Wednesday, January 29, 2014

Ebonizing Wood



One way to make your woodworking stand out is to invest some time in learning new finishing techniques. Ebonizing by the method I describe here is a great addition to the thousand-dollar shop, because it requires no special equipment or tools other than the plastic cups, gloves, rags, etc. you already have on hand.
The materials to finish a dozen chairs can be purchased for under $20. The results look like a million bucks if you do this right. This method gives better results than using black aniline dye or india ink or RIT dye, all of which I've tried. As with any finishing technique, I BEG you to practice on scraps before you do it on a major project. And keep samples of the finish on hand for future reference.

Recently I built a ladderback chair out of birch and realized I wanted the finished chair to be much darker than the Waterlox I usually use would make it. I have used an ebonizing method involving steel wool and vinegar in the past, with results that varied from spectacular to mediocre, but I knew that birch has little if any tannin naturally. I also knew that it is possible to pre-wash wood with tannin, then use the vinegar/iron wash, but wanted to learn a bit more before I tried it, to avoid reinventing the wheel. So like any lazy 21st-century hack, I looked online. The best article on ebonizing with this method I turned up was written by Brian Boggs and appeared in Popular Woodworking in 2009. You can read it online, here: http://www.popularwoodworking.com/techniques/ebonizing_wood , however the online version of this article is text-only, and includes no illustrations. So I photographed the process of ebonizing my birch chair, which I thought went pretty well, as a supplement to the Boggs article. The following photos are meant to illustrate the process Boggs describes. I'll sketch out the process in my captions, and call out any points where I differed from what he describes.

 Above: one pad of steel wool has been washed in hot water and dish detergent, rinsed with hot water, shredded, and stuffed into a half-gallon milk jug, into which I then poured a quart of Heinz distilled vinegar. This photo is taken a day after the soaking process began. You can see bubbles of hydrogen. Boggs says to bore a hole in the cap to let this vent; I found that leaving the cap loose was enough to prevent pressure buildup.




Here's the finished vinegar/iron wash. After a week in the vinegar, the iron was completely dissolved. I lined a funnel with a coffee filter and poured the iron wash into a clean glass jar. Here I've put a few drops on a white plate so you can see the reddish brown color. This stuff will stain things like paint and formica, so be sure to wipe it up right away if you spill any!





And here is the quebracho bark tea. It's much quicker to make than the vinegar wash; you simply stir some of the powder into very hot water and it's ready to use. In Brian Boggs's article he lists a taxidermy supplier as his source, but I bought my quebracho bark powder from http://www.shellac.net/Dichromate-Tannin.html because they sell it in smaller, half-pound quantities. I think the small packet I got will serve me well for years.





Take a bit of extra care in removing the sanding dust. Here I use a wide paintbrush (dry) along with my vacuum. I sanded as directed in the article. One point Boggs emphasizes is that you want to avoid burnishing the wood. Too much pressure, and sanding to a too-fine grit can cause this burnishing, which prevents the washes from penetrating the wood deeply enough.



The chair ready for finish. This is the natural, unfinished color of paper birch. I include it for comparison with the washed results.






Above is the chair after the quebracho bark wash. This was the biggest surprise of this process, for me. I didn't expect such a nice brown color to come simply from the tanbark! So in the future I might test this as a finish for light woods on its own.


Above is the chair after the vinegar wash has been applied. It is very dark, but with hints of blue and green rather than truly black. The article says that true black comes after a second quebracho bark wash, so I gave it a try:






 Fantastic! I'm a believer.

In the article, Brian warns against letting the two washes touch each other anywhere other than on the wood, because they'll react with each other outside the wood and lose their potency. I was very careful about this. I used two separate cheap paintbrushes, one for each wash, and frequently rinsed them with clean water to be sure I didn't start getting the washes reacting with each other in the brush.

I let these washes dry for several days, pinned the back slats with dogwood pegs, then finished with Waterlox as usual. Here's the finished chair, complete with a riveted leather seat:







3 comments:

  1. Beautiful chair! and thank you for the step by step visual. It really helps! and yes, the brown from just the tea is lovely, too.

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    1. Thanks! If I ever try just the tea wash, I'll post photos here - - or you could try it and send me photos!

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