Wing-forward Nigel Higgins sparked the recovery with a well-taken 58th minute goal, but the fact is that O'Loughlins would have coasted to the finish had not substitute Jason Lawler missed an open goal just before that.
Team coach Aidan Fogarty readily admitted that they had put themselves under unnecessary pressure nearing the end, saying that they lost their shape after Rathnure lost a player and lifted their game. "We were finding it hard to combat that and we struggled.
"Often when a team gets a run on you it's very hard to turn around. In the first 20 minutes we played the best hurling of the year and the last ten or fifteen minutes we played our worst hurling," he said.
And, he didn't dispute that they would be up against it in the final against Birr in Portlaoise in two weeks time. "They're four times All-Ireland champions, a super team."
Clearly a better and more mature team than they were in their last appearance in the championship two years ago at the same venue, O'Loughlins virtually monopolised the play in the first half.
They led 0-7 to 0-1 at the end of the first quarter and had added a further four points before Rathnure had their second point both scores coming from Paul Codd who had off target from three placed balls up to then.
What was surprising about the early exchanges was the weakness of the Rathnure challenge, reflected in a lack of spirit of the type one comes to expect from Wexford sides in general and a poor first touch.
In contrast, the Kilkenny side hurled with great skill and controlled the play at both ends of the field. Team captain Andy Comerford was influential at centre-back and Martin Comerford made excellent use of the ball that came his way.
However, his direct opponent, Michael O'Leary, still managed to make an impact in loose play and was one of the few to do so.
Paul Codd, who had been doubtful because of a leg injury, drifted in and out of the game and his most telling contribution was a well-hit penalty in injury time which had been won by Brendan O'Leary.
It reduced the margin to six points, 0-12 to 1-3, and was undoubtedly a boost to the Rathnure's challenge going to their dressing-room at half-time.
Nevertheless, while O'Leary played promisingly at left corner-forward and several other players showed improved form, there was never any real prospect of O'Loughlin's losing their grip because of they way they continued to dominate in key positions.
Brian Hogan was very consistent at full-back and man-of-the-match Nigel Skehan sparkled on the right wing, picking off some great scores from frees and general play and finishing with an impressive tally of eleven points.
Eight points separated the sides when Rathnure lost Joe Mooney after he received a second yellow card and Brian Dowling stretched it to nine before he was forced off injured.
It had the effect of putting more life in the Rathnure play and Higgins' late goal seemed no more of a consolation score until the margin was down to a surprising three points. However, time was on O'Loughlin's side and they deservedly advanced.
*Pat Ahearne made a number of obvious mistakes but still handled the game reasonably well.
Scorers for O'Loughlins: N. Skehan 0-10 (0-7 frees); M. Comerford 0-3; B. Dowling, M. Nolan and J. Comerford 0-2 each; C. Furlong 0-1.
Rathnure: P. Codd 1-4 (1-2 frees); N. Higgins 1-1; M. Byrne and B. O'Leary 0-2 each; T. Hogan and R. Codd 0-1 each.
O'LOUGHLINS: K. Cleere; B. Kelly, B. Hogan, B. Murphy; A. O'Brien, A. Comerford (capt.), S. Dowling; S. Cummins, A. Geoghegan; N. Skehan, M. Comerford, J. Comerford; M. Nolan, C. Furlong, B. Dowling.
Subs: N. Bergin for Cummins (injured, 27th minute); J. Lawler for B. Dowling (injured, 55th).
RATHNURE: J. Morrissey; A. O'Connell, S. Somers, D. Guiney; J. Mooney, M. O'Leary, R. Guiney (capt.); P. Codd, J. O'Connor; T. Hogan, M. Byrne, N. Higgins; S. O'Neill, R. Codd, B. O'Leary.
Sub: R. Flynn for O'Neill (56th minute).
Referee: P. Ahearne (Carlow).