The Art of Coloring Wood

A Woodworker's Guide to Understanding Dyes and Chemicals

Brian Miller, Marci Crestani

• Publisher: Linden Publishing
• Year: 2017
• ISBN:
  9781610353236
• Topic: Technologie et ingénierie
• Subtopic: Métiers techniques et manufacturiers

Learn How to Use Dyes and Chemicals Like a Pro

If you're a woodworker looking to take your skills–and your next project–to a higher level of craftsmanship, you might want to consider coloring your wood with chemicals and dyes instead of stains. Unlike stains that can trap light and obscure grain patterns, chemicals and dyes, when handled properly, are one of the best methods for enhancing a wood's color or accentuating the grain pattern. A classic technique that's been practiced for centuries, coloring wood is a sure way to infuse a "wow" into your woodworking efforts.

With expert guidance by Brian Miller, a professor of Wood Technology who teaches an actual course on coloring wood, The Art of Coloring Wood removes any and all intimidation of working with chemicals and dyes and is the perfect entry point for anyone looking to move on from simple stains to learn the art of coloring wood for dramatic effect. To keep the information accessible and relevant.

The Art of Coloring Wood focuses on the six most popular woods used by woodworkers–maple, quartersawn white oak, mahogany, walnut, cherry and alder–and outlines the unique characteristics with regard to coloring each. After the six woods are outlined, The Art of Coloring Wood moves onto the supplies needed, including brushes, sandpaper, and much more, before proceeding into the easy-to-follow and engaging chapters on the different chemicals and dyes that will make your woodworking shine. The beauty of The Art of Coloring Wood is Miller's simple approach that makes the chemistry very easy to understand. Each chapter offers recipes, insights, and many "a-ha!" moments that make learning about chemicals and dyes both fascinating and within easy reach.

With the helpful sidebars throughout the book offering tips, mistakes, and countless nuggets of information, The Art of Coloring Wood will have you understanding the methods and many worthwhile reasons for coloring your wood while chomping at the bit to get a project completed so you can finish it with style and flair.

1

How the Art of Coloring Wood Developed

The centuries-old art of coloring wood with chemicals and dyes owes a huge debt to the textile industry. It was craftsmen in the latter trade who developed coloring techniques that were formulated with plant materials, chemicals and/or animal parts.

Some of these old methods may seem outright weird to us nowadays. For example, back in the 1800s, if you wanted to achieve a red color, you were advised to use the intestinal liquor of a sheep, along with its dung and blood. And you were instructed to advise the butcher to stir the blood really well to prevent its coagulating. Animal urine was also a frequent ingredient in dye solutions. If you were dying textiles, you were sometimes further advised to soak the fabric in water containing animal bones in order to make the color more long-lasting.

Historically, wood furniture had been “colored” primarily through decorative inlays of other non-wood materials, such as mother-of-pearl, tortoise shell, ivory, brass, pewter and precious stones for example. Over time, the increasing availability of exotic woods—due to the growth of the worldwide shipping trade—spurred advancement in the art of marquetry, which was referred to as “painting in wood.” Veneers of various exotic woods were cut and pieced together to form pictures.

However, some colors, like blue and green and true red, are just not found in any species of wood. At best they may be discovered in very light shades inside timber when the wood is first cut, but these colors quickly fade after cutting as the wood is exposed to oxygen and light.

As coloring techniques in the textile industry advanced rapidly, the desire to color wood with chemicals and dyes gained momentum. Textile dyers were highly specialized craftsmen. For example, you could specialize in coloring silk while another person would be an expert in coloring cotton. Or else you could be an expert in a particular color, such as red, and you would know how to treat any type of fabric with this color. A sub-specialty of these branches would be to specialize in coloring whole cloth or just the threads or yarns of a particular type of fabric.

While most dyers took their secrets with them to the grave and because books were prohibitively expensive, the art of coloring with chemicals and dyes was largely learned through private practice. General knowledge of which plants or chemicals produced which colors was easy to obtain but the fine art of doing it well was achieved overwhelmingly through individual trial and error.

A Sampling of Historical Plants for Dyes

AMERICAN BARK, aka QUERCITRON produced a yellow color and was obtained from the bark of quercus nigra. Its discovery is largely attributed to Dr. Edward Bancroft in the late 1700s and his name for the dye combines references to its source material (quercus) and its color (citron). Books published in that time noted that the English government passed an Act of Parliament granting Dr. Bancroft the exclusive privilege of using quercitron as a dye. Perhaps explaining this great honor is the fact that decades after his death, Dr. Bancroft was outed by the British government as being a double agent for both the United States and Britain.

Some coloring agents do not produce the same results across all species of woods. They may highlight the red tones on one species and the yellow tones on another.

INDIGO produced many shades of blue depending on the plant variety used. Written recipes from the 1700s and 1800s would often instruct the reader to use “the best indigo.”

MADDER produced a red color. An 1830 recipe for dying a pound of cotton instructed you to thoroughly mix 20 pounds of liquid sheep’s blood in a kettle of water before adding two pounds of madder.

SAFFLOWER produced both yellow and red colors, depending upon which plant variety was used for the source material. The yellow color was sometimes referred to as “bastard saffron.”

TURMERIC produced a yellow color but it was referred to as a “fugacious” (fleeting) color. Dyers were known to add a little dragon’s blood to the solution to tame the intense yellow. The name “dragon’s blood” is more dramatic than its actual source. It is a resin that comes primarily from the treelike dracaena plant and was often used for medicinal purposes.

