Hi all!
I work in television and have done both TV and theatrical lighting, so I
thought I'd throw in my two cents worth. The envelope on these bulbs is
very thin -- they're made that way deliberately so that the filament
doesn't need to waste energy heating up the glass. The idea is that the
light will be brighter and the heat created by the burning of the filament
will just transfer through the glass and be dissapated by the surrounding
air. Even a 40w halogen gets quite hot as anyone who's burned their fingers
on a halogen desk lamp can tell you (yes, I did - experience is a great
teacher). The key point here is that the enevelope must disapate heat at
pretty much the same rate.
If there are any foreign substances on the envelope, that dissapation rate
is changed. For example, skin oil will make the glass conduct heat more
efficiently. This will cause the envelope to get a bit soft, and begine to
bulge at that point. Then as the glass cools, that spot becomes brittle.
Eventually, this spot will open up and release the vacuum inside the
envelope and the bulb will fail.
Whenever you're handling halogen or quartz lamps, use cotton gloves to
avoid leaving deposits of skin oil behind. This will help to ensure that
your bulbs will not fail prematurely.
cheers
-ch
'98 CC, Intense Blue, V6, all kinds of goodies . . .
>Next time, try putting the bulbs in without touching them with your bare
>fingers, i.e.- put a cloth around the bulb while installing it, so that you
>don't touch the glass.
>
>I'm not sure if it will make a difference, but I know that on some expensive
>light bulbs, they say to never touch the glass. If you leave fingerprints
>on the glass, they can become etched into the glass, weaken it and cause
>premature burn-out. Can't hurt to try using a cloth.......
>
>'92 Dak CC 2wd 318 3.55
>'84 GoldWing Interstate
>
>
>In a message dated 99-05-09 23:11:53 EDT, you write:
>
><< I replaced my normal 9004 bulbs with 85watt lows100watt highs bulbs about
>2
>years ago; they only lasted about 3 months. I did love output and improved
>visability of them. About 7-8 months ago I replaced my normal 9004's once
>again to the 65lows/100 highs only to once again have them bust. Any idea
>why
>this is ocurring?? What is a good brand of these higher output bulbs?? Who
>sells them? >>
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