Fact Sheet #8
Wood Finishing & Refinishing
1995 Dr. Leona K. Hawks Home Furnishings and Housing Specialist HI 28
A finish is used on wood for protection and beauty. Your choice of finishing material depends on the following: (1) the type of wood; (2) the use of the furniture; (3) the time available to do the finishing job; and (4) how you want the wood piece to look when you are through. In order to get good results in applying wood finishes here are some general guides to follow: (1) work in a room where there is good ventilation; (2) keep dust to a minimum; (3) if possible—don’t sand and finish in the same room; (4) remove all dust from the wood piece with a tack rag prior to applying the finish; (5) work when room temperature is around 70 degrees F and the humidity is low; (6) follow directions on the label; (7) finish underparts and interiors before finishing the outside; (8) put all used rags into the garbage.
Types of Clear Wood Finishes
There are two general types of clear wood finishes. They are the penetrating finishes and the surface finishes. 1. The penetrating finishes sink into the wood. These include: a. Penetrating resins or sealers such as Danish oils and penetrating seals. b. Oil finishes such as linseed oil and tung oil. 2. The surface finishes build up on the wood surface. These include: a. Varnish b. The newer synthetic finishes such as polyurethane (urethane), acrylic, and epoxy (catalytic finish). c. Lacquer d. Shellac e. Wax finish
These finishes soak into the wood to surround the fibers and fill much of the cell structure near the surface. The finish becomes part of the wood rather than a build up on the wood surface. Since the penetrating finish is in the wood instead of on it, small dents or scratches can be easily patched by rubbing the surface with the penetrating finish and steel wool. In addition, some of these finishes may come with the stain already added to it. With each additional coat of this type of finish, the wood becomes darker. Because penetrating finishes do penetrate the wood, they darken it slightly. However, this darkening effect greatly enhances the color and grain of hardwoods. It also intensifies the differences in the grain pattern. There are many penetrating finishes on the market. Trade names may or may not include the words resins, sealers, or oils. The label directions should indicate whether or not the product penetrates the wood. The two most common types of penetrating finishes are the oil finishes and the penetrating resins or sealers. Both penetrate into the wood to become part of the wood structure and both contain penetrating oils. However, the penetrating resins or sealers also contain resins. When these resins penetrate, they become extremely strong and hard, making the wood surface more resistant to damage. Oil Finishes They are among the oldest of all penetrating finishes. The oil finish leaves little or no surface build up and produces a natural soft sheen on the wood surface. Oil finishes should not be used over sealers or fillers. Oil finishes do not fill the pores of open-grain in woods. Some people, however, prefer open grain woods to remain unfilled. If you’re one of these people, then just go ahead and oil your wood after staining. To some people, oils are best used on closed pore hardwoods rather than open pore hardwoods. The old fashioned oil finishes such as linseed oil require little in the way of materials, but lots of elbow grease. For this reason, the traditional linseed soil finish has been replaced by modern oils that are easier and faster to apply. The contemporary oil finishes will produce the same deep soft luster as linseed oil. One of the oil finishes being used today is tung oil. Tung oil is also known as China wood oil. It is recognized as fast drying and hard and it resists water, acid, alkali, and mildew. Tung Oil Tung oil is the most durable of all...