Part 1 of a  4 part series on Iron Black/Oak Gall Black Ink…

In which I go on and on about Oak Galls

Knopper galls and two little oak apples.

Oak gall and other tannine black inks go along way back and have popped up in religious books and legal documents stretching from Africa, China, Egypt and the Middle East, until eventually they and their parts made their way along the great Silk Road and wooed their way into every book of Hours and illuminated manuscript this side of Christendom.

There is a fantastic tradition coming out of 12th-14th century nunneries and monasteries of Europe in which each property sold, alongside many other home produced products, their black oak gall ink.

In the boarders or marginalia of manuscripts of the time, recipes are often found. It was in such a boarder, that this recipe was discovered and has been uploaded to the our current ‘holy book’,  the world wide web!

If you take a minute or two to search online for oak gall  or iron black ink, there will be a pleather of recipes coming at you. My favourite, I shall leave for my Charcoal & Other Beautiful Black Inks workshop. Here, however, is my second favourite!

There are no frills attached and yields very satisfying results.

Equal parts:

oak gall

rain water

Iron / vitriol / iron (ii) sulphate

Enough gum to bind and allow ink to flow.

First though, let me tell you about oak galls!

Oak galls are a realm of magic in and of themselves. You may be familiar with seeing them either as fallen debris from oak trees or still attached to the branches. Globally, there are many varieties. As for myself, I have only found two here in Ireland. The reason being, each gall is produced by a specific gall wasp…I know, and it gets better. In Spring the female gall wasp lays her eggs on the branch, by the stem where the leaf, acorn or branch is set to develop and off she goes. The entire life cycle of these wasps (some are tiny and not very waspish looking at all) evolves around the tree. Which in turn has a reaction to the egg and chemicals which have been injected into it, and responds by forming the gall over the single egg, instead of forming an acorn or leaf there.

When the larvae is ready to take on the outside world, they bore a hole out, and off they go. Leaving the tannin rich gall in their wake.

David Attenborough of course tells the story best as he does with most stories

When gathering galls, I always ensure that I do so in spring, and that there is a hole present. Some antiquated sources say that it is best to gather galls before the wild creature leaves its safe woody encasement. But to me, that sounds like poor nature management and poor practice of working alongside the wild things.

Plants utilise tannins for defensive purposes against weather conditions, bacterial and microbe infestations and for the bitter taste to make themselves less palatable to passing foraging creatures.

Oak galls are used for this method because of the high levels of tannic acid and so gallic acid present.

Following this logic, any plant source holding high yields of tannic acid will and do produce the same result. Alder cones, oak bark and oak chippings, birch bark.

The acids are very easy to leech out by either soaking or boiling hard in rain water. Either extraction method will work, but I find it more satisfying a process to allow them to seep, over time. And boiling only will result in a tannic acid rather than a gallic acid base, giving us a browner ink.

Tannins are subdivided into two groups. The one we are interested in is Gallic acid or  Gallotannic acid. It is this compound, when combined with iron that oxidises to the black we are after. But more on iron in Part 2.

With the boiling method I strain off the liquid, add the iron and reduce over a low heat. The reduction isn’t completely necessary, but again, better results are yielded if you do. Rain water is best, we are looking for a pH neutral water with as few minerals present as possible.

Now, here’s the sexy bit – fermentation through mould! This part makes me giddy with excitement.

By allowing a skim of mould growth to occur on the seeping crushed oak galls and water mixture, magic happens! Here’s how. The mould produces enzymes that gobble up the gallotannic acid and transform it to gallic acid. This gallic acid, upon reaction with our iron, results in a purer black ink

How cool and fabulous is that?!

After a month of this enzyme magic has been carrying on, I just scoop off the mould before adding iron and reducing. I’m also running with the theory that when mould forms at this stage, there is a marked depletion in any forming over the finished inks.

I also find I get better results from my galls after giving them a few serious blows with a stone or hammer (pop them into a pillow case first so you don’t have shrapnel flying about the place) and then running them through a coffee grinder. This takes a lot less time than it may sound like, and is well worth it.

Ground knopper galls, first smashed then sant through the grinder.

The Aleppo galls of Turkey are the best in the business. They have a tannic acid content of up to 90%. The British, and so I presume Irish galls have a content which is much much lower. But I still manage a nice ink from my local Knopper Galls (always brings Dire Straits to mind that name). It is possible to purchase the Aleppo Galls from Turkey if you wish to re-imagine the Silk Road!


Part 1 of a  4 part series on Iron Black/Oak Gall Black Ink…
Hello and welcome to my first stab at the auld blogging
Alder-Alnus glutinosa-Fearnóg