Will the ultrasonic cleaner help with the fast tarnishing of the new brass? Or does that actually require polishing to remove the tarnish?
just to make things clear,
and answer the question you asked:
new brass don't tarnish faster, it's tarnish different! ( I have both )
while old brass retain close to it's color when tarnish
new brass change color to bonze like dark brown,
you may notice that new brass tarnish is very common in sculptures
when both clean old brass is more yellowish like gold,
but, it's not gold just brass.
ultrasonic bath if done right does help with little parts and springs better then anything else,
also it make polishing much more fast/easy and affective.