Re: Halide lamps and heat (SMTP Id#: 2935) - Reply

Jon Singer (
Mon, 31 Jan 94 19:40:49 PST

As near as I recall, the halide lamps (very different from
tungsten-halogen lamps) contain things like Scandium Chloride, a bit
of this, a bit of that, some Xenon, and so on. I think there's a
little Sodium in them too; but there can't be too much, else the color
wouldn't be what it is. The contents are balanced to give a spectrum
rather like that of daylight. Since the different metals behave
differently (reactions with electrodes, deposition on the inside wall
of the lamp, etc.), the spectrum changes over time.

I get only a few seconds "warmup before ignition", but then there's a
period of several minutes while the lamp warms up enough to vaporize
all the stuff inside and reach full brightness. They're pretty gray,
as I recall, when they first turn on, which kinda seems like Xenon to
me. (I could be 'way off base, though.)