As Black Sabbath's Bill Ward will readily attest, it's usually musical, personal or contractual differences that prevent a band from getting back together again for one last hurrah. For US punk hero Bob Mould, it's the pressures of mid-term papers and seminars that have conspired to stop Sugar from reuniting.

Mould, who is about to celebrate the 20th anniversary of Sugar's Copper Blue with a series of re-mastered editions of the trio's back catalogue and playing the album in its entirety with his current band, exclusively tells The Quietus that a reunion is off the cards thanks to the academic commitments of former bassist David Barbe and drummer Malcolm Travis.

Asked if he'd approached his former bandmates about playing Copper Blue with him, Mould says: "They were the first two people that I approached. And the years change all of us and both David and Malcolm work at universities now."

He continues: "We got together and had a great talk but ultimately – especially David but also Malcolm – we couldn’t make the schedules work. David’s a full-time teacher now and I can’t expect him to drop everything he’s doing to play a bunch of rock shows. So that’s where I started but David in particular said, 'I really can’t do this but I think it’s totally great that you’re doing it and I 100% endorse what you’re doing'. Life puts us all in different places."

Mould went on to pour scorn on Dave Grohl's alleged attempts to re-unite Mould with his erstwhile cohorts from Hüsker Dü.

"Dave’s the sweetest guy in the world and very kind with his words towards Hüsker Dü and we’ve gotten to be great friends over the last couple of years but I’m more likely to join Foo Fighters!" he laughs.

"Sometimes it’s hard to go back. Sometimes the experiences we share with musicians are very much of that time and people change," he says.

Taking a philosophical approach, Mould says, "If Hüsker Dü hadn’t have ended then I wouldn’t have recorded Copper Blue. I think there’s a reason why you don’t go back. The one thing I would say to everybody is [that if a re-union did take place] then it wouldn’t be the thing that you thought it was and maybe you’d be better off watching the Camden Palace DVD!"

Sugar's re-mastered and expanded albums Copper Blue, Beaster and File Under Easy Listening are out on May 28 on Edsel Records. A full interview with Bob Mould about the making of Copper Blue will run on the Quietus next week.