If I made harpsichords in classical Italy, I would seal the "soundboard" and varnish the case in a way that made the wood most beautiful.
Fillers/sealers that are good for a violin "soundboard" might make a maple's varnish less irredescent, or there may be some other complaint.
So what is the role of the back? I know of course that it partakes of the general vibration modes along with the entire body. But could one have a little extra damping in the back to modulate what the top is doing? Perhaps it could widen resonances a bit without cutting their net strength too much. I think the major effect would be like adding a damper to the soundpost. At least that would be the first thing I would model in any FEA experiment. (But I am out of the FEA game)
So I ask all of you if any of you have simply filled and sealed the top against end-grain absorption of varnish and treated the back without the filler, or in some other way caused a little more varnish into the wood. (Thinking Classially, "make it look nicer")
So the question is, should one treat a back differently from a top, and will one perhaps mellow some of the response without cutting its strength very much?
I intend to do this with two new white violins I have. They seem identical in the woods and I believe are part of a run of violins from the same stock of wood. It will be interesting for me to try such an experiment. Archings seem the same, and likely are because I am sure they rough out shapes with a pantograph or CNC.