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Cause of Dead: Defect Halogen Bulb or Finger Grease?


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#1 Igor Trajkovski

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Posted 07 May 2006 - 09:51 AM

Hi all.

One of my 500W floodlights bulb went dead.

I bought a replacement. Installed it. All fine.
After ca. 5min work it went dead.
Some ratling noise and there it goes...

I wander, was it a defect bulb or was it coused by finger grease?

As i remember my hands were pretty much clean.
I touched it at as much as possible at the porcelain ends while inserting.
Then i thought maybe i should really take more care and
not touch with skin, so i wiped all beautifully with a (enough clean i hope) cloth
and insert it with it.

I took some pix of the bulb:

Posted Image

Nice shot, a? :)

So what was it?


Thanks in advance.


Best Regards,
Igor Trajkovski
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#2 Laurent Andrieux

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Posted 07 May 2006 - 01:57 PM

Yes, finger grease may be a cause.

You should not touch it with your fingers at all. Well, if you do, just wipe it is not enough. You must you alcoholo to clean it. It can be glass cleaning liquid, optical liquid, whatever alcohol you want (never tried wine nor scotch whisky, actually...)

You "finger grease" contains an acid that attacks the quartz (the bulb is not glass) and weakens the bulb.

I don't mean I'm sure it's the cause of your problem, just as well the bulb was already weakened by another cause, but follow these recommandations anyway.
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#3 Hal Smith

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Posted 07 May 2006 - 02:14 PM

One of my 500W floodlights bulb went dead.

Igor Trajkovski


That's what they look like when they've been touched - any skin oil/acid is enough to kill a bulb. I read somewhere on a GE webpage that what destroys the bulb is actually some sort of catalytic reaction within the quartz glass, the dark side of the "a little goes a long way" principle. :D

I'd go Laurent one step further and only use 90% isopropyl alcohol for cleaning up a bulb that's been touched. 100% cotton Tech-Wipes are best for application and drying but using clean Bounty towels also works, take off a couple of turns of towel first to get to the known clean sheets underneath. I routinely clean any bulb that I personally haven't taken brand new out of a box.
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#4 Rupe Whiteman

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Posted 07 May 2006 - 02:28 PM

Whenever I change a bulb I never touch it with bare skin. I use my trusty selvyt!

rupe whiteman
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#5 Laurent Andrieux

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Posted 07 May 2006 - 02:29 PM

And like better to do so even when it's brand new since I saw a finger print on a new bulb I just took out from its paper box, once...
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#6 Hal Smith

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Posted 07 May 2006 - 03:20 PM

And like better to do so even when it's brand new since I saw a finger print on a new bulb I just took out from its paper box, once...

Ouch! What brand?
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#7 Laurent Andrieux

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Posted 07 May 2006 - 03:40 PM

Don't remember, sorry...
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#8 Igor Trajkovski

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Posted 07 May 2006 - 06:07 PM

So this is what the infamous bare-skin-touch-grease do?

I'll say again: I've known that grease will destroy the bulb
but that such a great care should be taken?
Avoiding bare hand taouching of it at all cost?

One other thing thou.

I remember the hardware shop keeper
taking out the bulb out of the packing just to
be sure it was 500W. Yeah, finger touching there.
But another thing that i noticed.

The fillament was long, not in straight line,
curved on 2-3 places. It looked like it touches the
wall of the glass inside. As you can see, on the pix,
those are the places of the breach.

Is it normal the fillament to touch the glass?
Or should it be straight in the middle?


Anyway, thanks for your advice.


Regards

Igor Trajkovski
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#9 Laurent Andrieux

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Posted 07 May 2006 - 06:13 PM

You see, the thing is that after you have touched it, you have a short time to clean it -maybe 24 hours - afterwards, the grease will begin to damage the quartz with no "return" possible. the worm is in the fruit and will begin to "eat" the quartz. So if the seller touched it when he sold it who knows if he had not touch it some time before ?

