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Author Topic: Osram (GEC) Swan commemorative lamp - help  (Read 5563 times)

Offline Siliconous Skumins

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Osram (GEC) Swan commemorative lamp - help
« on: March 21, 2009, 03:11:31 pm »
I have an unusual lamp that I have been unable to find information about or possible value.  The lamp is boxed in clear plastic, with a small black card box section in the base which holds the lamp it's self, by the cap. The box is marked on three sides, one side reveals the lamp is an "Osram (GEC) Limited 240V 100w Extralite - coiled coil", the front is marked  "Osram Centenary 1879 - 1979 Special Commemorative Lamp".  The final side mentions how manufacturing improvements allow only one filament support, and some dates when three / two supports were used.  (I'm not so sure a single filament support was a good idea - the filament looks quite saggy...)
The bulb it's self (clear GLS) is marked on the tip with " Swan Centenary Commemorative Lamp" in a circle around the normal product details stamp. The cap is a BC fitting.

As I understand it, the bulbs were only given to GEC management or presented to others, they were not on general public sale or given to the GEC production floor staff.

This bulb was one of only 15 or so that were handed out to department heads / management at the GEC Osram factory in Gateshead, UK. This was in 1979 (obviously).


I have looked and search hard all over the internet and asked a few collectors for any info, but as the Bulb is basically a 1979 era GEC production bulb that has been restamped and reboxed, I have not been able to find anything more about this lamp - nor any idea of it's possible value / rarity. The bulb is never going to be sold, it's a bit different and adds a little "something" to my small collection of other GEC bulbs produced around the same time (clearance from when the factory was closed in the early 1980's).  ;)

Hope someone can shed some light on whether  this lamp is uber rare, or common as mud, and if it's worth anything to collectors .  :)


SS

Offline Tim

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Re: Osram (GEC) Swan commemorative lamp - help
« Reply #1 on: March 23, 2009, 05:42:32 pm »
I can't help with this since I've never heard of such a commemorative before but I would be interested in seeing photos.  Do you think you could post some pictures here?


Offline James

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Re: Osram (GEC) Swan commemorative lamp - help
« Reply #2 on: April 19, 2009, 06:53:48 am »
These lamps are indeed pretty rare, I also have one but the only others I have seen are at the Science Museum in London and with ex-GEC staff.  Incidentally they were manufactured at the Wembley factory in North London, but it is understandable that some would have made their way to your lampworks in Team Valley as well.

During the later 1970s many tests were done with 40W, 60W and 100W GLS lamps having only a single support wire.  All the evidence pointed to the fact that it would be perfectly feasible to make the changeover, and thereby realise a small material saving.  Since 1979 marked the Swan Centenary celebrations, it seemed appropriate to manufacture some of these lamps and give them away as promotional items.  I understand that about 100pcs were given to attendees of the annual dinner of the Chartered Institute of Building Service Engineers (which incorporated the lighting engineering profession) that year.  No doubt several others were distributed internally within Osram.

Rather ironically the batch of tungsten wire used in these centenary lamps (which did indeed come from the Lamp Metals factory in Gateshead) showed a slightly different crystalline structure than standard production.  This was not the intention, but its consequence was that the filament sagged more than usual.  In standard production lamps made with two support wires this batch of filaments showed no difference, but for the special run of lamps made with a single support wire it did result in too much sag!  I have seen other lamps made prior to this run and with tungsten wire from a different batch and with those, the degree of sag is much less severe.

As a consequence of the Centenary Lamp run, it became clear that before the GEC could implement the switch to a single support wire, it would have to invest in better process controls both at the tungsten wire factory in Team Valley and during lamp production.  Such investment would likely have outweighed the small saving in material cost by eliminating one support wire.  The change was therefore never made, and in conclusion these few remaining lamps with single support wire are indeed very rare!

Incidentally, did you work at Team Valley factory?  When it closed some of the archive materials were transferred to Wembley.  When Wembley then closed some years later in 1991, I managed to acquire some of these materials, which includes a nice book of factory photographs dating to the opening of the Team Valley works.  I would be happy to scan these if they would be of interest to you.