One thing I’ve learned as a compulsive used guitar collector is how
simple it is to place swirls in the end of a guitar, and how much work
it is to polish them out. I don’t polish my guitars very often
anymore, and when I do I use microfiber cloths that I get cheaply at
the auto supply store. I’ve learned to use a polishing emulsion to
get the swirls out of the ancient ones – straight strokes with the grain
seems to be the ticket.  ; I’ve been buying  large jars of polishing emulsion
 on eBay for ten bucks a small jar, although it’s really brilliant. To cut deeper I use
automotive stuff.

A couple of invalueable concepts.

Relative modality link

Parallel modality