Wood filler and wood putty are similar products that have similar uses. Because they look alike and have comparable names, people often mistake one for the other. Using the wrong product, however, can produce time-consuming consequences. For example, wood putty is oil-based; therefore, it's disastrous to use with water-based finishes. Wood filler, on the other hand, has a greater variety of formulas made from different materials, each of which is designed for a specific purpose, such as for use with unfinished woods, water-based finishes and lacquer finishes.
Wood filler is a putty-like material made from latex, clay, polyurethane, lacquer or epoxy. Some wood fillers can be mixed with sawdust and other fillers to achieve a look similar to particle board and other engineered woods. Typically, wood fillers come in a neutral colour that you can dye before using. Add any colour or mixture of tints to match any natural wood colour. Wood filler starts to dry within 10 minutes of application, and will typically be ready for sanding and finishing in less than 24 hours.
Wood filler has a variety of uses. Latex filler is one of the most commonly used fillers, because it is water-based, offers convenient clean-up, and easily mixes with dye pigments and texture additives. Use latex filler to seal cracks and holes in unfinished wood floors. Polyurethane filler works well with pre-finished flooring and wood, because it is mixed with a polyurethane seal that acts as a protective barrier. Lacquer filler works well with lacquered wood. It is the only filler that will bond with a pre-lacquerd surface. Epoxy filler works well with unfinished woods. Epoxy filler dries hard, and requires a high level of sanding, which would ruin the finish on sealed floors. Wood filler cannot be used as a glue to bond wood together, because it has no adhesive properties.
Wood putty, which is made from calcium carbonate and linseed oil, comes in a variety of colours and is easy to match any colour of wood with dye pigments. You can purchase wood putty pre-dyed at the store, or buy the putty and dye pigments separately to dye it yourself. Although it's widely used, wood putty has an extended drying time, which can make it difficult to work with and more limiting than wood filler. For example, it can take anywhere from 48 hours to more than two weeks for wood putty to completely cure. Wood putty also only works with oil-based finishes, which also limits its uses. It does, however, last longer in the container than wood filler, which makes wood putty more cost-effective over time.
Wood putty has many of the same uses as wood filler. Used to fill cracks, knotholes and seams in unfinished or finished woods, wood putty does have some adhesive properties, and can be used to glue small pieces of wood together. If wood putty is used on finished woods, it must be dyed the correct colour and kept free of traffic while it dries to avoid over-darkening. When used on unfinished woods, colour matching is less important.
The texture of wood filler and wood putty is essentially the same. Wood filler can become harder than wood putty, especially the epoxy version. Overall, both wood filler and wood putty have a consistency similar to that of thick peanut butter when wet and dry to a spongy or semi-hard finish. Wood putty leaves a small amount of oil residue after drying that must be washed away. Some wood fillers will dry and crumble if not covered in another seal.