When you can't find acorns...

Oak Gall Ink

A few weeks ago, I’d headed off along the bridle path near my house to collect acorns. My intention was to collect a bagful so that I could plant them in pots with one of my groups with a view to germinating them and growing them on. Of the 38 oak trees that I examined, I found only 3 acorns. What I did find, however, were many oak galls; marble and knopper. Galls are woody growths that have been created where a particular type of gall wasp has laid their egg. Marble galls develop on a leaf bud and knopper galls on an acorn. The gall protects the growing larva. In September the larva is fully grown and emerges through a hole in the gall as a fully-grown gall wasp. Sometimes the gall falls off the tree, sometimes it hangs on tight for up to two years.

Well, if I couldn’t have acorns, I’d have to find something to do with galls…..

After some research I discovered that galls have been used in the production of ink for over a thousand years, due to their high levels of tannins. There seem to be a few different methods and varying recipes. The basis though, is this: galls are crushed, soaked (or heated or fermented), and then mixed with an iron solution – this turns the brown gall solution black. Sometimes gum arabic is added as a binder and to help the ink adhere to the writing surface. I discovered that gum arabic is made from the hardened sap of the acacia tree.

My interest tweaked, I embarked on some experimentation with my groups. Here is what we did…

1. Crush the galls. We put them in a cloth bag and whacked them with a mallet until the pieces were smaller. We then tried crushing them further with a pestle and mortar, but they were too hard. Back to the mallet.

2. We put them in a bowl and covered them with rainwater.

3. In another bowl, we put vinegar and rusty nails, bolts etc. This was to make the iron solution.

4. We left both for a week.

5. After a week, we strained the brown oak gall mixture through a coffee filter. This removed all the lumps and sediment.

6. We did the same with the iron solution.

7. A little gum arabic was dissolved in warm water and added to the gall solution.

8. Finally, we mixed the gall/gum arabic solution with the iron solution with an approximate ratio of 3:2.

The moment that we added the iron solution to the oak gall solution was magical – the liquids merged and turned a purply black, which seemed to darken further over the next few minutes. We got stuck in with using quill pens to try writing with it.