Ebonizing Wood

[Cagey]

I found this while searching for something else, and thought some of you might find it interesting...

It’s hard to improve on the natural beauty of wood with all its various hues and grain patterns. For that reason I generally prefer a natural oil finish to just about anything. But there are occasions when there is already too much of a good thing in one space. I occasionally like to see black chairs around a particularly striking tabletop or a black frame showcasing woven hickory bark in the back and seat of a chair. For whatever reason I decide to ebonize, I prefer to do so naturally. I have tried ngr (non-grain-raising) stains, aniline dyes and oil stains and they all have their advantages for specific situations. But for depth and durability, I prefer ebonizing with iron.

I have been experimenting with using iron to stain wood for more than 20 years. I have read a little bit about it, but most of what I have learned came through experimentation. Iron staining, or ebonizing, generally uses a reaction between iron oxide and the natural tannins in wood to create a natural- looking black that is actually created in the fibers of the wood rather than a stain sitting on top. This is why it is so durable. It is integral, not superficial. I have also found it to be very light-fast.

Continue reading...

 

[mayfly]

wow that's cool.  I wonder what that would look like with walnut.

 

[Cagey]

Dunno. Apparently, it relies on high-tannin woods to work, so that would be stuff like oak, mahogany, cherry... not sure where walnut fits in that group, if at all.

 

[bagman67]

Dunno specifically about walnut, but I suppose if you want to do this with any wood low in tannins, perhaps you could treat it with tannic acid before applying the iron reagent.

 

[mayfly]

Just read the article - they say that walnut works.  Very cool in any case. 

I don't need another guitar, but I wonder how toll paint sticks to the resulting surface...

 

[bagman67]

Just read the article - they say that walnut works.  Very cool in any case. 

I don't need another guitar, but I wonder how toll paint sticks to the resulting surface...

Clearly I hadn't read the article before responding - it basically expands on artful use of tannic acid in various forms to get a usable shade of black.  I'd like to think I'm a guy who can be bothered to READ before I pop off, but apparently I'm not that guy today.

 

[Cagey]

Just read the article - they say that walnut works.  Very cool in any case. 

I don't need another guitar, but I wonder how toll paint sticks to the resulting surface...

Since it's not a finish, per se, I imagine you can put whatever you want on it. You're basically just getting the natural pre-existing tannins to oxidise. If there was a problem with that, there'd probably be a problem with the natural wood that hasn't been flipped.

Not having heard of toll painting, I looked it up. It's tole painting. According to this article, surfaces are sealed, primed and sanded before you do your thing. They do mention using a black base. I also recognized it as the technique you've used on some of your instruments. Learn a new thing every day, eh?

 

[Patrick from Davis]

I believe that this is what is historically know as Iron Gall Ink.  The link is in the words.  It is not oxidizing the acids, that would be difficult with out destroying them, but getting Fe2+ to be sequestered by them.  There are problems, but the wikipedia article has them summarized nicely.
Patrick

 

[stubhead]

Well, I never said there wasn't something wrong with me - I got stuck at the part with me, at the stove, boiling wads of rusty steel wool in vinegar. "Hi Honey, I'm home! Ummmm.... that's for dinner?"

Iron gall ink had the nasty habit of reacting with stuff in the paper it's been used on, and eventually dissolving and eating through the paper. I'd guess it just kept on reacting - paper is wood or cotton anyway. It was a cheap and easy ink to make, aniline dyes had yet to be discovered, but it made for a lot of problems when people went looking for land deeds and title searches and instead found a pile of dust, right where your rich aunt Winifred's will used to be. For a guitar, it would be an interesting experiment to sweat on it with your naked forearm, lock it up in an airtight case, repeat, observe...

 

[Cagey]

For what it's worth, Wikipedia has this to say about that...

While a very effective ink, the formula was less than ideal. Iron gall ink is acidic ranging from roughly equivalent to a lemon to that of a cup of coffee. For this reason some makers of iron gall ink used crushed egg shells (which contain calcium carbonate (CaCO3)) to temper the ink, bringing it closer to a neutral pH value. Depending on the writing surface being used iron gall ink can have unsightly "ghost writing" on the obverse face of the writing surface (most commonly vellum or paper.) Also any excess of ferrous ions remaining in the ink, over years, decades and centuries, could create a rusty halo around the marks and ultimately it would eat holes through the surface it was on.

Paper has its own special problems with iron gall ink. The iron-tannic pigment did not make chemical bonds with the cellulose fibers. The ink stuck firmly to the paper, but largely by mechanical bonding — namely, the dried ink penetrated the spaces between the fibers and, after drying, became entangled in them. The process of decaying the writing surface is accelerated on paper when compared to vellum, doing the damage in decades or years that could take more than a millennium on vellum.

The acidity of iron gall ink is well known but it must also be observed that the case for the acidity of iron gall ink is somewhat overstated. There are several thousands of manuscripts, some of them well over 1,000 years old, with iron gall ink on them that have no damage or degradation whatsoever from the iron gall ink. This understanding however should not be taken to ignore the potential issues of documents that use iron gall ink for the writing.

So, I guess if it was me, I wouldn't worry about it. They do use the technique to stain furniture, after all. If it had such a deleterious effect on wood or cellulose fiber that it could be a practical problem, it would never have found use in that industry.

 

[swarfrat]

[quote author=StubHead] For a guitar, it would be an interesting experiment to sweat on it with your naked forearm, lock it up in an airtight case, repeat, observe...
[/quote]

Paging Max's unfinished maple neck.

 

[Patrick from Davis]

A little baking soda in water would neutralize the acid.  Fizz a little, but if you were worried about the pH...  The end products of the reaction are CO2 and a salt depending on the acid.
Patrick

 

[Mor Paul]

[quote author=StubHead] For a guitar, it would be an interesting experiment to sweat on it with your naked forearm, lock it up in an airtight case, repeat, observe...

Paging Max's unfinished maple neck.
[/quote]
No airtight case, but maybe I'll get a picture soon.