While I was at Zea Mays Printmaking for professional development I went camping. Specifically at the DAR Campground. My camp spot was ringed by a whole variety of trees but mainly by several tall straight oaks. During my third night there I could hear acorns dropping. I had looked for interesting rocks but neither my camp site or any of the trails I visited had anything that would work for making paint.

I decided to get acorn caps. Acorn caps hold a lot of tannins and have been using for dying and ink making for a very long time. They are often used as a source of tannins for gall based inks.

In my case I want to make a jug of acorn cap ink with and without iron.

I gathered roughly a pound of acorn caps- just the caps and no nuts. I put these into a black doggie doo bag and tied it shut. This stayed in my car for a few days. My thinking around this is that the heat would kill off any insects in the caps. I then left it in my studio for another few weeks.

The first step is to wash all dirt and insects away from the caps. This is easily done in a colander. It is important to NOT soak the caps lest some of the tannins soak away. I used cool water and agitation to remove all dirt and debris. I then spread my caps out in the sun to allow them to dry. 

After my caps were dry I started to break them up by hand. Many caps were very hard. I ended up putting the caps into a zipper bag and stomping on them to get more of the caps broken up. Once the caps were broken into smaller pieces I put some of them through am old hand crank coffee grinder. This worked well except for when it got jammed. I probably ground a third of my caps.

If I decide to make this again I will grind more of the caps. The ground caps leeched out the tannins substantially faster and more easily than the whole or just crushed caps. The coffee grinder was set to French Press grind size. In this instance a whirly grinder might be a better choice.

I used about 1.5l (6 ish cups of water) to cover the caps. I used a pan that will not be used with anything but ink making supplies. I brought this to a boil and then let it cool off then a boil again. I probably boiled and cooled the caps 4 times. 

When cool enough to handle I strained the caps through a kitchen towel. The caps held at least half of the water in them. I squeezed them out the best I could but not much additional squeezed out.

This was returned to a cleaned out pot and brought to a boil and then simmered until it was reduced to about 1/3rd of a cup. Through out the boil there are visual changes in viscosity- the mix goes from very thin to thicker and at the end it is not thick but it coats the bottom of the pan. This initial steeping resulted in a lovely warm golden tan that I am in love with. 

I added a small amount of gum arabic to help bind it to the page when used for sketching. I suspect one could also use some casein based binder. There are a lot of binders out there but I had gum arabic. It would be super traditional if I harvested some peach or plum gum and used it in the same way. I added maybe a teaspoon, I should have measured better. The amount of gum is enough that after 24 hours the ink coats the sides of the jar I’m using for storage.

For storage you want an airtight jar or bottle. I’m using a vinegar cruet I inherited from my grandma, she’d hate that I’m using it for a practical purpose and not for decoration. That said I wrapped the stopped with some paraffin film used for sealing bottles in the lab. This creates a really nice air and watertight seal. I wish I could remember who I learned this from- it was during an ink exchange a long time ago!

The ink does darken on the page with time. I read one account that claims it darkens more over a month, but I suspect that is for the iron blended version. 

Some things I noticed, after the initial strain I didn’t notice all that much in particulates, I’m wondering if the tannins gather together in heat? Did I extract some starches? Did I scorch it?

This smells amazing. The odor reminds me of walking through the woods on a hot August day and of a strong cup of tea. It’s got a vague hint of the Caran d’Ache SwissWood pencils but pleasant.* Sadly this odor is covered up by the essential oils I use for preservation.

I’m really glad I did this project outside, I got distracted once and boiled the batch over quite a bit. I lost a good amount of the extract. I’m a little annoyed by this.

​I have noticed that many people do a very long and hands off extraction technique- boil the water once and then let it steep for a month or more. At that point you strain and boil it down. I don’t have the attention span to do that and not let it dry out or get moldy so I’m using relatively fast extraction methods.

I’ll have more observations after the next batch.

Next up is gathering some black walnuts and making some walnut ink.

I would not using this in a fountain pen or nice brush pen, I’m going to put a few milliliters into a cheapie brush pen and see how it does, but I expect clogging. We’ll see.

*I hate the smell of the swisswood pencil.