I had a similar problem with my cat when I was revarnishing my stair treads.
According to Mr. Sasi, paintings covered in grimy varnish can sometimes be revived through cleaning and revarnishing alone.
If the etcher wishes to add to his work the plate is revarnished and more work added.
It's also blissfully easy to clean and to maintain - there's no reglazing, regrouting, revarnishing, patching up, or scrubbing down.
On the other hand, objects that were originally covered with a clear varnish to enhance and give a gloss to beautiful wood can be cleaned and revarnished without diminishing the maker's final aesthetic statement.