Hesalite Crystal -- Why?

[andrema]

I did a little digging prior to buying my Speedmaster and I found this interesting -- from the Omega site.

Question - Why is the Speedmaster Professional "Moon Watch" fitted with a hesalite crystal?

Answer - The Speedmaster Professional is worn by astronauts in outer space. When NASA chose this watch, they requested a hesalite crystal, which "unlike a sapphire crystal" does not break into tiny fragments on impact.This feature is very important for astronauts, as the tiny fragments of a broken sapphire crystal would pose a danger in a zero-gravity environment.


Hesalite crystal facts -- from http://omega.watchprosite.com/show-forumpost/fi-677/pi-3285826/ti-537576/s-0/


Hesalite or from other supplier could also be brandname Perspex. Both of them a PMMA sheet


[b]Tradename Material Manufacturer

Hesalite PMMA sheet G-S Plastic Optics gsoptics.com][url=http://gsoptics.com/]gsoptics.com

Perspex PMMA sheet Lucite International [url=http://www.luciteinternational.com/]www.luciteinternational.com]www.luciteinternational.com][url=http://www.luciteinternational.com/]www.luciteinternational.com



Proporties of the materiel is:

• Exceptional light transmission with virtually no colour bias - even in thick blocks.
• Excellent resistance to outdoor weathering.
• Good resistance to impact.
• A high gloss, hard surface.
• High tensile strength and rigidity.
• Easily thermoformable with simple workshop tools.
• Easy to clean.
• Capable of being fully recycled.