not sure whether this topic belongs here, but i couldn't think of another part of the forum where it would, so here goes nothing :
the standard thermos flask has a glass inner body with a metallic reflective coating on the outside
i was just curious what metal(s) are being used or have been used to establish this reflective layer
i've been unable to find anything on-line that goes beyond describing it as a "metallic layer" (in all cases unspecified which metal(s) are involved)
does anyone out there know ?
Very difficult to find a specific metal cited in my searches but surely it has
to be aluminium as it is so cheap and already used for so many other purposes.
The closest description I could find was "silvered".
Also the fact that simple unsilvered aluminium flasks are also made seems to show that they may well be using aluminium for the silvering.
I always assumed it was mercury and perhaps it (or some equivalent ) is used in more efficient types of vacuum flasks.
What do they use on reflective surfaces in optical surfaces, I wonder (like the Hubble mirrors ,perhaps) ?