How to ebonize wood
Though it pains me to hide all that beautiful grain, I've got a honey-do request for painted black furniture. I'm thinking of using an open-pored wood, like ash, to ensure that the wood grain (and therefore proof of my handiwork) shows through. Is there a traditional ebonizing formula that might let me salvage some woodworking credibility?
—Marshall Greer, Roseville, Calif.
Black furniture fills furniture stores these days, Marshall, so we empathize with your situation. Here are two ways to go about it:
The traditional way (with a modern twist). Start by dissolving a pad of steel wool (historically iron nails) in a quart jar of white vinegar. The iron ions produced by the breakdown of the steel wool react with tannins in wood to produce a black coloration. Stir the brew occasionally over the course of about a week. To avoid a buildup of pressure (the mixture produces a small amount of hydrogen gas), don't cap the jar until the steel wool completely dissolves. Strain the mixture through a coffee filter to remove any undissolved particles.
Alone, this formula works well on oak due to that wood's high tannin content. For other woods, such as ash, you'll get deeper blacks if you artificially crank up the tannin content. First acquire some tannic acid powder from a winery supply company. (We got ours from E.C. Kraus Home Wine & Beer Making Supplies, 2 oz.-jar, Item No. TAN110, 800-353-1906). Stir a teaspoon of the powder into a cup of warm water and apply a wash coat of the solution before and after the vinegar/steel-wool coat. That will give your wood a deep blue/black that will turn a dark ebony upon applying a clear finish.
The quick-and-easy way. Simply apply a coat of India ink from an art supply store with a foam brush, as if you were painting it on. (We used Blick Art Materials' Black Cat India Ink, Item no. 21101-2006, 800-828-4548). It turns the wood a deep black with little mixing, money, or mess while still showcasing ash's prominent grain.