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Oil shortens lifespan of halogen bulbs?

  1. Jul 16, 2010 #1


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    A brazillion years ago, I was taught not to handle the bulbs used in projectors under the rationale that the oil from your hands ends up on the bulb, causing overheating and shortening the lifespan of the bulb.

    I've generalized this to other hot bulbs such as the little 10, 20 and 50W halogens in common use.

    It occurs to me that this may not be valid.

  2. jcsd
  3. Jul 16, 2010 #2
    Yes, I've heard this too. I assume, without knowledge, that an oil film on the bulb glass absorbs and retains a great deal of heat; perhaps enough to eventually crack the bulb.
  4. Jul 17, 2010 #3


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    It's an issue if the oil creates a darker and/or less transparent spot on the lens, which could then cause more heat to be retained.
    Last edited: Jul 17, 2010
  5. Jul 17, 2010 #4
    Projection lamps are high temperature arc lamps made of quartz. Surface contaminants can initiate devitrification of the quartz lamp envelope leading to an explosive lamp failure.

    Quartz halogen lamps run cooler but can still be damaged. A typical operating temperature for an arc lamp might be 800 C.
  6. Jul 18, 2010 #5
    It is definitely valid. Halogens are used as standard in most Autos’. The auto parts stores tell you not to touch the glass, and will not replace them if you return a few hours later with a bulged out bulb.

    However if you do accidentally touch them you can wipe the glass with alcohol and dry. Other people say it is the salt that causes the problem.

    For a description see 03) Halogen Technology here:

  7. Jul 18, 2010 #6


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