Just what it says on the tin, there.
I play brass instruments, even in cold Canadian Remembrance Day (Veterans day for you Americans) weather. So I thought that if I was a Firesoul or a compounder it'd be very convenient to keep toasty warm. Brass instruments get cold FAST when it's chilly outside, and that can numb the fingers well.
I wondered if Brandon had said anywhere just how hot a Brass ferring could get while tapping their metalminds. If, like an Iron Ferring becoming 20 times heavier for a time without crushing themselves, they can give themselves a big increase in personal temperature without burning themselves.
Brass has a melting point of around 900-940 degrees Celsius. The human body is normally in the 36 degree range. If a Ferring or compounder can make themselves 30 times hotter for long enough their metalminds would begun to melt. Long before that point, though, their metalminds would have to become hot enough to burn at least anyone other than the ferring themselves since Brass is a good thermally conductive metal.
I guess it's also all dependant on how much your temperature changes when you fill or tap the metalmind. Just two degrees Celsius is a BIG change in your body temperature without Feruchemy being involved. Any info you've got will be useful!
(Note, I haven't read the bands of mourning yet, but I do understand that brass metalminds play a role in the book. Technical knowledge like how warm people get is okay to fill me in on!)
