New paper on ebonizing wood with iron acetate

[John Whitley]

I just happened across this recent paper (2023 Jan 30!) in the Journal of Wood Science, Iron acetate solution prepared from steel wool and vinegar for ebonizing wood by Robert Q. Thompson. It’s an open access publication, so the entire work is available on the web as well as via PDF download at that link.

This is the first really rigorous dive into the chemistry and application of iron acetate for ebonizing wood that I’ve found. There are a lot of details that will only interest those with a chemistry background, but there are definitely process tips that refine or even upturn commonly cited practices in the woodworking world. An example:

“Steel wool usually has an oil coating that you’ll need to remove before making the solution.” The reaction rate is not significantly changed upon washing with detergent and water or rinsing in nonpolar solvent.

or this one:

“Let the steel wool and vinegar sit for a week.” An effective iron ebonizing solution can be created in just 3 days.

Readers can fast-forward to the practical details in the “Conclusions” section, where the author provides a nice summary of where the study improves on the common folklore.

 

[Tom Gall]

This is a very old process. Our club had a demonstrator (can't remember her name - from a Scandinavian country?) more than 20 years ago. She mixed a batch at my house and used it at the meeting 4-5 hours later, but longer is better. I think I still have a jar of it somewhere - probably really bad by now. I believe it works best on woods with a lot of tannin.

 

[Walter Mooney]

John,
I’m sure glad you found that. While the majority of the paper was quite “scientific” in nature (and wording), the author’s final, scientific conclusion couldn’t be more clear, and in layman’s terms no less! And he debunked so much of the ‘knowledge’ that‘s out there on this process. I’ve saved the pdf of it, and I’m especially glad to know that the old steel wool I have sitting around is the perfect steel ingredient in the solution! Thanks again for finding it!

 

[John Whitley]

This is a very old process.

Thanks Tom. That's precisely why I find this paper so interesting. The author went to pains to clarify and demystify an old process. Humans accumulate folklore like a sock under the dryer accumulates lint. Some of that folklore is wisdom of experience, some is wisdom but the motivating reasons have become lost, and some is just ... the lint. ;-) Work like this refreshes this knowledge for future generations.

 

[Bob_Mitchell]

This is indeed valuable. I’ve bounced around different bits of advice in the past with mixed results. Having a tested formula and application guidelines should eliminate a lot of guesswork. Washing steel wool always seemed kind of absurd; glad to know it’s not necessary.

 

[robo hippy]

I think Mike Mahoney did a comparison of the vinegar/steel wool process and the ammonia fuming process, and he liked the color of the ammonia fuming better. Can't remember for sure... I think it is a far more difficult process. Any one know or can compare? I have some white oak I plan to use for furniture sitting around....

robo hippy

 

[hockenbery]

Playing with home brews can be fun for a while.

when I want an ebony black wood.
I use fiebings usmc black leather dye. I wear nitril gloves and paint it on with a foam brush.

citrus ball.

failed experiment the leather dye on cherry bled under the masking


black airbrush paints on cherry leaves a crisper outine

I have airbrushed the leather dye with good results over a mask but need a respirator so I prefer the airbrush paints

 

[R Henrickson]

I think Mike Mahoney did a comparison of the vinegar/steel wool process and the ammonia fuming process, and he liked the color of the ammonia fuming better. Can't remember for sure... I think it is a far more difficult process. Any one know or can compare? I have some white oak I plan to use for furniture sitting around....

robo hippy

I much prefer fuming white oak. Vinegar/steel tends to yield an essentially black surface. It's often referred to as ebonizing. I used it and I don't like the uniformity of color and the effective obliteration of features of wood, particularly any variation in shade. Fuming, on the other hand, darkens the wood but does not conceal the fact that the material is wood. Subtle variations in shade and color remain, often enhanced. It is not as straightforward as vinegar/steel, which simply yields a black surface. Fuming can produce quite variable results, even in a single plank. Varying amounts of tannin affect the degree of darkening. Sapwood does not respond well. Red oak also does not respond nearly as well. Fuming requires significant tannin in the wood.

