Making Walnut Ink from Black Walnut Hulls

For some reason, I was in a more experimental mood this fall than usual, and when the black walnuts started to fall, I suggested to my daughter that we make ink with them. Turns out that these nuts are a huge disposal problem for anyone with a black walnut tree in their yard and a friend collected a bag of them and dropped them off at my house for me!

The first step, after getting gloves on, was the hammer the hulls off of the nut shells inside. My friend shared that the nuts are edible, though small. We decided to leave the nuts for the squirrels, and they disappeared fast. The nuts that is.

Step-by-step Process in Making Walnut Ink

Breaking open the black walnut hulls to remove the nuts before making ink.

We used the book The Organic Artist by Nick Neddo as our guide. He said to use a stainless steel pot, add the hulls and just cover with water. So far, it’s like making soup. We worked outside, using a camping stove and a pot dedicated to art use.

We simmered the hulls for two hours. Three might have been better, for a darker color. We then used a wire scoop from the dollar store to scoop out the hulls. I added “hide glue” aka gelatin, and then filtered the liquid. This was a mistake! I should have filtered it and then added the thickener. The gelatin made it almost impossible to filter. To filter, I just poured it through a coffee filter. I poured it into a dark colored jar and added whole cloves to the jar to try to prevent mold.

Adding the Iron Water

A freshly set up jar of “iron water” to be. This is a rusty bit of metal in a jar of vinegar, shown with a jar of walnut ink in a dark bottle.

Finally, we tested the ink! And found it to be a bit light. The book said you could darken the ink by adding “iron water,” which you make by soaking some rusty bits in vinegar for a few days. Oxidation requires oxygen, so once a day, I would aerate the iron water by pouring it to another container and then back into the jar.

Once the iron water was ready, I added one table spoon per cup of ink, put the lid back on the jar and gave it a little swirl to mix. Here’s what our walnut ink looked like, before and after adding the iron water.

The word before was painted with our walnut ink before we added the iron water. The word after was painted after the addition of the iron water.

Why does the rusty water have this effect on the walnut ink? I don’t know the why of it, but I do know that walnut ink is a high tannin liquid. Tannins are what’s in fallen leaves that stains the sidewalk. Tannin baths can be used as a step in natural dyeing. In natural dyeing of fabric, adding rust to tannin baths makes the resulting fabric darker.

Overall, this was a fun and easy project! If you can still collect hulls but it’s too cold to stay outside with your camp stove, the various books on the subject say you can also make ink from dried hulls. So you could collect, dry, and cook it up in the future.

What will I use this ink for? I don’t have a use for it! I just wanted to try making it! My daughter will use it and I’ll jar some up to give to artist friends.

It’s just kind of cool to make your own art supplies, especially out of natural materials. If you want to try it, I definitely recommend the book The Organic Artist.