mistuned unisons

Charlie Jordan wrote,

>Accordion to Richard Morse <http://accordion.simplenet.com/wetdry.html>,
the
>wet or musette tuning favored in France and Italy requires free reeds in
>unison to be tuned 20 cents apart.

Reading the page further, I note that typically there are three banks of
reeds, all tuned differently, so unisons of 40 or even 50 cents are implied
by certain accordion settings. 50 cents is definitely what I'd call an
"expressive unison" (to borrow a phrase someone else here used in regard to
50-cent intervals in Wychnegradsky's music).