displayimage.php?pid=1416
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Comment 1 to 4 of 4
Page: 1

Drew   [Wed 23 Sep 2026 at 23:48]
Very very interesting, I assume this HF etch is the original frosting technique for bulbs. Didn't know it was better for optical transmission. Very nice lamp, I first thought it was one of those frosted Iwasaki MHs.
Max   [Thu 24 Sep 2026 at 07:12]
It's the Pipkin process introduced in the mid-1920s that I am referring to here. I'm not sure what you mean by "better for optical transmission" (better than what exactly?), because it surely does introduce optical losses compared to the standard clear bulb finish. In any cases, it's certainly one of the most optically-efficient diffuse finishes there is (if that's what you meant).

Interesting that you are mentioning Iwasaki (they made inside-frosted white sodium lamps too btw), because the main reason why Philips produced a diffuse variant of some of their compact HID lamps is to cater to the Japanese market, where this lamp type is/was more popular than in Europe.
Drew   [Thu 24 Sep 2026 at 13:25]
Yes that is what I am referring to, a comparison with other diffusing techniques. Of course it's more lossy than a clear bulb, but I'd say 3% is pretty good.

I must say I am a fan of diffused tubular lamps, I wish they caught on more outside of Japan.
Max   [Thu 24 Sep 2026 at 21:06]
Same here. I like this particular finish in HID lamps... perhaps because this was a rare variant here in Europe.

Comment 1 to 4 of 4
Page: 1