8mm Forum: Bulbs - New Old Stock

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Topic: Bulbs - New Old Stock

Thomas Dafnides
Expert Film Handler

Posts: 247
From: St. Louis, Missouri USA
Registered: Dec 2009

posted September 13, 2013 09:29 PM

I bought some "new old stock" CXL bulbs (Osram) off of Ebay. They are very old, judging from the price tags on the boxes ($6.95) ..my guess is from the 60's.
Looking at the interior of the bulbs they have a yellow tinge to them...I am inclined to believe that they have hours of usage....(they do light with a slight warm cast).....opinions? A quality brand bulb unused, manufactured 30 years ago...will it have the same lumination life span as the newly manufactured item?

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted September 13, 2013 09:38 PM

What usually makes a lamp die is the tungsten in the filament slowly boils off and deposits on the inside of the glass envelope and when the filament becomes too thin it becomes fragile and breaks.

This deposition turns the glass gray and evenually black, not yellow.

If the bulbs really are zero or low hours, the filaments should still be full thickness and should run the full rated hours.

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All I ask is a wide screen and a projector to light her by...

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Maurice Leakey
Film God

Posts: 5895
From: Bristol. United Kingdom
Registered: Oct 2007

posted September 14, 2013 02:19 AM

Is this the "Mae West" lamp?

Old stock lamps sometimes have a problem with the seal between the glass and the metal holder, thus allowing loss of the vacuum, but in this case they would often expire the moment power was applied.

Your "new" lamps sound a bit suspect. I suggest you take up the matter with the eBay seller with the possible claim for a refund.

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Maurice

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted September 14, 2013 06:44 AM

Agreed,

If there is oxygen inside there the tungsten will basically burn up as soon as it gets hot.

This would be very quick, so if you get much past a couple of minutes you are probably OK.

I wonder if maybe the yellow tint is an oxidation of a coating on the outside of the envelope.

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All I ask is a wide screen and a projector to light her by...

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