Trying to untangle the name and source material of what is commonly known as “walnut crystals” is a daunting task. The term “walnut crystals” is sometimes used interchangeably in the woodfinishing profession with Vandyck crystals or Van Dyke crystals (Van Dyke is the anglicized version of Vandyck.) While the majority of walnut crystals sold come from ground walnut hulls, there are some suppliers who sell peat moss under that name. Most likely they are guided by the final color outcome rather than the actual source material.
Genuine walnut crystals are made from the blackened hulls (also popularly referred to as husks) of walnuts. As a walnut grows on the tree, the nut is covered by a shell and the shell in turn is covered by a soft hull (think of a thin orange peel). When ripe, the hull will turn black when it is removed and air dried—or sometimes the hull falls to the ground and blackens naturally. Either way, the blackened hull is then boiled.
Walnut crystals look like shiny black pepper and are the concentrated dried solution. It is also available as a fine powder or you can even purchase the entire hull for soaking. This is in stark contrast to other dyes that originate from trees in which it is the bark or the sawdust or the chips from the tree that are the source of the colorations.
Historically, walnut crystals have been a mainstay of the world of art rather than the furniture finishing profession. For centuries, the sepia tones produced by the crystals were employed as a popular ink for sketches and drawings. Also the crystals still continue to be used as a textile dye to achieve a mild brown shading on fabrics. However, nowadays they are predominantly associated with the art of calligraphy. Not only is their ink used for decorative handwriting, but it is also applied sometimes as a wash on certain papers to achieve an aged effect.
Natural walnut dye will color your hands quite deeply and will last beyond days, so be sure to always wear gloves when you are working with it. Popular folklore has it that centuries ago, certain cultures stained their prisoners’ hands with walnut ink to readily identify the criminals.
Like brazilwood, walnut crystals are rich in tannins and deposit enough of their own color that they do not necessarily require a mordant, although a mordant would undoubtedly boost or swivel the coloration in a new direction. They are primarily used to deepen the brown tones in wood.
Recipe for Walnut Crystals
2 tsp of walnut crystals
5 oz. hot distilled water
Slowly stir two teaspoons of walnut crystals into five ounces of hot distilled water. Stir thoroughly until dissolved. Strain into a clean container. When the solution comes to room temperature, apply with a synthetic brush. Wipe off the excess solution with a rag.
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Mahogany
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