Why the Old Chair Survived
A chair you can lift with one finger is usually a chair you will replace within five years. Weight is not the whole story, but it is a decent first signal about the joints underneath.
Joints, not surfaces
What fails first is almost never the seat. It is the point where the leg meets the frame, and a joint that is glued and pegged rather than stapled is the difference between a decade and a season.
Sit in it for ten minutes
Comfort in the showroom means nothing. The chairs that last are the ones still tolerable after a long meal, and you cannot learn that in thirty seconds.
Old ones have already proved it
A chair that has survived forty years has passed a test no new one has taken. Reupholstering is less costly than replacing, and the frame is the part worth paying for.
A chair you can lift with one hand rarely lasts a decade.
More notes to follow.