I thought I'd share a couple of my favorite oak gall ink formulas. The first one is from the Renaissance period and it creates the granulating ink you see above.
1500s formula
1oz oak galls
12oz water
soak for 6+ days (I smashed the oak galls in a pestle and mortar before adding to water)
boil mixture to reduce to 8oz
strain out the oak galls and add the following -
1/4oz ferrous sulphate (iron sulfate)
1/2oz gum arabic
1/2oz vinegar
mix well and leave to cool
If you prefer a formula with no granulation then the following recipe is for you
oak gall & red wine
240ml red wine
1oz oak galls
crush oak galls
soak in wine
heat and steep
strain and add -
1/2oz ferrous sulphate (iron sulfate)
3/4oz gum arabic
mix well and leave to cool
this creates quite a thick ink which is a pleasure to use for both writing and drawing.
Oak galls can be dried out and used again and again, with each use bare in mind that you will need to soak and heat for longer periods.
I found the best time to look for oak galls is during winter when there are no leaves on the trees. Look for young oak trees or trees that have been cut back so the branches are at an easily accessible height.
If you're not having much luck you'll find people selling oak galls on both eBay and etsy.