BRAZILWOOD and COCHINEAL were also used extensively as a red dye, and we cover both in this book. Unlike our recipes for these dyes, recipes from the 1700s and 1800s called for extra ingredients. To cochineal they added the intestinal liquor of the sheep, along with its dung and blood. Their recipe for brazilwood was bolstered by dissolving the dye in stale urine. Don’t worry—we prefer using distilled water.

A Sampling of Historical Chemicals for Dyes and Mordants

Chemicals were used primarily—but not exclusively—as mordants in previous centuries. (We discuss the role of mordants in Chapter 15 of this book.)

A mordant is a chemical that “fixes” a dye in the wood. The most popular chemical mordant was ALUM (also known as aluminum potassium sulfate).

AMMONIA, NITRIC ACID, and IRON ACETATE were all used for centuries to color wood and we cover them in this book.

COPPER produced a greenish shade to use on light-colored wood. Historical recipes from the early 1800s call for the dyer to expose copper plates to the husks of grapes, which are high in acetic acid. A bluish-green rust develops on the plates and this rust (called verdigris) is scraped off and used as the dye. It was widely agreed that the best verdigris is made in France. Hmmmm . . . any relation to the widely held notion that the best wine also comes from France?

COPPERAS is now widely known as ferrous sulfate (which we cover in this book) but in books from the 1800s it was considered to be too well-known to need description! It produces bluish/grayish tones.

SULPHERET of ARSENIC produced a yellow color. We think there are plenty of more pleasant ways to achieve a yellowish color.

TIN produced a scarlet color when dissolved in nitric or muriatic acid, according to books from the 1700s.

While the use of plants and chemicals as dyestuff remains current, the use of animal parts in the coloring process for wood has died off over the years. Excuse the pun.

2

Wood Samples

The funny thing about woodworkers is they typically have very decided tastes on which woods they like. . . . and even more decided tastes on which woods they don’t like! We debated which six species should be the “guinea pig” samples for the coloring processes presented in this book and decided upon maple, quartersawn white oak, mahogany, walnut, cherry and alder. These woods are probably the most consistently popular with woodworkers across the country and across a variety of design styles.

Now there are a few considerations in choosing a coloring treatment for wood.

Three of the species in this book—oak, mahogany and walnut—are open-grained woods, which means that no matter how highly sanded they are, there will still be open crevices in the wood so that when finish is applied, there will not be a glass-like smoothness and sheen to it. If you were to run your fingernail across (rather than with) the grain pattern, you will find that it catches in the crevices. This feature expands the choices you have in ways to color your wood—for example, you can do grain filling!

Another aspect of wood to take into account is how UV stable it is. Over time, wood either lightens or darkens to varying degrees as it is exposed to light and polishes. Wood does not necessarily have to be in direct sunlight for these color changes to occur. The aging process that shifts the color of the wood is called patination. You may have heard of someone referring to an antique piece of furniture as having a “beautiful patina.” This means that the wood has developed a deeper, richer coloration that imparts a sense of history. Even the tones on the simplest of woods—such as pine, for example—will become heartily enhanced over time through patination. Chemicals and natural dyes will instantly lend a patinated effect to wood.

Mahogany, cherry and walnut are relatively quick to patinate—with mahogany and cherry going darker and walnut lightening over time. Oak, alder and maple are the most UV stable in this group of six. Consequently oak, alder and maple tend to patinate more slowly but they all do eventually darken as they age. Chemicals and dyes will not prevent lightening or darkening from occurring. Therefore, you should always consider the background color of the wood and in which direction it will patinate over time in choosing a coloring process—and in deciding how strong to make your formula.

One of the most prized features in wood is when it has chatoyance. This refers to a radiant, shimmering effect in which undulating rays of light seem to ripple across the grain, and these rays appear and disappear depending on the angle from which you view the wood. Chatoyance is amplified with chemicals and dyes, but deadened with stains because the pigments in stains trap the light.

The downside of some woods is that they are prone to blotching. Even though they are closed-grained woods, cherry and maple will have varying densities within their cell structure which means that these species will absorb liquid unevenly. This leads to notably darker patches in what is referred to as the “softer” part of the wood.

Some people think blotching adds a more “real” look to the wood, highlighting its character. And then there are others who regard blotching as a disappointing mistake.

Fortunately there is no shortage of advice on how to prevent it. The blotch issue provokes as much passion amongst woodworkers as the chili issue does amongst cooks. And everyone thinks their way is the best. You can go online to one of the woodworker forums for a range of ideas. The typical way to prevent blotch is to pre-treat your wood with a thinned-down version of your finish coat before applying chemicals or dyes. Brian typically does not pre-seal the wood to prevent blotch if he is applying chemicals or water-based dyes. However, he will do it if he is applying a stain because stains will make blotch much more apparent.

Another issue to consider when coloring wood is the presence of sapwood, which is the newest growth found directly under the bark. Obviously all species have sapwood, but its presence is more visually dramatic in walnut and cherry because sapwood is significantly lighter in color in contrast to the inner, older heartwood. Some woodworkers cut away the sapwood and use it for less visible aspects of a project, like the bottom of a drawer for example.

If sapwood is present on the outside of a project, though, you should know that it will not accept chemicals the same way as heartwood because sapwood does not contain tannins, which is what chemicals react to. (This issue is more thoroughly discussed in the Introduction to Chemi...