Blueberry pickers experience firsthand the staining power of blueberry juice on clothes and fingers. As it turns out, this same intensely-colored liquid also makes an excellent ink for writing in a pinch. According to Scholastic.com, soldiers took advantage of this feature of blueberry juice for writing letters home during a Civil War-era ink shortage. Today, a sharpened feather or a quill pen dipped into homemade blueberry ink works as well as an ink pen to write your thoughts on any regular paper.
Place the blueberries into the strainer, then set or hold the strainer over the bowl. Mash the berries into the side and bottom of the strainer to release the blueberry juice.
Continue mashing until you get all the juice out of the berries. Leave the strainer over the bowl to drain the juice into the bowl.
Remove the strainer and mashed blueberries, then add 1/2 tsp. each of vinegar and salt. Stir the blueberry ink with a teaspoon until all the ingredients are blended.
Add 1 tsp. water to thin the ink if it is too thick, then stir the mixture again. Pour the blueberry ink into a covered plastic container until ready to use.
Make sure the bowl is the right size to fit the strainer over the bowl for easier mashing.