Thread: How to ebonise box sides

Originally Posted by JillB

Hi Humphrey, good interesting stuff you are doing, but I am now confused between your tannic acid,and the tannins in a strong cup of black tea that you soak the timber in first before applying the ebonising solution. Will the tannic acid have the same affect?

Learnt a bit from your Black Dye link, thanks. The key component in making the ebonising Liquid Nightmare solution is rust, which explains why when Dengue made his solution of vinegar and nicely cleaned steel wool, nothing happened, until he later put in rusty nails and a rusty steel rod.

Perhaps the correct way to make liquid nightmare brew is with steel wool and nails and iron first sprayed with saltwater and left for a few days to rust badly, before immersion in the vinegar?

Hello Jill.

The tannins vs tannic acid thing is a bit confusing. The way I understand it, tannins is the group and tannic acid is a member of that group. The stuff in tea, (but not coffee despite what many claim), is a tannin, but not tannic acid.
Most of my reading indicates that the tannin level in tea is too low to produce good results pre-treating timber for ebonising, although it does have some effect. Tannic acid is a stronger tannin and so is supposed to work better.

Interestingly, persimmons, cranberries, strawberries and blueberries also contain tannins, but I don't know how high the levels are.
Also wine and, to a lesser degree, beer.
Another source is Quebracho bark, crushed then soaked in water to leach out the tannins, similar to using acorns.

Steel wool will work very well and start to rust nicely within hours, (without added nails etc), if only partially covered with vinegar, allowing good air access to speed oxidisation and spraying the steel wool with salt water to speed the process, and what speeds it even more is very regular shaking or stirring, turning over the steel wool and allowing oxygen in. The rusting appears heavier just above the vinegar level, where the steel wool is nice and wet and there is plenty of oxygen.
Oxygen->Oxidisation ... Iron->Ferric Oxide
Pre-rusting is probably even better, but I haven't tried it yet. I get a good result with vinegar/steel wool/salt in about 24 hours.
Audio and video tape is also coated in ferric oxide. Wonder if that would work, and how well?

I haven't tried the tannic acid method before because usually I work the other way around - work out what I want to blacken, then choose a timber that ebonises well, like Jarrah or Red Gum.
Noticeably, too, timbers with a high red/brown content often contain tannins whereas pale timbers don't.

Commercial tannic acid is usually one or a few types of tannin. All tannins are polyphenols, the type of ingredient in many foods like red wine, black tea etc that have been reported to have positive health benefits. The acidic nature of tannins, and why tannic acid is so-called is not because it has a 'typical' acidic group such as a carboxylate like acetic acid, oxalic acid, citric acid etc, it is because it has many phenol groups which give up their H+ reasonably easily (less easily than a carboxylate) so it is a weak acid. The vinegar in liquid nightmare starts the oxidaion of iron to FeII which is quickly converted to FeIII in the presence of oxygen, which is why things underwater rust more slowly than when they are taken out into the air. For liquid nightmare, you can speed up the process by boiling the steel wool in vinegar (this probably helps to remove any coating that might be on it) to begin with, then when the mix cools you can add some hydrogen peroxide to provide an oxygen source. When you paint it onto the wood, the tannic acid coordinates with the FeIII to form a black complex.

Originally Posted by mic-d

Commercial tannic acid is usually one or a few types of tannin. All tannins are polyphenols, the type of ingredient in many foods like red wine, black tea etc that have been reported to have positive health benefits. The acidic nature of tannins, and why tannic acid is so-called is not because it has a 'typical' acidic group such as a carboxylate like acetic acid, oxalic acid, citric acid etc, it is because it has many phenol groups which give up their H+ reasonably easily (less easily than a carboxylate) so it is a weak acid. The vinegar in liquid nightmare starts the oxidaion of iron to FeII which is quickly converted to FeIII in the presence of oxygen, which is why things underwater rust more slowly than when they are taken out into the air. For liquid nightmare, you can speed up the process by boiling the steel wool in vinegar (this probably helps to remove any coating that might be on it) to begin with, then when the mix cools you can add some hydrogen peroxide to provide an oxygen source. When you paint it onto the wood, the tannic acid coordinates with the FeIII to form a black complex.

Thanks mic-d. Sounds like you know a little more about chemistry than I do - what I know would fit on the head of a pin.

Hydrogen peroxide. I should have thought of it. I have some here for sterilising brewing equipment. Tasteless and odourless, unlike sodium metabisulphite.

A question, if you don't mind.
Is it true that hydrogen peroxide, (H2O2), breaks down to water, (H2O), with the freed oxygen molecule being the thing that really does the oxidising? (No harmful residues - just plain old water.)

Originally Posted by Humphrey9999

A question, if you don't mind.
Is it true that hydrogen peroxide, (H2O2), breaks down to water, (H2O), with the freed oxygen molecule being the thing that really does the oxidising? (No harmful residues - just plain old water.)

Yes, but not only. in some cases like with iron, it may break down into hydroxyl ions (quickly converting to water in acidic solution) and hydroxyl radicals and peroxide radicals which are harsh oxidising agents. They do the reacting without molecular oxygen ever being formed as a separate identity.

