Brass Firefighters

[beantheboy12 he/him]

I'm not entirely sure how brass feruchemy works. Does it store internal heat, or external heat? If a brass ferring were to walk into a raging fire, could they simply store all the heat that the fire provides and avoid burning themselves?

[Weltall]

Tapping F-Brass would not grant you resistance to fire since feruchemy only protects you against the effect itself (and that within limits, see Steelrunning and air resistance) but if you were to make yourself colder by storing heat you might be able to gain some temporary resistance. However, there are limits to how low you can go when you store so I don't think you could completely overcome really intense heat that way.

[SwordNimiForPresident the sword/that sword]

If you're actively storing, the temperature of your skin shouldn't be able to get high enough to burn.

[Weltall]

I think that's where the lower boundary issue comes into play. Brandon says for example that you can only store as much weight as you have to give and that for things like speed you can't even store all of that, there's some limit below which you just can't go, and you can't pull stuff out of your body at the kind of accelerated rate that you can withdraw it. I think it's possible to store enough heat to lower your temperature to the point where you'd quickly die of hypothermia without an external source keeping you alive, but there's still limits to how fast your heat gets stored and if you're in the middle of a really intense heat source like a fire, your temperature is still going to rise faster than you can store and to a level that's dangerous if you're in there for long enough.

For example, let's say you're storing twenty degrees (celsius scale) worth of core temperature, which is just a bit shy of the lowest known temperature anyone has survived and comfortably past the point when death by hypothermia can happen. Now you walk into a burning house, where the temperature is five hundred degrees or so above your pre-storing core temperature. You're getting hit constantly by a wave of heat that's far in excess of the twenty degrees you're storing so you're going to start heating up pretty quickly no matter what you do as long as you remain in that environment.

[HSuperLee]

I agree that you'd run into issues where you cannot store fast enough to not burn. However! And this is interesting. I participated in some research over the past two years that measured the vital signs of firefighters over the course of a year, and during fires, there was a tendency for their core temperatures to go well over 100° F. Theoretically, if in a modern Mistborn era you had brass ferrings in bunker gear, they could store the massive raise in core temperature firefighters normally experience and thus massively reduce the strain on their heart that a firefighter normally feels.

[Kingsdaughter613 she/her]

Then there’s those alomantic devices; you could probably alter one to store heat, and toss that into the fire. It would stop certain types of ignitions (I forget the name, but it’s when the room is superheated but lacks oxygen) and would make it easier to enter a fire. 

It shouldn’t actually stop the fire from burning though; it should remove the heat from the fire allowing it to be smothered, and preventing further consumption of fuel. (So it would go out, but not directly due to the heat removed, just indirectly.)

Hmm... fire suppression systems...

[SwordNimiForPresident the sword/that sword]

The southern Scadrians call the people that fill their brass medallions Firemothers and Firefather. I personally take this literally and assume that they stand in a fire to quickly fill medallions.

[+Invocation]

I think they'd be able to last longer in hotter environments while storing (much as @HSuperLee said), but it wouldn't be indefinite.