Using “Exchequer Ink” to ebonize small detail parts
Sometimes ebonizing a small portion of a project can increase its overall impact dramatically. Consider the black cock-bead, small column capitals, or the feet on an Empire style piece. Simply adding the element of ebony to other species has much the same effect as triple underlining a critical word in a text. Ebonizing, uses domestic hardwood elements and allows the craftsman to mimic ebony (so well that many times experts have significant difficulty in determining the product’s authenticity). Walnut and cherry seem to be the best North American species for this purpose (due to their grain pattern), although it is not uncommon to see species like white oak and ash ebonized on a much larger scale, i.e. tables and chairs. Even simple cherry Shaker style turned knobs take on an uncommon elegance when they are blackened and the grain shows through.
The beauty of ebonizing is that it is a mordant dye (“bites into the surface”) that penetrates and is permanent. However, anyone who has done much ebonizing will tell you that it can be a messy job. Typically the surface to be treated is painted with a tannic acid “tea” and allowed to dry. The “tea” can be “brewed” from boiling oak bark and/or leaves, oak galls (little growths caused by wasps attacking the tree) or the purchase and mixture of a “bark tanning powder” used for tanning leather. Then iron is introduced to the surface as a liquid (vinegar and old iron nails is a favorite solution). The iron (acetate, I think – hey! I’m not a chemist) based liquid reacts with the tannic acid solution and, voila!, black, deep, beautiful, permanent black that allows the beauty of the grain to shine through.
For small detail parts this process can be a bit overwhelming. So I’ve opted for a simpler solution. Bring on the Exchequer Ink. What, exactly, is this “magic potion”? Well back in the days before computers, or comptomitors, or adding machines, accounts were kept “by hand”. And in the British Exchequer (Treasury), accounts were kept by a legion of scriveners who kept tally with dip pens (first goose quills followed by the modern steel dip pen) which carried an ink made from tannic acid (extracted from Aleppo Oak galls) and iron sulphate. This ink is most commonly known as classic iron-gall ink. Hello! Same stuff you use for ebonizing, except in a little bottle. Not great for a bookcase or a tavern table. But for a cockbead? Eureka! When Exchequer goes on it is a dull gray color. But after a few minutes, it “bites” the surface, oxidizes and turns a brilliant black. In fact, it can “bite” so aggressively that old documents will be found with holes where the “O”s should be. (That said, I’ve never found it necessary to neutralize the ink, or the standard ebonizing process, for that matter). I’ve used this mixture as my standard writing and drawing ink for more than twenty years. Some folks will add gum arabic or shellac to the mix to create a glossy finish. I brew my ink without the “gloss” factor and only add gum or shellac to the inks that I will use for writing. I’m not sure that either additive would be beneficial in ebonizing wood.
Here is a recipe for “British Exchequer Ink” from “Gaskell’s Guide to Writing, Pen-Flourishing, Lettering, Business Letter-Writing, Etc. 1884”
“Bruised galls (crushed Aleppo oak galls, still available from Kremer Pigments) 40 pounds; gum 10 pounds (as I said, this is optional if the fluid will be multi-purposed); green sulphate or iron (known today as Ferrous Sulphate), 9 pounds; soft water, 45 gallons. Macerate (let soak) for three weeks, with frequent agitation. Then strain and bottle. This ink will endure for ages and is one of the best inks ever produced.
My guess is that you don’t want 55 gallons of permanent black ink sitting around the house. So do the math and make up a small batch. I think you’ll find it very useful.
A thought in closing. Craftsmen of by-gone days usually had excellent handwriting. It was seen as a sign of intellect and good breeding. Of course it was the way you billed and got paid! I remember that my Grandfathers “day-books” bore script and drawings that could have rivaled the “Book of Kells” (alright maybe that’s a stretch, but he had damned fine handwriting). Perhaps our modern craft community could learn a “thing, or two”.