There are several different ways to make ink, but the most common was to use berry juice. Children can make their own ink and get an appreciation for what their ancestors had to go through to be able to write letters and other documents. It will also help the children understand how some inks are made.
Make Ink From Berries
Buy some fresh raspberries (1 cup) or thaw out a 12 oz. package of frozen raspberries.
Get out a glass or metal bowl. Don't use plastic because the berry juice will stain it permanently. Put your strainer over the bowl. Put the raspberries in the strainer and squeeze all of the juice out, leaving the pulp in the strainer.
Add 1/2 teaspoon of vinegar. If you have ever dyed Easter eggs you know that vinegar helps keep the color in the dye you mixed with water. The same concept applies here. Mix together the berry juice and the vinegar.
Add 1/2 teaspoon of salt. Salt is used as a preservative. If you are going to use your ink more than one day you will need the salt to keep it preserved. Mix together all 3 ingredients.
Pour your ink in to a baby food jar and close the lid. Your ink is now ready for you whenever you need it.
Make Invisible Ink
Combine 5 tablespoons of water with 5 tablespoons of baking soda in a mixing bowl. Mix thoroughly.
Dip a paintbrush in to your water and baking soda mixture and write a message on a piece of paper.
Pour some grape juice over your picture and your message will be revealed.