When Christian Blackshaw embarked on his year-long series of Mozart Piano Sonatas at Wigmore Hall in January 2012, the prospect of listening to the final recording was still a distant concern. When I meet the concert pianist in the run-up to the CD's release, it is clearly hanging over him like a cloud. 'I will have to listen to it soon,' he says, with obvious trepidation.

But then Blackshaw, 64, is by his own admission, an eternal perfectionist. 'Surely that's the only way to be,' he says. 'It's disrespectful to the composer if you don't work like a dog to get to the point where you feel like you can really give something to the audience.'

Like the great pianist Clifford Curzon, with whom he studied in his youth, Blackshaw is wary of what he calls 'the finality' of recording; the powerlessness to improve on his performance once it is committed to disc. Over 20 years ago he turned down the possibility of a German recording contract. Nowadays he is more philosophical. 'Last year a rather well known European conductor of a rather famous orchestra told me to think of recording as being like a snapshot of your children. It's just one moment in time,' he says.

One precious moment in time. Because for Blackshaw's devotees, the new disc – released today – is a rare document of a career that, for reasons out of Blackshaw's control, took a long time to come to full fruition. Two-and-a-half decades ago he was on the verge of international stardom. Then, in the Christmas of 1990 his wife died, leaving Blackshaw with three young daughters to bring up single-handedly. 'I couldn't afford somebody to look after them. I didn't want somebody else to look after my children. So I was having to earn money to support them,' he recalls. In the meantime, his high-flying solo career was put on hold. 'Suddenly a lot of offers were also not coming in...' he trails off. 'Listen, I'm not someone who is constantly seeking performance opportunities. I rather hoped that they would (find me) but it doesn't really work that way. I'm still so naïve at my advanced age.'

The turning point was the autumn of 2009, when Blackshaw began a highly acclaimed series of Mozart recitals at St George's Bristol. Around the same time he acquired a new agent, and the first engagement he got him was...the Berlin Philharmonic. Along with that came an invitation to perform at the International Piano Series (at which Blackshaw is preparing to perform the day after we meet), and, of course, the Mozart cycle at Wigmore.

But even as his career continues to gather pace, Blackshaw displays a modesty that sets him apart from many of his peers. On the concert platform he is reserved, eschewing grand gesture and theatricality in favour of a quiet intensity. Off the platform he is self-effacing. 'I do enjoy the challenge of walking out on to the stage,' he says, 'otherwise I wouldn't put myself through it, but the older I get the more I revere these composers, and the challenge becomes much bigger.'

Along with Beethoven, Schubert and Schumann, Mozart has long been a particular passion of Blackshaw's. 'It was a sort of penny dropping moment discovering Mozart,' he says. 'I think I'm a frustrated singer and to me the sonatas can be construed as being mini-operas. I find his whole being informed by the voice and the vocal line.' While he emphasises the importance of maintaining 'poise' in performance, he refuses to describe Mozart's music as 'restrained'. 'There have got to be elements of joie de vivre,' he says.

What drives Blackshaw is the constant struggle to illuminate hidden codes in the music he plays, and to tap into a composer's mindset – be it the 'depression and outbursts of anger' that pervade Schubert's last three sonatas, or the 'earthy sense of humanity' that he admires in Beethoven. 'You read Beethoven's letters frustrated with copyists, editors, the linen not being clean, not having any paper, any ink, where the food is coming from, and you realise that things haven't changed that much,' he says. Then comes the act of translating his interpretation in technical terms: 'I can sort of see, rather like a sculptor, how a form is going to emerge. Then I have to knock a piece almost to bits in order to put it back together again.'

When it comes to performance, however, his ultimate goal is a state of 'slow, calm release' where he can reach 'a sense of communion'. And does he, I ask, find music more conducive to communion than words? 'Yes', he says instantly, 'There's no small talk.'

The first volume of Christian Blackshaw's Mozart Piano Sonatas series is released on Wigmore Hall Live on September 2, 2013. Buy from Amazon