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Re: Whoa!

At 6:11 PM -0500 on 1/14/98, Phil Payne wrote:

> Grease from human skin etches into quartz bulbs - the result looks a little
> like an old PF1 flashbulb after it's gone off.

Actually, not quite.
The oil and other good stuff(like waste from cells near the skin) burns,
and blackens. That section gets wicked(technical term here) hot because
it's not clear anymore.  That section usually puffs out, gets weak, breaks
and hence the bulb explodes.
It also could have been moisture in the headlight; I can picture a droplet
of water hitting the bulb and causing it to shatter, but that's highly
unlikely.

The oil/grease in human skin can't etch glass.  We'd be in big trouble if
it did.  Not many things will; hydroflouric acid will, but that also
dissolves flesh.  There are a few other things that'll etch glass too, but
they are very nasty stuff.

This problem with oil happens quite often in the theater buisness.  A
typical ellipsoid 6x9(6 inch lens, 9 inch reflector focal point[where the
main/first lens sits]) has about 600-750W packed into it; the bulb is
slightly fatter than a 9004, but has a huge ceramic base.  The
instrument(the whole thing) can reach temps of up to 300-400 degrees or
more.

Gobos, or metal cutouts for throwing light patterns, can easily hit +1000
deg.  If a show is going to be running for a while, and the lighting
designer is happy with the designs, they'll make up a glass "gobo" so that
it doesn't get trashed.

I made the mistake of having a 600W bulb out of the instrument once and
someone turn on the dimmer to see if the bulb worked.  If I hadn't looked
away quick enough, I probably would still be able to see the bulb :(

Brett

------
Brett Dikeman
brett@pdikeman.ne.mediaone.net
~)-|
Hostes alienigeni me abduxerunt.  Qui annus est?
Te audire non possum.  Musa sapientum fixa est in aure.
Ita, scio hunc 'sig file' veterem fieri.
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