I would like to buy an electric guitar with a natural finish(chapman rs1-6). The problem is that the guitar have a natural finish and I don't know how to clean/mantain this guitar. Are oil needed or I can just use water?
The Chapman "Natural Finish" guitars have a satin lacquer finish to protect the wood. It is finished in a way to show off the natural wood.
Executive Summary (TLDR):
For a satin finish guitar use a lightly damp cloth for general cleaning on the body and back of the neck, or a non-polishing guitar cleaning product for deeper cleaning. The unfinished fingerboard can be cleaned with Lemon Oil or similar product.
- BODY CLEANING
In modern construction, most guitars such as the Chapman models will have a type of finish that is resistant to weak cleaning chemicals such as dish detergent or a small amount of vinegar in water. You don't want to wash the guitar with a large amount of water though. A cloth that is slightly damp may be used to dust and lightly clean the instrument.
In some cases a guitar may have a penetrating oil finish instead of a lacquer finish, such as the Carvin guitar's Tung Oil finish. These may also be cleaned with a lightly damp rag. Deeper cleaning may be done with Lemon Oil, Murphy's Oil Soap, or a gun stock cleaner.
There are commercial "Guitar Polish" products available that usually contain a cleaning agent and a polishing compound of some sort. Some of the products are just a cleanser with no polish in it. There is some debate about using guitar polish that contains silicone, but I've never seen a problem with that type. The guitar polishes are formulated to clean and polish standard lacquered and painted guitars, and can be found in music stores and on-line.
For Satin and Matte finishes you want to use a cleaning product that is designed to clean the instrument more than polish it. Some guitar polishes are made to bring up a high gloss, and will cause splotchy areas on a matte finish.
While it is possible to use a furniture polish on the body of the guitar, furniture polish often contains solvents to remove wax build up, and wax to build up a polish, so it is probably better to use a polish designed for instruments. Some guitar manufacturers recommend automotive wax to polish their high gloss models.
Guitar fingerboards will usually be either an unfinished hard wood such as ebony, rosewood, or occasionally other dark hardwoods, or a light hardwood such as maple. The light hardwoods are usually sealed with a finish to keep them from staining and darkening from dirt and hand oils.
The unfinished fingerboards may be cleaned with an oil such as lemon oil or bore oil. Lemon oil is a type of mineral spirit, not pure oil from lemons, and is available as a furniture cleaner and polish, as well as sold for music instruments. Bore oil can be vegetable, seed, or mineral oil, and is sold for treating unfinished wooden instruments such as the Clarinet or Recorder. A little oil on a rag can be used to clean the gunk off the board and from around the frets.
Fingerboards made with light wood and sealed with a clear coat may be cleaned the same way as the guitar body, with a "Guitar Polish" or other cleaner.
For both types of fingerboards, if the frets need to be cleaned they may be buffed with 0000 steel wool. It is important to mask off the lacquered area around the frets of the coated fingerboards with tape or other covering before using the steel wool. On un-coated fingerboards, the steel wool will not damage the wood.