The deadly halogen touch!

It is valid. The oil on your skin will often cause the bulb to break when the glass gets hot.

Thanks TVP45, I always used glove to push in the bulbs but one day thought maybe they were just trying to say don't touch hot bulb so that dummies like me couldn't confuse things.

Can you or anyone say why skin oil even from finger tips would make hot glass of bulb break? I can kinda see if it was oil and water, but...

It's always been my understanding that the oil makes for uneven thermal stressing. That is, as the bulb glass warms up the areas with the fingerprints will be slightly cooler as the fingerprint oil or other contaminent evaporates. Those stresses supposedly (and I stress supposedly, for I've never actually seen it happen) cause the glass to crack. I suppose it's worse for halogen lamps since they run so much hotter.

Sounds plausible enough. Thanks.

TVP45,

You are correct, it is residual oils from your skin that will cause premature bulb failure.

However, in most instances, the bulb's envelope IS NOT GLASS.. It is actually transparent quartz, hence the common name "Quartz halogen" bulb.

In these types of bulbs, the filament is usually in very close proximity to the bulb's envelope, causing the envelope to get VERY HOT. Quartz melts at around 2,900º (F), which is about 1,000º (F) higher than glass.

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Just my $0.02...

Yes the mineralogy/gemstone distinction was understood.

Here's a link to a nifty interactive model.

interact with silicon dioxide