[quote="L_Marshall, post:2, topic:320224"]
Incense can theoretically used during any Mass. Most churches reserve it for Solemnities (Sundays, Christmas, Days of Obligation, etc.). Most of the time, incense is used sparingly for cost-effectiveness, even though it goes bad after a few months if it's not used. I personally like to see it used every Sunday.
It is forbidden for a priest to wear a zucchetto during the Mass, only a bishop can do that. Priests are allowed to wear the zucchetto outside of liturgical functions only. A priest, however, can wear the biretta during any Mass he says or attends in choir.
Is there a GRIM or Canon for this? I thought it was reserved for All Souls day only because of the style (all black). And I have been taught outside of mass is an always allowed.