This is a Victorian dresser that came in to be restored, luckily it had it’s original shellac finish so it could be repaired and not refinished. One of the advantages of shellac and lacquer is that they can be re-amalgamated.
Next what remained of the finish was re-amalgamated with denatured alcohol. Basically the old shellac is dissolved with the alcohol and a brush and then brushed out to cover the surface. You are covering the entire top with what finish is left. On a piece with less severe damage this can be done without the need for further repair.
The top polished.