An interesting read:
Another study found older, high-quality violins produce stronger combination tones.
apple.news
It's more than just chemicals- the lumber was old growth from the 'Little Ice Age' period, when trees grew much, much slower, so the growth rings were very close together. They could carve the tops much thinner and that makes them resonate more. Acoustic guitars are another good example of how thinner makes them resonate differently- older instruments from the early-1900s-1960s from companies like CF Martin tend to be very lightweight, yet extremely dynamic and sometimes, very loud. One of the people who used to travel to music stores & conventions described their guitars as 'so light they're almost at the point where they'll explode' while other brands made guitars that sounded good, but were much heavier (Gibson & Guild are too of them).
A local violinist lost a Stradivarius when someone broke into their house (it was on loan to him) and when it was recovered, it was in an unheated attic which is a terrible thing to do to something that's somewhat fragile- sudden temperature/humidity changes can cause a lot of damage, but it was unharmed because it was left in the case. The violinist played a bit for the news crew and the sound was incredible, considering the recording method and playback over TV broadcast.
