[Avodah] A "Coal" of Metal

[Micha Berger]

The following is wrong, just explaining my hava amina: I would have
thought that heating metal to anneal it would be bishul. You're changing
something using heat, which sure sounds like cooking. Whereas heating it
until it glows would be havarah, as the physics isn't /that/ different
whether it is air glowing or metal glowing.

But in Friday's AhS Yomi (OC 334:1) we encounter the Rambam (Hil' Shabbos)
saying the reverse.

9:6: Someone who melts any type of mateches (which I am taking to mean
metal, and not "any type of iron") to the point that it becomes a gacheles
-- it is a toladah of mevashel.

12:1: Someone who heats metal in order to quench it in water [to
strengthen it] -- it is a toladah of mav'ir, and chayav.

The Raavad (12:1) is awake to the difference, and asks why not mevashel
like in pereq 9.

RYME defends the Rambam, but my hava amina seems to me more compelling
than the defense. And that's why I am writing in, for help.

The AhS says that heating in order to anneal it isn't mav'ir it all the
way like making a gacheles would. Therefore, it is a toladah of mav'ir.
Heating all the way is what we do for bishul, and therefore making a
gacheles is a toladah of bishul.

But aside from my thinking a gacheles is very similar to fire:

Take wood for example. Heating wood all the way is mav'ir. You may should
able to "cook" wood at temperatures between yad soleded bo and the wood's
flash point (around 572 deg F / 300 deg C).

But the same is true for most foods. Heat meat partway, it cooks. Heat
meat to something like 600 deg F / 316 deg C), and it will burn.

So again, it would seem to me that annealing metal is to making it glow as
cooking is to setting it on fire. If bishul is possible without oxidation,
a given for the Rambam (or Rashi or Tosafos), why isn't the glowing metal
"aish"?

Tir'u baTov!
-Micha

-- 
Micha Berger                 If a person does not recognize one's own worth,
http://www.aishdas.org/asp   how can he appreciate the worth of another?
Author: Widen Your Tent                - Rabbi Yaakov Yosef of Polnoye,
- https://amzn.to/2JRxnDF                author of Toldos Yaakov Yosef