To fill holes and cracks in woodwork, furniture or cabinets, there are several different patching compounds that the home mechanic can utilize. For a long-lasting, neat-looking job, it is important that the correct type of putty be used and that it should be properly handled and applied.
Wood putty (also known as wood plastic or wood filler) must not be confused with the paste wood fillers which are typically used for filling pores in open-grained woods before finishing. These paste fillers are put on by brush over the entire surface of the board, and they're not designed to fill nail holes,cracks or openings in badly fitted joints. For patching jobs of this kind, a wood putty or wood plastic should be used.
Choose ready-mixed putty or a powdered type which should be mixed with water before use. The ready-mixed putty could be either a quick-drying plastic compound or a linseed oil putty of the type generally used for sealing windowglass inside the sash frame.
The quick-drying plastic compounds usually comprise of an adhesive mixed with wood powder. They dry quite rapidly and are ready for use when the can (or tube) is opened. Because of their rapid drying characteristics, together with the relatively coarse texture of some brands, this makes them hard to finish up smoothly—especially in shallow depressions.
As these wood plastics dry to a dense finish, they don't take stain easily. So, when patching wood that will be finished using stain, it is best to stain the wood first. Then fill up the cracks or holes with wood plastic in a color matching the final finish. A lot of companies produce a line of factory-colored patching materials for this purpose alone, or you could tint your own by putting in powdered pigments or universal tinting colors to the natural-colored putty.