It's easy-peasy!!! If you have a walnut tree or know someone who has, you can make your own walnut ink. It's fabulous for ageing paper or cardstock. I've shown you what it looks like on plain white paper when it's just dipped in and dried.First get your old dry walnuts and pry off the black outer skin. Some of it will stick and some will come off easy, just get as much off as you can. Using a blunt object eg a pestle or the end of a wooden spoon or rolling pin, crush the skins up into smaller bits.
Cover the lot with water and bring to the boil. Simmer until the ink is as strong as possible, I did mine for an hour or so. Don't let it dry out!Strain the liquid, add some vinegar to preserve it, I used about 1/4 cup for mine but it depends on your quantities. It won't keep forever but you could freeze it in small lots for later use. Now eat your walnuts!!!!!