General Electric Daylight 100W Lamp

Incandescent lamps employing means to alter the colour temperature to bring it closer to that of natural daylight are nothing new.  In the States (and Europe I believe), GE have a range of daylight simulating incandescent lamps similar, if not identical to this one as part of a range called the "Reveal" series.  These never made their way into the UK however.  It would appear however, that GE have produced lamps of this type for the UK market, just without making it a part of a specific series of lamps.  I've never seen these for sale in general places like supermarkets or such.  This one was spotted in a Maplin Electronics store (When I was actually looking for something utterly unrelated). 

These lamps are mainly aimed at those looking to illuminate an area such as a workbench or utility room.  Popular uses are in desk lamps used by people working on craft projects, where the higher colour temperature tends to lead to reduced eyestrain.  The other common application is use in the houses of people who suffer from disorders related to the lack of daylight in the winter.

Different companies have gone about providing the colour temperature correction on this style of lamp in a number of ways.  The cheaper ones generally just going for a coloured lacquer on the outside of the bulb (which almost invariably ends up cracking or flaking off over time).  Other lamps try to provide a slightly higher colour temperature by running the filament at higher temperatures (especially in the case of halogen lamps), which does work to some extent.  However there is a limit to how hot you can run a filament, and generally, the higher the temperature, the shorter the lifetime is.  This is why incandescent photographic flood lamps tended to have lifetimes in the region of a hundred hours at most.  Osram recently (late 2004) released a series of colour corrected lamps called the Active range, this made use of an internal powder coating to increase the relative blue output of the lamp (actually it's attenuating the red/yellow output!) to create light of a more neutral colour.  I have not actually seen one of these lamps in person, but I believe that the colour correction there is relatively slight, unlike with "daylight" lamps such as this, where quite an extensive change in the colour of the produced light is created.

This lamp however provides this colour correction by actually using pale blue tinted glass (called Neodymium Glass).  The advantages of this are that the colour of the lamp will not fade as the lamp ages, and that it provides far greater consistency in the colour from lamp to lamp than any external coating can.  The downside of course is that it makes the production of the lamp somewhat more expensive, especially so as daylight colour lamps represent a relatively very small percentage of the total production volumes of incandescent lamps.

The light output from this lamp is a relatively cool white - I'd not say it's quite "daylight" white, but it's not far off.  (If you want proper 6400K daylight - fluorescent lamps are your answer).  There of course is a very, very big drawback to this type of lamp - they're horribly, horribly inefficient.  The problem is that the majority of the output from incandescent lamps is at the red end of the spectrum, decreasing in intensity as the wavelength gets shorter.  This means that filtering out significant amounts of the red output, as the blue glass of this lamp does, means that a significant amount of the total output of the lamp is filtered out.  Hence the output of this lamp being a meagre 500Lm, rather than nearer the 1000Lm mark as you would expect from a 100W lamp.

General Electric Daylight 100W Lamp - General overview of lamp

General Electric Daylight 100W Lamp - Detail of lamp cap

General Electric Daylight 100W Lamp illuminating my workstation from a distance of approximately two metres

General Electric Daylight 100W Lamp - overview of lamp while alight

General Electric Daylight 100W Lamp - Overview of lamp packaging

General Electric Daylight 100W Lamp - Displayed with a ruler to show size

General Electric Daylight 100W Lamp Output Spectra

General Electric Daylight 100W Lamp - Detail of text printed on lamp crown

Lamp added to the Virtual Display Shelf on Tuesday 21st January 2006 at 20:33.

References: None (Lamp packaging excepted).

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