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It's like alchemy.
There's something a little magical about ebonising Oak with this iron and vinegar wash. The reaction is so quick: brown liquid to black surface in seconds. And it is a reaction (with the tannic acid in the wood), not a simple stain. No doubt one of you can explain the chemistry!
I don't mention it in the lesson but you should finely strain the mixture to remove any iron particles before using. You can leave the mixture in the jar for ages, in which case the iron will disappear completey. The colour that results will vary with the Oak, between species and between wood from the same species. Often, as here, the resulting colour is blue-black rather than coal-black. Oiling makes the wood go even darker.
(Trivia: Did you know the Oak galls were used in earlier times to make ink?)
| 31 March 2017 09:27
I've just been further exploring the section on finishes, and I wonder if a liming wax might work for the light parts of a magpie, and this ebonising finish elsewhere.. I'll post a picture in the members' if I ever find the answer and complete the carving!
| 30 March 2017 07:29
Chris - please feel free to use the idea if you like, I'm sure you'd make it work really well! I never realised there was so much room for experimentation with finishes, and I look forward to trying a few things out on scrap wood.
| 29 March 2017 16:54
Russell - I've found lightening oak a bit disappointing in that bleaching seems to produce a sort of jaundice looking yellow, rather than white. I've been much more successful bleaching lighter woods. It might be that I needed to repeat the bleach several times and I'd encourage you to experiment on scrap wood.
As an aside, it's a great idea for a magpie. My surname 'Pye' comes from the old French for a magpie (with the 'pie' or 'pye' being the bird and "Maggy' the pet name, like Robin - Redbreast - or Jack Daw). It's a bird I'm very fond of but I've always avoided carving it because of that very black and whiteness. I never thought of ebonising and bleaching!
| 29 March 2017 09:22
This is incredibly interesting - I have a carving in mind, in oak, of a magpie, and I think this colour would be perfect! I'd love to experiment with other metals and woods as suggested in the comment below.
Chris, do you know of any similar methods for lightening the colour of woods like oak? Maybe bleaching somehow? This would be useful for the white parts of the magpie,rather than painting over the lovely grain..
| 29 June 2016 19:23
Alan - It was definitely white (clear) vinegar, not too sure whether it said 'distilled' on the bottle. Any vinegar (acetic acid) should react with iron, even the stuff you might sprinkle on your fish and chips. I wonder if you have steel wool that's been coated in something to prevent it oxidising in the air? You just need the cheapest possible.
| 29 June 2016 17:38
Hi Chris, could you tell me please if distilled white vinegar is the same as the vinegar you used as it has not reacted with the steel wool for me?
| 01 December 2015 16:41
Robert - Yes, I just dumped the wire wool in the jar too, covering it with vinegar. It did take a few days to start darkening, rather than hours. I think some wire wool has an oily coating to preserve shelf-life, making it slower to react. And, yes, if you pierce through you'll get a double helix. It's not easy to do neatly; it's the back of the bines, which now look like ropes, that are tricky to clean up well and of course the workpiece becomes springy and rather fragile as you have shortish grain. If you taper the starting cylinder but keep the pitch the same (ie stepping-off the same distance along the length), the effect is that the spiral lengthens as the cylinder gets narrower. I don't like how this looks, so I would incrementally shorten the stepping-off as the I move along to the narrower end, and then the effect is a uniform spiral even though the cylinder has become more cone-like. I hope that makes sense. Best thing is to draw is to draw it out and use your eye to get a sense of what change of pitch you'll need to keep the spiral spiralling uniformly.
| 01 December 2015 16:28
Tom - Thanks for those interesting comments on tannins. I think there's a PhD out there waiting for someone!
| 29 November 2015 22:13
Hello Chris,
A couple of questions:
I mixed the vinegar and steel wool (#0000) today. Your video indicated that it takes 1-2 weeks for the steel wool to dissolve and mixture to be ready to use. Even so, I was expecting at least some tiny bit of color change immediately, but after several hours the mixture is still clear. Was that your experience as well? Was it several days before you noticed any color change? I did not break up the steel-wool pad into tiny pieces, but just stuffed it in the bottom of the jar as you showed in the video.
Am I correct that if you were to pierce (completely remove them, essentially) the troughs between the bines, you would get a double-helix sort of arrangement? If that is the end result you wanted, would you lay it out the same way? How would your layout change if the piece you were working on was tapered lengthwise rather than a true cylinder? Thanks for all your videos and for taking the time to respond.
Robert
| 29 November 2015 12:52
As a chemist, I couldn't resist investigating the chemistry of the ebonization process. Tannins are a generic name for a diverse group of "polyphenols" found in wood. Under various conditions they are known to form pigments. Two key mechanisms for forming such pigments include oxidation and metal chelation. It is likely that the color from ebonization occurs through both mechanisms, as the reaction of iron and vinegar probably forms ferrous acetate, a mild oxidizing agent, and tannins are known to chelate readily with iron to form pigments. If the chelated iron pigments are a significant contributor to the color, it is possible that other metals (copper?) may form a different color. Also, since tannins are present in all woods (to different degrees), this process is not limited to oak, but the color will probably vary by species.
