Durability
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. Appearance
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.
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Application
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. |
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| 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. To help you choose the right finish using Dresdner's "Appearance,
Durability and Application" approach, we've made a comparison
guide of all our carefully selected
finishing products. See our Finishing
Matrix for a complete chart of products.
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.
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