In article
,
"B.B." u wrote:

When my halogen bulbs burn out on my car they leave a clean shiny
metallic coating on the inside of the bulb. If you could find out what
process causes that you might be able to reproduce it to coat your jars.
Sorry i can't be more specific.

Bascially, what you're seeing in a burnt-out halogen bulb is the result
of an EXTREMELY crude and uncontrolled example of the coating method
called "sputtering". Halogen bulbs run *HOT*. Hot enough to literally
"boil off" atoms of the filament metal. The halogen gas the bulb is
filled with is supposed to (and at least to some extent, does) cause the
metal vapor to re-deposit on the filament, rather than the glass,
achieving two results: 1) Longer life (since the filament stays a
filament, rather than turning into a coating on the glass) and 2)
Brighter output, which is a direct result of the reduction of plating on
the glass to block the light. When they burn out "slowly", it's often
due to "micro-leaks" that let the halogen out, and "plain air" in, which
in turn allows the "plate onto the glass" process to start happening,
and continue until the filament is eroded so far that it's unable to
maintain physical integrity and breaks.

A "mechanical" burn out (A hard jolt, etc) won't show the plating,
because the atmosphere in the bulb has remained constant, but the motion
from the impact has broken the filament.

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