Article: Polishes, cleaners, and myths; oh my!
Over the past 30-plus years we've encountered every type of finish possible on an instrument, and about every type of cleaner or polish available. Here's a little run-down on what we've learned, and while we're at it, a few myths debunked.
Cleaners: Almost anything is safe on a modern polyurethane or plastic finish. This would include any Japanese or Korean instrument, Ramirez guitars from about 1970 to 1995, and Taylor guitars from mid 1984. [Myth: "Wood has to breathe". Trees and cows breathe; guitars and pot roasts do not. One of the functions of finish is to slow down the movement of water into or out of the wood. As organic molecules slowly migrate out over many years, an instrument gets lighter and more responsive.]
Nitrocellulose lacquer, the most common instrument finish, is almost as accepting to cleaners, assuming it's in good condition. Water, Windex, paint thinner and naphtha are O.K. We bought a tub of a pink gel called "Magic" which works great for removing years worth of sweat and grime. A worn lacquer finish with checks or bare spots should be cleaned with care. Avoid using more than the absolute minimum of water.
Finishes on instruments from the '20s and earlier are either varnish or shellac. These finishes are usually very thin, and should be cleaned by us or someone familiar with vintage instrument care.
Polishes: [Myth: "You have to feed the wood". It's dead, O.K?] Polishes do two things?remove hairline scratches by abrading the surface, and apply a coat of something over the finish for added protection. They may also clean to some extent, but more often just shine up the dirt that's already there. Martin Polish was our favorite for many years, but the original manufacturer has gone out of business, and we're not wild about the new version. We used to recommend Dunlop 65 until we discovered it contains a small amount of silicone. Virtuoso Polish is well-liked but I have no firsthand experience with it. Basically, though, polishes are unnecessary.
Some Don'ts: Don't use "scratch cover" from the supermarket, or any spray furniture wax. Some contain silicone which contaminates the surface forever, making repair more difficult.