I accidentally deleted Horace's response about hammer weight not being the only factor to consider, so I can't quote it, but that's the gist, and I agree. I think one valuable feature of measuring hammer weight is when we are deducing the maker's intent about the leverage/keyweight/inertia system, rather than tone. Whether we agree with the maker or not, at least we know what was intended. When we are looking for the maker's intent on tone, Horace's distaste for reductionism certainly comes into play, but we have to fumble along with the best tools we have, which include: 1. Yes, the mass (or our best guess of what it used to be), because it also speaks to the maker's intent about tone 2. The size and material of the molding (& coving, tapering, etc. -- the apparent ratio of molding mass to the mass of the hammer) 3. The type of felt used -- how "layer-y" it is, etc. 4. How the felt feels when thumbnailed, bent over to the side w/the thumb, etc. 5. How much stiffener was apparently used 6. The harmonic spectrum of the hammer and how it responds to needles, and for that matter what the needles feel like going in. We can't know for sure how resilient the original felt was, but we can deduce it to some extent by the spectrum. 7. Historical knowledge of the maker's style 8. Probably other things For instance, a light, heavily pressed and steamed hammer made from a thin, short-staple felt on thick birch moldings will not sound the same as light, bouncy felt, lacquered, and on light, thin mahogany moldings, even if they weigh the same. If you can voice them out to sound similar, it's hard work at best. Since we can't copy the originals to a gnat's eyebrow, at least we have a leg up on what general style of hammers to use, as well as what tradeoffs we will have to make either to obtain a tone more or less like the original, or a different tone which is at least consistent with what the piano was designed to produce. Bob Davis
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