This is an excerpt from an article in the June, 2000 issue of Woodworker's Journal.
Picking the "right" finish for your most recent woodworking triumph may seem like a daunting task, given the confusing array of choices. To make the correct choice, start out by answering three primary questions before you begin:
1. How durable does the finish need to be;
2. What kind of appearance do I want; and
3. What's the best application for me?
Durability is the first thing you should determine. Ask yourself, "what must this finish endure." An art turning can get by with nothing more than a coat of oil. A kitchen table or countertop, which needs to endure hot coffeepots, scratches, stains, and even chemicals and strong cleansers, will require something much more durable. Patio and outdoor furniture will need a finish that can stand up to temperature and humidity variances. Salad bowls and cutting boards need a special "salad bowl" finish, which is specifically made for objects which come into contact with food.
Durability is also affected by how thickly a finish is applied. A very thin finish regardless of the type, will not protect as well as a thicker application of the same finish.
Staining, of course, changes the color of the wood, but clear finishes will also alter the appearance of the wood. Most waterborne lacquers and polyurethanes are completely clear to slightly blue-gray. They will add almost no color to white woods such as maple, holly, and spruce. Shellac and lacquer will add warmth and color to the wood. Oils (including Danish Oil, Tung Oil, and oil-based poyurethanes) generally add the greatest amount of amber tones to wood, especially when several coats are applied.
With figured woods, such as curly or bird's eye maple, you can actually use the finish to intensify the figure, or "pop the grain," even without staining. One of the best "grain poppers" around is boiled linseed oil but shellac, lacquer, and most oil-based varnishes will also do the trick.
By adding one or two coats of shellac to a piece of figured wood, you can achieve a stunning effect called "chatoyance," from the French meaning "like a cat's eye." If you've ever seen the semi-precious stone Tiger-Eye, you'll notice that as you change your viewing angle, the light and dark bands of color change places; this is chatoyance.
Most finishes can be applied in a variety of ways. Shellac, for instance, can be wiped on, brushed on, or sprayed on. The same is true of Danish Oil, varnish, and most waterbornes. Some finishes, however, lend themselves more to one application style or another, and others are formulated for a particular application method.
Waxes and gel finished are specifically designed for wipe-on application. Though nearly every varnish or polyurethane can be wiped on instead of brushed on, some are designed for easy wiping and thin application. This will usually be stated on the can.
Certain lacquers and conversion varnishes are designed for spraying and will dry too fast if applied with a brush or rag.
For help choosing the right finish using Dresdner's "Appearance, Durability and Application" approach, see our Finishing Comparison Guide for a product-by-product chart of finish appearance, characteristics and durability.
Michael Dresdner is a nationally known finishing expert and author. This article originally appeared in Woodworker's Journal May/June 2000 issue. For a free trial issue, visit www.woodworkersjournal.com.