I have fumed a lot of white oak. It is not difficult. Most instructions dictate high strength ammonia (25%), and usually are old enough to suggest getting it from your local blueprint business(!) They also warn that it is dangerous at that strength and advise various precautions. That strength is NOT necessary. I have used only household ammonia, with great success. It does the job well and merely reeks without endangering your health. I put a couple cups in containers in a medium plastic tote. Within 24-48 hours the white oak will darken markedly. Rather than concealing the grain, it tends to enhance it while darkening. An additional benefit -- even in that time, the darkening will penetrate deep below the surface -- usually 1/16" or more. In that it differs from stains, paints, and ebonizing with vinegar/steel. It would, however, be well to test samples from the wood you intend to use to see how those particular planks react. It would be best to use planks from a single tree. If not, perhaps test a small piece from each plank. Again -- household ammonia is entirely adequate for fuming. It may take a bit longer, but you can breathe. I do my fuming in the basement.

 

[Hugh]

Another source for the 25% ammonia is from a farm fertilizer supplier.. They call it "Aqua" .

 

[Bob Sheppard]

This is a very old process. Our club had a demonstrator (can't remember her name - from a Scandinavian country?) more than 20 years ago. She mixed a batch at my house and used it at the meeting 4-5 hours later, but longer is better. I think I still have a jar of it somewhere - probably really bad by now. I believe it works best on woods with a lot of tannin.

I remember that demo, but can't remember her name, either. Wasn't that when we were meeting at the church?

 

[Tom Gall]

I remember that demo, but can't remember her name, either. Wasn't that when we were meeting at the church?

Hi, Bob. Yes, it was at the church. Dave Ellsworth dropped her off at my house in the afternoon. She prepped for the demo in my shop ... I took her to dinner ... and then we headed to the meeting. After mulling it over the name Irene Grafert comes to mind - but I can't find any info to prove that.

 

[Bob Sheppard]

Hi, Bob. Yes, it was at the church. Dave Ellsworth dropped her off at my house in the afternoon. She prepped for the demo in my shop ... I took her to dinner ... and then we headed to the meeting. After mulling it over the name Irene Grafert comes to mind - but I can't find any info to prove that.

Your memory is better than mine. Even that name doesn't jog any brain cells.

 

[hughie]

Hi, Bob. Yes, it was at the church. Dave Ellsworth dropped her off at my house in the afternoon. She prepped for the demo in my shop ... I took her to dinner ... and then we headed to the meeting. After mulling it over the name Irene Grafert comes to mind - but I can't find any info to prove that.

Decorative Woodturning Irene Grafert

 

[Tom Gall]

Decorative Woodturning Irene Grafert

Thanks, Hugh ... that's her! I searched the AAW site for membership and for articles, etc. I know she has had photos and maybe an article or two in the Journal. But I came up empty.

 

[Tom McDonnell]

On one of the craft shows on PBS a woodworker ebonized maple by painting first with a tannic acid solution.

 

[Oliver Moss]

Fantastic resource, I really appreciate it.

 

[John Whitley]

[...]
Most instructions dictate high strength ammonia (25%), [...]That strength is NOT necessary. I have used only household ammonia, with great success.

This is good to know, thanks. I suspect that the high strength recommendation, based on some practical sources I've run across, may also derive from users fuming larger furniture projects, outdoors, in an enclosure that's not terribly well sealed compared to a plastic tote. (And deploying the 25% ammonia while wearing a respirator, full face shield, and with a big fan to create a "tailwind" behind the woodworker!)

 

[Neil S]

Fuming, on the other hand, darkens the wood but does not conceal the fact that the material is wood. Subtle variations in shade and color remain, often enhanced. It is not as straightforward as vinegar/steel, which simply yields a black surface. Fuming can produce quite variable results, even in a single plank.

I also prefer to fume for the reasons you give.

Another source for the 25% ammonia is from a farm fertilizer supplier.. They call it "Aqua" .

My brother-in-law sold bulk supplies of aqua ammonia for use in agriculture and he had a near fatal experience from a spillage. If you are using a concentration of 25% take the warnings and precautions very seriously.

In my experience the household concentrations are adequate if there are sufficient tannins and you give it time. As Tom points out, if the wood is low in tannins you can boost that up by steeping in tannin rich solutions like black tea. There are other sources of tannins like wattle (acacia) bark, chestnut and oak. Turmeric has much lower level of tannin, but gives warmer tones.

 

[Rusty Nesmith]

Since ebony is so expensive my friend makes finials out of other woods and turns them black with India ink. They look great.