To keep up with the demand, Michael Voltaggio is again tweaking the hours at both his restaurant ink. and his sandwich spot ink.sack. Starting today, adherents to Voltaggio's sack can find it open from Tuesday through Saturday, opening from 11:00 into the later hour of 8:00 P.M., perfect for patient diners avoiding the lunch rush. Starting Monday, ink. will start Monday night service, opening from 6:00 to 11:00 P.M. and only closing on Sundays. Reservations still to be fought for online.