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AW Extra 2/14/13 - Tips for Finishing Walnut

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Tips for Finishing Walnut

There's no denying that most walnut looks great with nothing more than a few coats of oil. Here we’ll show you some tricks to make your walnut projects look even better.

by Jeff Gorton


Make Sapwood Disappear

Even select walnut boards are likely to contain an occasional streak of light-colored sapwood. Some projects benefit from the contrast provided by skillfully placed sapwood, but in most cases it’s merely a distraction. If you can’t afford the luxury of avoiding all sapwood, we’ll show you how to make it less conspicuous. Even though the initial investment for dye, shellac and glaze materials will set you back about $100, most of these products are highly concentrated and should last you many years.

Dyeing sapwood looks paint-by-number simple but there are a few tricks. The key to the process is getting the dye color to match the heartwood color. Don’t bother with dyes labeled “walnut.” Buy red, blue, yellow and black water-soluble dye powder and custom mix a sapwood. We gradually adjusted the color of the dye by adding drops of blue and black to reach the purplish gray hue of kiln-dried walnut. An eye-dropper works great for this. Air-dried walnut has more red. Adjust your dye accordingly using the Color Mixing Chart provided here as a guide.

We’re using water-soluble dye because it resists fading in sunlight better than alcohol-soluble dye and is easy to apply without leaving lap marks. One drawback, however, is its tendency to raise wood grain. Minimize grain raising by wetting the wood, letting it dry, and sanding off the raised grain with 220-grit sandpaper before applying the dye. Don’t sand too much or you’ll expose new wood and negate the effect.

Here are a few more tips for working with watersoluble dye:

- Wet the end grain before dyeing it to keep it from soaking up too much dye.

- Start with a diluted dye; you can always increase the intensity of the color by adding a “layer” of more concentrated dye.

- Adjust the color by adding another layer (refer to the Color Mixing Chart). Wipe on green dye to decrease red, for example.

- The color you see when you apply the dye to the wood is close to the color you’ll end up with. The wood will look dull when the dye dries, but the “wet” color will return when the finish is applied.

- Lighten dyed wood by wiping off some dye with a damp rag. If you really goof, use household chlorine bleach to remove almost all of the dye.

Allow the dyed wood to dry completely, usually overnight. Then seal the entire surface with a thin coat of brushed on shellac (about a 2-lb. cut of super-blonde or other dewaxed shellac). Allow the sealer to dry and sand it lightly with 320-grit sandpaper. If you’re happy with the way the sapwood blends after the sealer is applied you can move on to applying the final coats of finish. To blend the dyed sapwood more completely, and add greater depth and richer color, apply a thin layer of glaze before applying the final coats of finish.

Glaze is essentially thinned paint that’s layered over a sealed surface. Commercially prepared glazes are available, or you can make your own. Mix up an oil glaze by combining artist’s oil paint (available at art supply stores) with a glazing medium consisting of three parts boiled linseed oil, two parts mineral spirits and 1 part Japan drier, to the consistency of heavy cream. We chose the “burnt umber” color and it looked great. Pick up the following colors as a starter set for blending your own custom colors; burnt umber, raw umber, burnt sienna, raw sienna, Vandyke brown, yellow ochre, black and blue.

Complete the process of blending the sapwood by applying a layer of glaze, as shown in Photo 2. Keep the brush “dry” by removing excess glaze from the bristles with a rag. To add glaze in one section, “stipple” it on with the tips of the bristles and then smooth it. If you make a mistake, remove the glaze using a rag dampened with mineral spirits.

Allow the glaze to dry completely, a minimum of 24 hours, before applying the final coats of finish. Check by running your hand across the surface. If glaze rubs off, it’s not dry.

Click on any image to view a larger version.


1. Use a small artist's paint brush to carefully dye the sapwood, following along the grain line. Blend the edge of the dye into the heartwood with the corner of a damp rag. Dampen the wood before applying the dye.


2. Apply the glaze with a rag or brush. Remove the excess, leaving a thin layer.Then use a good-quality paint brush with soft bristles to manipulate the glaze, adding or subtracting as needed to blend the dyed sapwood into the heartwood.






End Grain Can Be Beautiful

End grain reveals much about a board’s history and provides an attractive detail in many woodworking projects. But too often the end grain soaks up so much finish that the detail gets lost in a dark, muddy cloud of oil or stain. To bring out the full potential of the end grain detail in your next project, seal it with a thin coat of 1⁄2-lb. cut shellac before you apply the stain or oil. Sand the face with 320-grit sandpaper after you seal the end grain to remove any sealer that may have lapped onto it. Then lightly sand the end before you apply the oil or stain.



Matching Old Walnut

As walnut ages its color changes. Matching the cool, charcoal-gray color of new kiln-dried walnut to the mellow mahogany red or amber gold of aged walnut is a challenge faced by anyone who repairs old furniture.

In most cases the new walnut will have to be lightened before adding color with dye. Use two-part wood bleach, available at most hardware and paint stores. This bleach will lighten the walnut without removing all of the reddish tones. Mix and apply the bleach according to the instructions on the containers. Allow it to dry. Then lightly sand the surface with 220-grit sandpaper.

Once the wood has been lightened with bleach, mix dye to match the lightest, most prevalent color of the wood. If you’re matching reddish walnut like ours, use our aged walnut recipe (at right) to mix the dye and then adjust the color to match your project. The process of dyeing and glazing is the same as that for blending sapwood. We left extra glaze in the recesses around the turnings to duplicate the aged finish on the other legs.



1. Bleach your replacement part by mixing two-part wood bleach according to the directions on the label and immediately applying it to the new walnut. Disposable sponge brushes work well for applying bleach. Allow the bleach to dry and lightly sand the surface.


2. Dye the bleached wood to approximate the color of the aged walnut. Err on the light side. Allow the dye to dry.Then seal with a coat of 1-lb. cut shellac, allow to dry and sand with 320-grit sandpaper


Brush or wipe a thin layer of glaze over the dyed walnut. Remove the excess glaze with a rag or dry brush, leaving enough to match the color of the new piece to the aged walnut. Let the glaze dry before applying the final coats of finish.




Warming Up Colorless Finishes

Water-borne varnishes and lacquer are often used on light-colored wood like maple to avoid the “yellowing” that occurs with traditional shellac and varnish finishes. Darker woods like walnut, on the other hand, look better with a “warmer” finish that brings out the rich, dark color.

If you plan on using a water-borne varnish or lacquer finish, consider warming up the walnut first with a coat of dye. We used the aged walnut recipe diluted three parts to one. Allow the dye to dry. Then brush on a sealer coat of a 2-lb. cut of dewaxed shellac to keep the water-borne finish from dissolving the dye. Dewaxed shellac makes an excellent undercoat for most water-borne and lacquer finishes, but check the label to be sure.


Sources

(Note: Product availability and costs are subject to change since original publication date.)

Woodworker’s Supply, Inc.
1108 North Glenn Rd.
Casper, Wyoming 82601
800-645-9292

Woodcraft
210 Wood Cnty. Industrial Park
P.O. Box 1686
Parkersburg, WV 26102-1686
woodcraft.com
800-225-1153

Constantine’s
2050 Eastchester Rd.
Bronx, NY 10461
constantines.com
800-223-8087


Supplies


This story originally appeared in American Woodworker October 1999, Issue #75.



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