I think you could go back to his shop, tell him the lamp died after a few minutes, show him that on the liflet it's written not to touch it and ask him gently to give you another one...
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#10 John Pytlak RIP

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Posted 07 May 2006 - 10:02 PM

You see, the thing is that after you have touched it, you have a short time to clean it -maybe 24 hours - afterwards, the grease will begin to damage the quartz with no "return" possible. the worm is in the fruit and will begin to "eat" the quartz. So if the seller touched it when he sold it who knows if he had not touch it some time before ?

I think you could go back to his shop, tell him the lamp died after a few minutes, show him that on the liflet it's written not to touch it and ask him gently to give you another one...


AFAIK, if the fingerprint or oil is completely removed before the lamp is lit, no harm will be done. The etching or weakening of the quartz occurs once the lamp is lit and very hot.
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#11 Igor Trajkovski

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Posted 09 May 2006 - 06:56 PM

Today i went to the shop where i bought the lamp
and showed what happened after 5min.

- Could it be a defective lamp? - i asked.

- Might be. You know u should not touch it bare handed...
- I know. I wiped it before installing.

I pounted out that while he tooked it out in the first place
it looked wierd, the filament bent and touching the glass.
At the exact places is the damage.

He was kind enough, looked thru the avaliable packings,
and gave me a new but other brand bulb.
Now it looked fine to me.

Went home, did an thorough, for any case, alcohol cleaning.

I thing i removed 0.001 micron of the glass surface by rubbing,
and gained ca. 0.001 of an F-stop. Not bad, a? :)

Put the new bulb.

Nothing....

No light.

Hmmm......

Unscrewing again.
Took out and reinserted the lamp.

Power on - Light On!

Fine.

Let it shine for 10min.

All fine.




Regards

Igor Trajkovski
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#12 Laurent Andrieux

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Posted 09 May 2006 - 07:03 PM

You didn't mention the fact you saw him touch it when he checked it at the first place ?

Well, anyway, since you got a brand new one...

Enjoy it !
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#13 Igor Trajkovski

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Posted 09 May 2006 - 08:12 PM

Thanks Laurent..
:)

About his touching:
I thing it was at the ends of the bulb.
At the porcelain base, and some small part on the
glass.

Bare handed taking out of the bulb is nearly impossibe
only at the porcelain end. It evolvest at least touching
some glass, down there, where glass and porcelain meet.

That glass area is flat, no inner volume. (if i make sense with this)

Is that a critical "please don't touch me with your greassy fingers" part too?



Best

Igor Trajkovski

Edited by Igor Trajkovski, 09 May 2006 - 08:20 PM.

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#14 Dan Salzmann

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Posted 10 May 2006 - 06:58 AM

A bulb should not be touched at all with bare hands.
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#15 Laurent Andrieux

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Posted 10 May 2006 - 10:00 AM

John's post is interesting :

Do you John, mean that untill you don't mount and power the lamp, it doesn't matter how long the finger print was there, since you clean it before use ?

I thought it was like on a lens, for which it is said that after 24 hours or so, the phenomenom is not reversible anymore
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#16 John Pytlak RIP

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Posted 10 May 2006 - 10:22 AM

John's post is interesting :

Do you John, mean that untill you don't mount and power the lamp, it doesn't matter how long the finger print was there, since you clean it before use ?

I thought it was like on a lens, for which it is said that after 24 hours or so, the phenomenom is not reversible anymore


Lenses have anti-reflection coatings, which can be fragile and affected by the acids/oils in fingerprints. Quartz at room temperature is very impervious to most chemicals, so if fingerprints are cleaned off completely with pure isopropyl alchohol before the lamp is lit, there should be no lasting effect.

Now if your fingerprints had hydrofluoric acid in them, it would be a different story. ;)
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#17 Dominik Muench

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Posted 10 May 2006 - 10:35 AM

i just killed the bulb of a 5K arri frezzy this weekend, 125? replacement costs ....ouch :(
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#18 Laurent Andrieux

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Posted 10 May 2006 - 10:51 AM

Ok, John, thanks !

So let's say it is worth and a good habit to clean a bulb before mounting it !
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