You may have to darken the shellac to mimic the patina, and my suggestion is
to smash up an old 78  (of which most were made from black shellac) ,
dissolve what you can in alcohol (?methyl hydrate), filter and then do some
experimentation on scrap wood to see if you can get a similar  and close
tone to the wood. It may take a few coats to replicate the patina.

 

Good luck

 

Eric