As part of the London Plane Project I have experimented with ebonisation, a process of darkening or colouring a timber in a natural and respectful way – i.e. without the use of noxious chemicals or without covering the grain and figure of the wood in paint. An ebonising solution reacts with the tannins that naturally occur in the wood - acidity in the sap to be precise.
London Plane doesn't have a lot of tannin in it so it doesn’t turn jet black as with Oak or Ash but everything from a blue grey to an ashen green, either which works in perfect contrast with the un-ebonised lacewood.
Making the ebonising solution would appear straightforward – add steel to vinegar and leave for at least two weeks. But, as you might imagine, this is the least of it. That is merely the foundation. Through several rounds of experimentation, I have worked out the following about the ebonising solution;
The solution needs to be quite old, like craftspeople and wine, it picks up qualities through its maturity alone.
It needs a lot of rusty old pieces in it. At first I thought it may get redder in tone but no.
And it needs to be exposed to the air as much as possible. It will evaporate if left perfectly uncovered but try to give it lots of air daily.
Application. When using the solution prepare the timber with a tannin heavy liquid such as tea or red wine (the red wine bringing out a deeper blue - see image above). This draws out the tannin in the timber to make the reaction stronger - especially important for a timber like London Plane. Strong tea is perfect, the wine is powerful but does make the final colour redder. Rules;
Make sure the tea completely dries before applying the ebonising solution, the pale patches left on the wood is where the tea was still wet!
Cut back the timber after the tea has dried with some of those grey Mirka pads or something very fine.
Apply the solution consistently as if a stain or a paint – it will streak and blotch.
Wear double gloves. The stain on your hands are extreme.
Ebonisation has undoubtably added a new dimension to London Plane and the Lacewood in particular. Not only does it expanded the tonal possibilities of the finishes available but with the quarter-sawn Lacewood it accentuates the iridescence of the medullary rays while flattening the tone of the field behind them. I love it!