Like most woodworkers, I’m in love with the natural beauty of wood. Accordingly, I tend to favor a simple hand rubbed oil finish to best show off the hues and grain patterns of the easels that I build. However, I also recognize that some artist studios are better equipped with sleeker, more modern furnishings.
So after much experimentation, I’ve settled on a process for finishing some wall easels with a deep, lustrous black finish. Rather than a stain or paint, this appearance is the result of a chemical reaction between iron acetate and tannins naturally present in some species of wood (red oak, in this case). This process is called ebonizing. Whereas opaque stains and paints create a closed surface that obscures the wood, ebonizing leaves an open surface, allowing the wood grain to remain visible.
In theory, the process of ebonizing wood is pretty straightforward — dissolve some rusty nails in vinegar, then apply this solution to the wood. In a matter of minutes, the wood turns dark. In practice, there’s quite a bit more effort involved to achieve a satisfying result.
While some pieces of oak may turn quite black when wiped with iron acetate, others might be limited to a chalky gray. To obtain a more uniform black, I use a couple of tricks. First, I increase the tannins by applying a solution of water and quebracho tree bark powder (a material used primarily for tanning animal hides). Secondly, I apply a water-based aniline dye to further deepen the effect. When wood has been dampened, its soft grain swells and raises, resulting in a rough surface. This means that extra sanding in between applications is in order to maintain a nice smooth surface.
Once the parts have all been ebonized, I assemble the easel and then wipe it down with a few passes of danish oil (polymerized linseed oil with a light varnish). This makes the surface of the wood more durable, easier to clean and provides a nice satin sheen.
Because this process is quite time consuming, I only plan on making a limited numbers of easels with the ebony finish. However, it can be requested for an additional cost.