Brendan Rogers and Chrissy McKaigue traded scores with Niall Fitzsimmons in the early minutes as both sides battled for supremacy.
Coleman and Shea Cassidy continued to exchange frees as both sides went score for score before the Down champions broke into an early lead.
Niall Milligan burst through the Slaughtneil defence before slipping the ball to Daithi Sands who fired to the net on 21 minutes to give Portaferry a 1-7 to 0-8 lead.
Coleman hit his club’s last score of the half from the next play before Slaughtneil rattled off four scores in a row before the break.
Shane McGuigan, Cassidy (free), Ruairi O Mianain and Cormac O’Doherty were all on target to give the holders a 0-12 to 1-8 lead at the break.
The expert marksmanship from Coleman and Cassidy from placed balls continued to be the story of the second half with little between the sides.
McGuigan added another to stretch the lead out to four points before substitute Bradley claimed possession among scrum of bodies to fire to the net, as the Derry champions led 1-18 to 1-14 with seven minutes left on the clock.
McGuigan and O Mianian tagged on further scores as Coleman tried to bring his side back into the game from placed balls.
Paul McCormack’s side were getting a huge boost from their experienced bench and it was another sub, Jerome McGuigan who rounded out the day with a huge score to seal his side’s spot in the Ulster decider in a fortnight’s time.
“We have to manage the next couple of weeks and assess the men for injuries, but it’s great to have the game and winning it is what we came to do, so now we have another game to look forward to,” McCormack added.
“St John’s of Antrim, a club with a rich history in hurling and football like Slaughtneil, so we will have a look at what went well for us today, have a look at St John’s, but two weeks’ time will be another battle.
“Did we do everything right today? No, we didn’t, but we were good in patches and did enough to win.”
BBC News