Guitarists’ expectations regarding finish on their guitars have long been guided by the oldest widely used guitar finish of all, French polish.  French polish has a number of advantages for guitars—

• It can be applied in a thin build.  Thinness is a universally valued finish property among guitarists for optimal acoustic benefits.
• It will dry and cure on rosewood.  Varnish applied without a shellac sealer will never dry on rosewood; it will remain tacky forever because of the unique properties of the wood resins.
• The French polish application technique makes possible a smooth finished surface without the need of any tools other than the cheesecloth bun (called a “rubber”) used to apply it.  The technique can also fill the notoriously large pores in rosewood to near-level.

There are several serious problems with French polish—

• It’s very delicate in terms of abrasion resistance and doesn’t wear well at all.
• It is vulnerable to all sorts of chemicals, starting with water, human perspiration, alcohol, etc.
• The technique is monumentally time consuming.  French-polishing an entire guitar takes many, many hours even for luthiers who have had lots of practice.

A French polish finish can be kept in good condition with occasional restoration, but this takes professional knowhow.  Most guitarists neglect this until the French polish is worn off down to bare wood, which then gets dirty and oily, making restoration much more difficult.  Because of all its drawbacks, I no longer offer French polish as an option on any part of my guitars.  The options I do offer, however, come really close to the good points of French polish.