How To Determine Type of Wood Finish
There are many types of wood with varied characteristics, but in most cases the wood furniture and surfaces of your home have been coated with some sort of protective finish. It's the finish on the wood which will determine the appropriate cleaning and repair techniques. Certain surface treatments and cleaning solutions will not be compatible with each other and should be avoided. Use the following guidelines to determine the type of finish used on your furniture, cabinets and floors.
Common types of finishing treatments are oil, shellac, lacquer, varnish, polyurethane, and paint. Painted surfaces are easily identified, but to help differentiate between the remaining types of finishes the following tests can be used.
Wood that has an oil finish will absorb linseed oil. If a small amount of linseed oil applied in an inconspicuous area beads, rather than absorbs, then it is probably not an oil finish and is likely shellac, lacquer, varnish or polyurethane.
Use a clean cotton swab dampened with acetone, and apply in an inconspicuous spot. If the acetone beads, it is most likely a polyurethane coated wood. If it doesn't, observe the spot over the course of a minute or two. Shellacs and varnishes will become tacky, while lacquer will dissolve completely. Finally, to differentiate between shellac and varnish, use a clean cotton swab to apply denatured alcohol. Varnish will react slowly, but shellac will dissolve right away.
Once you have discovered your furniture finish, a good general guideline is not to use wax products on oil finishes and polyurethane finishes, and not to use drying oils on non-oil finishes.
Caution: Never mix cleaning agents or chemicals, the result can be dangerous or deadly. Before cleaning, always test the agent on an inconspicuous location to determine its suitability and to make certain it does not damage the material. Wear appropriate clothing such as gloves and protective eyewear, and work in a well-ventilated area. Accidental inhalation or ingestion of cleaning agents can be hazardous and even fatal, particularly to pets and children.