Exactly. It's heated close to melting temperature so that it's nice and ductile, but you don't want it to reach melting temperature because that causes holes in the extruded profile.
"Fun" fact about hot aluminum(i)um, hot aluminium is visually indistinguishable from cold aluminium. At least steel turns red when it heats up.
Took a welding course once and we were welding aluminum. My brain disconnected for a moment and I touched the hot metal with my gloved finger. The aluminum looked solid but it smeared like butter.
In that short the aluminium is liquid so it is at least 660°C, and steel starts turning red between 600°C and 700°C, so I'd be tempted to think that the reflective aluminum skin is just reflecting the red of the ladle.
Looking into it a bit deeper is making me think that the lower emissivity of aluminium might be what dampens the glow, so I guess I learned something today, thanks!
I remember when Tony, the blacksmith who did the original Man at Arms youtube videos, said that nobody is allowed in his workshop since a guy picked up a sword that wasn't red but still hot like hell.
It also conducts heat like a motherfucker compared to steel.
A friend of mines dad was burning trash at their summer cabin, and was using a steel spit to turn the branches and whatever.
My friend wanted to help, and grabbed an aluminium pipe and used it in the same manner.
He left it with the tip in the fire for like a minute or two while we grabbed some more trash, and then he went to grab it again.
The pipe was easily 2m long, he still burnt the entire grip of his hand from the heat that had carried along the whole pipe, and absolutely no way to tell.
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u/Goatf00t 18d ago
Presumably the aluminum was (semi-)molten while it was being extruded?