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It looks like it typically had a current passed though it to ignite zirconium threads.

What properties of rhenium made it the best metal to use for this?

  • $\begingroup$ Well, I think this is a dumb question, but what is a "flashbulb"? Are you asking about the photography flashbulb one? But, then that WP page doesn't mention "rhenium" anywhere... $\endgroup$ – Gaurang Tandon Mar 16 '18 at 7:14
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    $\begingroup$ @GaurangTandon For the youngsters out there: there was an era when photographs were taken using photographic film. For much of this era electronic means of producing bright light (xenon electronic flash devices and white LEDs) were rare. So people used chemical means of creating flashes of bright light (originally magnesium powder, later a variety of enclosed bulbs containing things like zirconium wire the could be ignited electrically or mechanically). Some of these clearly used rhenium igniters. ;-) $\endgroup$ – matt_black Mar 16 '18 at 10:49
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    $\begingroup$ Given the price of rhenium, it is quite likely the igniter is an alloy. However, Wikipedia does suggest that rhenium filaments for, e.g. mass spectrometers, are more stable then alternatives in air/oxygen atmospheres. Combined with the refractory nature, one could imagine that getting the filament really hot really fast in air (so the zirconium threads burn rapidly) is pretty stressing on the filament, and rhenium would be a good choice. $\endgroup$ – Jon Custer Mar 16 '18 at 13:06
  • $\begingroup$ A friend suggested that perhaps rhenium was chosen for its spectral output when burned. These bulbs were around at the beginning of color photography, so good color rendering index would have been desirable. I will need to test the spectrum of these compared to, say, burning iron or aluminum! $\endgroup$ – bigjosh Apr 2 '18 at 15:23
  • $\begingroup$ Rhenium is also an extremely rare and expensive metal. This type of flashbulb was single use, disposable; and professional photographers used them by the dozens. So any rhenium content would have been extremely small. Something like a plating on another element. Now, most lightbulbs are either evacuated, or filled by an inert gas. Flashbulbs are instead filled with oxygen, to get the brightest possible burn from their fuel. Now here I speculate: prolonged storage in an oxygen atmosphere would likely be corrosive, leading to failures. The rhenium may be an anticorrosion plating for reliability. $\endgroup$ – Securiger Aug 30 '18 at 12:34

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