The Art of Coloring Wood: A Woodworker’s Guide to Understanding Dyes and Chemicals (Linden Publishing, 2017), by Brian Miller and Marci Crestani focuses on the unique coloring characteristics of six popular woods used by woodworkers. The book is a perfect starting point for anyone interested in learning the art of coloring wood. The following excerpts are from Chapter 15, “Introduction to Natural Dyes”; Chapter 16, “Brazilwood”; and Chapter 19, “Walnut Crystals.”
Introduction to Natural Dyes
No doubt woodworkers were inspired centuries ago to try coloring their wood with natural dyes after observing the range of hues they imparted on fabrics. We tend to think of natural dyes as coming from plants, but of the four most popular dyes used to color wood nowadays, two of them, brazilwood extract and logwood extract, are derived from the heartwood of trees, one is derived from the husk of a nut or from peat (walnut crystals) and the fourth, cochineal, is actually a bug.
Like chemicals, natural dyes get a color boost from tannic acid. Unlike chemicals, however, they will still deposit a more colorful shading (as opposed to the weathered effect of chemicals) on wood that does not contain tannins.
The main advantage that natural dyes have over synthetic dyes is that they are more light fast when used in conjunction with a mordant. So before you get too excited about the prospect of coloring your wood in a more natural way than using chemicals, let us explain the concept of mordants.
The word “mordant” comes from the Middle French word “morder” which means “to bite.”
A mordant is the fixer that helps the natural dye’s color bite more firmly into the wood’s fibers…or you could say, the mordant binds the color to the fibers. Chemicals are the mordants for natural dyes. The most common chemicals used as mordants are potassium dichromate, ferrous sulfate and alum. If you want to use a less toxic chemical as a mordant, try sodium carbonate and see if you like the results. Mordants are not essential for all natural dyes, as you will see in two of the following recipes (brazilwood and walnut crystals).
When chemicals are used as a mordant with natural dyes, tannins are not essential. Chemicals will still bind the natural dye to the wood even if the wood does not contain tannins.
If tannins are indeed present, though, the chemical mordant will do more than interact with the dye color and help bind the color of the natural dye to the wood fibers. Now the chemical will add an additional twist to the final color because of the chemical’s reaction to the tannins.
The traditional method of application is dye first, followed by a chemical mordant. If, however, you are adding tannic acid to the wood (yet another variable on species like alder and maple that contain little to no tannins), you would begin with the application of the tannic acid solution and–after the wood is completely dry–proceed to applying the dye. However, there is no need to re-apply the tannic acid solution before adding the chemical.
Because you dissolve natural dyes in water, use a synthetic brush to apply them. They are typically non-toxic but they will stain your skin, so wearing gloves is a good idea.
You can see that the intersection of chemicals and dyes vastly widens your choices for coloring wood. The combinations presented here are some of our favorites but feel free to experiment, and even design your own signature combination!
Recipe for Brazilwood
• 1 teaspoon of Brazilwood extract
• 2 ounces of hot distilled water
• 2 ounces of cold distilled water
1. Slowly stir one teaspoon of brazilwood extract into two ounces of hot distilled water.
2. Add two ounces of cold water and stir thoroughly.
3. Strain into a clean container.
4. When the solution comes to room temperature, apply to the wood, maintaining a fifty percent overlap.
5. Wipe off any excess solution.
6. When the wood is completely dry, apply one coat of finish before lightly sanding off any nibs.
Recipe for Brazilwood and Ferrous Sulfate
• 1/8 teaspoon of ferrous sulfate
• 3 ounces of hot distilled water
• 3 ounces of cold distilled water
1. Follow the recipe for mixing the brazilwood solution.
2. After you have applied this solution to your wood and it is completely dry, apply the ferrous sulfate. (See Ferrous Sulfate recipe above)
3. Do not sand until after the ferrous sulfate and a first coat of finish have been applied.
4. Slowly stir the ferrous sulfate into 3 ounces of hot distilled water.
5. Mix until thoroughly dissolved and then add 3 ounces of cold distilled water.
6. Mix thoroughly.
7. Strain this solution into a clean container and apply when it has come to room temperature.
8. Wipe the surface with a rag before the solution dries.
Recipe for Walnut Crystals
• 2 teaspoons of walnut crystals
• 5 ounces of hot distilled water
1. Slowly stir two teaspoons of walnut crystals into five ounces of hot distilled water.
2. Stir thoroughly until dissolved.
3. Strain into a clean container. When the solution comes to room temperature, apply with a synthetic brush.
4. Wipe off the excess solution with a rag.
Extracted from The Art of Coloring Wood, ©2017 by Brian Miller and Marci Crestani, published by Linden Publishing.