Some of the drop in pitch in this piano may be because the piano was bought new, if indeed it was, and some will be due to the drying out the wood due to low relative humidity. The problem at this end of the scale is because wood and metal - and carbon in the case of this piano - shrink at different rates. Regular servicing and tuning - 4 times a year for a new piano or one with new strings and twice a year for a stabilised piano - will ensure that the piano is able to settle and stabilise in a correct and accurately tuned state. Left unattended for a few years it could be that the piano stabilises in such a way that concert pitch would not be reattainable, because a significant change in tension of over 200 strings could too much for the wood.
Personally, I think 35% relative humidity is within a perfectly acceptable range and 30% would be nearing the limit I would want to see. I trust David keeps the piano away from radiators and direct sunlight. The British, mild and slightly damp climate should be fine, just worth keeping an eye on. From my experience with guitars which are also a combination of wood and strings but much thinner wood, the rate of change of temperature and relative humidity is more damaging that a specific temperature or humidity level (within acceptable limits).
The piano wasn't
quite new but still had plastic film in places, suggesting it had hardly been played since manufacture.
The tuner who came to tune it after we bought it (from Jaques Samuel, the original dealer) said he didn't think the piano would need retuning for a year!!! It was tuned on 21 October so it's 3 months, which would fit with '4 times a year for a new piano'.
The autumn/winter here have been initially HOT and dryish then pretty cold and crisp. The indoor humidity unsurprisingly really dropped in the cold, crisp spell. It has been misty/foggy for the last few days; we'll see how that transpires [sic].
Indoor temperature here is around 21C by day and 18C at night.
David's piano reference sources suggest temperature is much less critical than humidity. Recommendations for optimal humidity are VERY inconsistent, with one site suggesting 45-70% and most sounding alarm bells below 40%.
I suspect something in the old hygrometer has dried out, if that's possible; It was responding to changes but consistently
far below the new meter.
David seemed unable to get the old meter to read over 55% but I got it to 85% last night after wrapping it in a newly washed T-shirt clasped on my knee. I've put the old meter under the canopy outside now, where it's reading 67% and -1.6C. I'd like to see how it behaves in a prolonged downpour.
The hygrometer calibration kit has not yet made its epic journey from West Hampstead...
