After all the hard but enjoyable work of the turning and the less enjoyable but necessary work of sanding of their woodturning projects, many turners use the same finish for every piece regardless of the type of wood used or the purpose of the project. A little thought can make the difference between a good finish and a great one and a great finish will make a good project look great.
The first thing to remember is that the base of every finish is the surface of the wood. It should be turned as well as possible and sanded to perfection. Note that this will likely be to a higher grit for decorative rather than for functional kitchen pieces, but that all scratch marks should be sanded away. A coat of finish will make them stand out, not hide them.
Finishes can be broken down into opaque ones like paint and clear ones like varnish. Since most woodturning projects will have a clear finish, these are the ones we will consider. Clear finishes can be further broken down into four types; oils, lacquers, varnishes and waxes.
For turnings that will handle food, such as kitchen spatulas or bowls, oils are a natural choice. Typically, oils used for kitchen products are the natural ones such as canola, walnut, or sunflower oil. The nut oils will eventually dry to a semi hard finish while the grain oils will remain liquid but be absorbed by the wood. They are easily renewed by rubbing in a little oil from time to time. Also in this category is the synthetic mineral oil, a petroleum by product. It is regarded as safe for food use in the United States although not in most European countries. Oils are quick to use and are simply rubbed on and the excess rubbed off.
Varnishes and lacquers dry to a hard surface by chemical means. They give excellent protection from most solvents and liquids. As they come in varying degrees of glossiness they can fit the expectations of most users of decorative objects. Lacquers in particular may require special application equipment but most varnishes can be brushed or wiped on.
Waxes give the least protection of any of the common finishes. They are susceptible to water stain and wear quickly. However, for objects that are used for decorative purposes they may make the perfect finish, especially over a previously applied oil. Often they will give a good protection from fingerprints for bowls at a craft show when the bowl may be handled by several patrons.
Each piece that comes off the lathe is different and is turned with different purposes in mind. It is no surprise that a different finish may be considered for each one.