Quite a few manufacturing processes
involve heating the materials up real hot
, two pieces of metal are heated
until a third metal melts over, wets
, and bonds them.
, the metal to be joined is heated so hot
that it melts and flows together.
, glass is heated
until it acts like the viscous liquid
that (according to folklore
) it always was.
And when you're engaging in any of these processes,
sooner or later you're going to learn --
directly and personally --
the Glassblower's Lament
"Hot glass looks exactly the same as cold glass."
(In other words, you can't tell just by looking at it
whether a recently-worked piece is still too hot to touch,
and if you guess wrong -- Ouch!)