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For the manufacture of the optical system, we need to heat the fluorite ($\ce{CaF2}$) lenses to $\pu{140 °C}$. Is it possible:

  1. for some poisonous gas to be emitted? ($\ce{F2, HF}$ or other)
  2. for defects to appear on the glass? (scratches, chips, cracks and the like)

If yes, please supply sources describing the corresponding scenarios.

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    $\begingroup$ The melting point is over 1400C. There's no way it can evolve F2 without electrolysis. Think you'll be safe at 140C $\endgroup$ – Waylander Dec 3 '18 at 12:38
  • $\begingroup$ @Waylander Thanks, but I have concerns like operator live saliva (1 mg) which ph <7. Then there will be reaction which released HF. $\endgroup$ – Andrew Kachalin Dec 3 '18 at 12:44
  • $\begingroup$ Unless your operators drool is highly acidic (pH1 or lower) then they are not going to produce HF. $\endgroup$ – Waylander Dec 3 '18 at 13:22
  • $\begingroup$ @Waylander thanks, if you want give me answer below, and I'm ready to accept it. $\endgroup$ – Andrew Kachalin Dec 3 '18 at 14:06
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The melting point of $\ce{CaF2}$ is over $\pu{1400°C}$. There is no way $\ce{F2}$ can be generated without electrolysis of the molten $\ce{CaF2}$. $\ce{HF}$ is produced by reaction of conc sulfuric acid on $\ce{CaF2}$. Concentrated $\ce{HCl}$ does react with fluorite to some extend, but the reaction is very slow so, unless your operators drool like the monster from Alien, there is no chance of $\ce{HF}$ formation.

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    $\begingroup$ Some operators, though... $\endgroup$ – matt_black Dec 3 '18 at 17:09
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    $\begingroup$ I guess you could link an MSFS showing how safe $\ce{CaF2}$ is … $\endgroup$ – Jan Dec 5 '18 at 15:24
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    $\begingroup$ The MSDS for fluorite is here: sciencelab.com/msds.php?msdsId=9927120 The major concerns are contact with eyes and skin. $\endgroup$ – Waylander Dec 5 '18 at 15:48

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