Flexner on Finishing: Understanding Wood Finishing

1511-2-01_Oil and VarnishHere are four things you need to know.

by Bob Flexner

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Finishing is not hard to understand. As I’ve pointed out in previous articles, it’s made confusing by manufacturers who don’t understand their own products, so they make up names and claims they think will help sell their wares.

The manufacturers who are most guilty of this are the ones who target do-it-yourselfers and small shops – you. Finishing will never make sense until you get past this mislabeling.

Here are the four basic topics you need to understand to make sense of finishing.

Oil Finishes

Oil finishes are very popular because they are easy to apply. The two common straight-oil finishes are boiled linseed oil and tung oil. Tung oil takes longer to dry than boiled linseed oil, but dries faster than raw linseed oil (which dries too slowly to be useful as a finish).

Tung oil wrinkles when it dries, even when all the excess is removed. To get a smooth result, you need to apply five or more coats, sanding smooth between each and allowing each to dry for two or three days in a warm room. Coats of boiled linseed oil can be applied every day and the results are always smooth when the excess is wiped off.

Both these oils can be combined with alkyd or polyurethane varnish in any proportion to make an oil/varnish blend. This blend might dry a little harder and be a little more water-resistant than straight oil, but only a very little because the application is so thin.

Articles: You’ll find many free finishing articles on our web site.
In Our Store: “Flexner on Finishing” – 12 years of columns illustrated with beautiful full-color images and updated, and “Wood Finishing 101.”

From the December 2015 issue

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