The times I've tried not clamping, I've been sorry. It doesn't take much to hold them down, and back against the front if you're using the combination top/front top, but it's a real pain after the glue has dried to find the gaps where the top or front has crept away from the key. Bummer. Longevity is at least thirty years that I know of. The glue doesn't degrade noticeably over time, so I'd expect the keytops to still be there and firmly attached when our grandchildren's grandchildren go to a museum and see what a piano used to look like. While they're there, they can marvel at the beautiful tone, the soundboard that's still perfect after all these years, and how like a violin it is. Ron N
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