Flexner on Finishing: Choosing a Finish for Color


Different finishes look different on different species.
By Bob Flexner
Pages: 70-71

From the June 2009 issue #176
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There are many reasons to choose one finish over another. Usually the most important is for protection and durability – how well a finish protects the wood from moisture and how resistant the finish is to being damaged by coarse objects, heat and solvents.

Other significant factors include drying time (you don’t want a fast-drying finish if you’re brushing) and odor (some finishes have a less irritating aroma than others).

There’s also color. Finishes differ in color, or the amount of color, they add to wood. For example, clear paste wax adds the least amount of color and the least amount of darkening to wood. Wax adds a little shine, but otherwise leaves the wood looking very close to natural.

Water-based finishes don’t add color either, but they do darken the wood noticeably. The lack of color can be an advantage on “white” woods such as maple or ash or a disadvantage on darker woods, making them look “washed out.”

Nitrocellulose lacquer and blonde or clear shellac add a slight yellow/orange tint to wood. But not nearly as much as does orange or amber shellac. (Shellac in flake form is usually labeled blonde and orange. In prepackaged liquid form the equivalent to blonde is “clear” or “SealCoat.” The equivalent to orange is “amber.”)

Oil-based varnish, including polyurethane varnish, and boiled linseed oil add a darker yellow/orange tint than lacquer or blonde/clear shellac. More significantly, varnish and oil continue to darken as they age – boiled linseed oil considerably more than varnish.

Mixtures of varnish and oil, often sold as “Danish Oil,” fall in between varnish and oil in their tendency to darken depending on the ratio of each that is included.


From the June 2009 issue #176
Buy this issue now