Originally Posted by mic-d

Yes, but not only. in some cases like with iron, it may break down into hydroxyl ions (quickly converting to water in acidic solution) and hydroxyl radicals and peroxide radicals which are harsh oxidising agents. They do the reacting without molecular oxygen ever being formed as a separate identity.

Thanks again. It's handy to know that it doesn't always break down into pure water.

Originally Posted by Humphrey9999

Thanks again. It's handy to know that it doesn't always break down into pure water.

Remember it mostly never will, unless you decompose a pure solution of peroxide and water. You'll always get the water product but the oxygen is going to be incorporated into whatever poor unsuspecting chemical that is floating around that can be oxidised eg stains on clothes, hair pigment, etc etc...

Originally Posted by mic-d

Remember it mostly never will, unless you decompose a pure solution of peroxide and water. You'll always get the water product but the oxygen is going to be incorporated into whatever poor unsuspecting chemical that is floating around that can be oxidised eg stains on clothes, hair pigment, etc etc...

I was thinking in terms of sanitising clean bottles after washing/rinsing. There's chlorine in the water, (I dilute the 3% H2O2 to 30ml/litre with chlorinated tap water), but not much else.

Sorry for the hijack Jill.

I got a chance to play with my witches brews today - a tannic acid pre-treatment followed by conventional? ebonising. Works great, and on most if not all timbers.
Even a piece of pine, (unknown species), blackened up beautifully, whereas without pre-treatment it turns a horrible, dirty grey.

The tannic acid is labelled tanivin, extracted from Chestnuts, and comes as a brown powder. $3.65 for 25g.

I'm not sure yet of the best application method, and had to guess at the dilution rate. For my first tests, I added 5g of tanivin to 500ml of warm water and stirred until it had all dissolved, then brushed it onto the timber wetly, 2 coats, and let dry. I didn't accelerate drying at all, to allow deeper penetration.


I figured that if I applied the ebonising solution while the timber was still saturated with tannic acid, the solution wouldn't penetrate as deeply, hence the drying time to make 'room' for the eboniser.
When dry, I brushed on two consecutive coats of eboniser. The timber begins to darken immediately.

Depending on the timber/material and the strength of the solutions, more alternating coats of tanivin/eboniser might need to be applied for a darker shade.

I found that brushing on the ebonising fluid while the timber is still wet with tannic acid makes the top surface extra-black for a final coat, since the dye is formed on the surface rather than in the timber.

As a stand-alone dye, the tannic acid and ebonising solutions can be mixed.

Like with water-based dyes, before beginning the process it's a good idea to wipe down the timber with warm water to raise the grain, then sand lightly, but not too hard. If the surface is burnished the solutions have difficulty penetrating. I also sand lightly between rounds of tanivin/eboniser, or following coats tend to roll off and need to be worked into the surface a little at first.

This is really interesting information Humphrey - well done for finding the tannic acid powder and applying it, and many thanks for sharing your findings

I can't wait to get some and try it out

Originally Posted by JillB

This is really interesting information Humphrey - well done for finding the tannic acid powder and applying it, and many thanks for sharing your findings

I can't wait to get some and try it out

Thanks for motivating me, Jill. I've been meaning to try tannic acid pre-soaking for some time.

Further to what I said earlier, too, rather than brushing on, soaking for several hours in each solution would probably work better, but I intend to treat already-glued pieces, so brushing is more suitable.

I also found that a piece of timber can be ebonised, sanded to shape, then re-ebonised to cover the bare area, without trace. Takes a few coats, though.

I just snapped a pic. It's hard to photograph black, the light disappears.
Top to bottom: untreated pine, pine, (tannic acid, eboniser, trad wax), Tas Oak, Camphor Laurel. (None of these usually ebonise. It is worth getting some tannic acid.)

Thanks for all suggestions. In the latest FWW, a contributor has had good results with leather dye. Might be worth a try.

This is pretty impressive, Humphrey,well done I suspect the home brewing mob are going to get a few orders. Can you see the grain of the timbers?

Alex, will be interesting to see the effects of leather dye too. I think Humphrey was talking about it in an earlier post too ... great minds, eh? My India Ink is still in transit from the UK

Originally Posted by JillB

This is pretty impressive, Humphrey,well done I suspect the home brewing mob are going to get a few orders. Can you see the grain of the timbers?

I was thinking that very thing - the folks at Country Brewer will be wondering why there's suddenly such a need for so much tannic acid.
The grain shows through nicely.

Alex, will be interesting to see the effects of leather dye too. I think Humphrey was talking about it in an earlier post too ... great minds, eh? My India Ink is still in transit from the UK

Alex, I started tests with the Raven Oil, (leather dye), last night. As a stand-alone timber dye, it works very well.
My next test is for a blacker-than-black finish, by treating with tannic acid, ebonising, then applying Raven Oil after drying.

Jill, I'm looking forward to hearing your results from the India Ink. It's reputed to work well. I thought about ordering some yesterday, but the cost of a large container was off-putting. Might still get some, but not right now.

I still haven't tested the Dylon Velvet Black fabric dye, but I suspect that I don't need to now. Also still got the potassium permanganate sitting here. I'll have to give it a spin when I get a chance. Should produce a nice brown.

I'll post some pics of the Raven Oil tests later.

Our local home brewer in Townsville is out of stock already, slightly cheaper at $2.95 for 25 gm