Making Iron Gall Ink

Many thanks to Sara Charles, an editor at the Institute of Historical Research and researcher of medieval manuscripts, for this guest post, which is based on a Twitter thread originally published here



I’m not artistic, crafty or very in tune with nature, but as someone who researches medieval manuscripts, I wanted to experience the process. And surprisingly (or unsurprisingly, give their nature), so did my cat. There is some open ground behind my house, so I went for a forage for some oak galls. I didn’t really know if I would be able to recognise what I was looking for, and it took me a while to find any. But, once I had spotted one, I got my eye in:




Based on my vast experience of one foraging trip, I found them much easier to spot on smaller, younger oak trees. This little one in particular had loads – I got about twelve from it. In less than an hour, I had collected this lot – 123 grams:




At first I was terrified that a wasp would emerge as I was separating a gall from a branch, or I would get swarmed by angry wasp parents, but after a while it all felt lovely and I felt tuned-in to nature and the past. Although I did scream when a dragonfly flew near my face.



I loosely followed the recipe from Patricia Lovett’s book ‘Tools and Materials for Calligraphy’ (but there are plenty of other recipes – the Iron Gall Ink website is very useful ).

First, the fun part – smashing up the galls. I weighed out 80 grams:




I put them in a clear plastic bag rather than a newspaper, mainly because I wanted to see what was happening. I was still a bit worried about baby wasps, but apparently this did not bother medievalists, they actually preferred the grub still inside:





So, after some cathartic smashing and freeing of small insects that crawled out (no grubs, just earwigs) in 5/10 minutes I had this bag of small chunks. I liked Patricia’s recipe because you didn’t have to grind them down into a powder. Then I poured them into a jam-jar:




Most recipes recommend rain water, but it’s been a long dry summer and I think our rainwater is probably more polluted than medieval rain, so I used distilled water (about 300ml). Gave it a quick stir with a lolly stick and then left it on a sunny windowsill for three days:




It went such a lovely deep brown. Next step was adding the ferrous sulphate (50 grams). Also known as copperas or green vitriol. I found this easily on Ebay. Apparently you can make your own with rusty nails, but I really wouldn’t recommend that




The video shows how instantaneous the colour change is. At this stage my cat decided to get involved. NB – now the mixture stains, so mind your fingers. And your cats:




We don’t want a repeat of this: Photo: Emir O. Filipović



The mixture went a really intense black. Almost blue-black. The cat was forbidden to go near the windowsill. The lolly stick was stained beyond redemption:




Let’s take a moment to stare into the abyss…



After a few more days, the next step was to grind up 25 grams of gum arabic into powder. Chloe was now fully onboard with the ink-making process:




The gum arabic was beautiful and sparkled like jewels. Chloe approved. Gum arabic thickens ink and enables to it adhere to the writing surface:




After I had ground it down to a powder, I added it to the mixture of oak galls and ferrous sulphate. Once again Chloe photobombed the video. Not sure that I could see that much difference in the mixture, but left again for a day on the windowsill:




Luna was sad she’d missed all the fun:



Last stage! (Thanks for sticking with me.) I strained the mixture through a muslin cloth using a funnel. More sensible people would probably use gloves for this part. I left it for a while to let gravity do its thing. Chloe stealthily checked my progress:




After about an hour I gave the muslin a final squeeze. I ended up with about 125ml of ink:




Time to test – and … success! The ink was a lovely black, and it seemed to flow nicely. I unashamedly used a quill pen I bought from Harry Potter world to write the labels. Calligraphers will probably be horrified:




So now I have lots of ink and some lovely gifts for my friends. The process took about a week, but most of that was standing time. It wasn’t too messy and no inky pawprints. (Although it was no coincidence I did this in the week my children were away…)




I wanted to do this to get a better understanding of the medieval process, and I really did. Its amazing that I’ve ended up with something I can use. And it was really easy. And – I have a surprising new respect for wasps.



Quality control from Chloe. She is happy to answer any ink-based queries.



Follow me on Twitter @sarajcharles for more experiments with manuscripts


  1. Thank you for posting this–I have always been curious about this process, and it was great to see it step by step. Enjoyed your kitty, too!

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