You can’t apply the same kind of bow pressure with gut strings so it’s more about bow speed
I've just been playing the Brahms Double Concerto on a gut-strung instrument with Thomas Zehetmair and the Orchestre Révolutionnaire et Romantique under John Eliot Gardiner. This was a new experience for me – I had played on gut strings before but never a concerto with orchestra. My preparation didn’t involve exercises so much as getting used to a new set-up – how the instrument responded and how to treat it. I kept two weeks clear before the first rehearsal to experiment with it.
I used my regular cello – an Antonio Cassini from c.1675 – restrung with handmade strings. Gut strings are much thicker than steel strings and also there is much less tension, so you don’t need to press down as hard on them – it almost feels like playing harmonics; I had to work out how gently I could press on the strings for the note still to speak. Shifting also took some getting used to because the surface of pure gut strings is much rougher than strings wound in metal or silver.
I had to rethink and practise my vibrato, too. Gut strings are richer in natural overtones, and the shaping of the note is determined more by the way you use the bow. If you’re used to using a lot of vibrato, it takes time and guts to trust that the colouring of the note is interesting enough. Gardiner is not a fan of vibrato in general, especially automatic vibrato, so we tried to be very specific about using it.
You can’t apply the same kind of bow pressure with gut strings so it’s more about bow speed. Before the first rehearsal I met up with Steven Isserlis, who famously plays gut strings, to ask him for advice. I learnt a lot from observing his bowing technique and his bow hold, which is very relaxed and is ideal for gut strings. His bow reminded me of a paint brush rather than the ‘sharp pencil’ you might apply to steel strings.
I used a shorter Tourte bow from 1810 for the concerts. We tried to stick to Brahms’s original bowings and that’s quite a challenge in some places, especially for a gut-strung cello because the thick, lower strings need a lot of bow. If you end up with eight or sixteen notes, imitating the violin part, it can be borderline impossible. Fortunately, Gardiner’s tempos were quicker than I have experienced with other conductors, so it was a very fluid Brahms.
Photo: Marco Borggreve