In article ,
Adam Funk writes:

Interesting, thanks. Out of curiosity, what is the stuff they use
between the resistance wire & the casing of a water-heating element?

Magnesium oxide is the traditional material for many decades,
highly compressed as the element casing is rolled down to its
final diameter though multiple pressure rollers.

Its downside is that it is hygroscopic (likes to absorb water),
and if the outer casing is not perfectly sealed, moisture will
get in and generate earth leakage, and eventually failure (even
if the heater is not a submerged type).

It would not surprise me if some other suitable non-hygroscopic
material had been found more recently, but I haven't heard of
any such.

--
Andrew Gabriel
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