Litmus paper must turn some of the nicest colors I've ever seen. The following project will not only teach you how to salvage those little strips for use in an art project--it will teach you how to make your own litmus paper completely from scratch!
One cup red cabbage
Blender or Food Processor
Nylon knee high/piece of pantyhose (an old sock will also work)
Paper Strips (you'll want to use acid-free paper, such as scrapbooking or bookbinding paper)
Basting Brush or Paint Brush
Board or Piece of Cardboard
Step 1: Preparing Cabbage
1) Begin by chopping up the red cabbage into small bits. I used a kitchen knife and a cutting board. You may want to ask an adult for help.
Step 2: Blend the Cabbage
2) Place chopped cabbage in the blender of food processor with about a cup of water. Blend the cabbage until you can see purply juices beginning to emerge.
3) Stretch the nylon or sock to cover the opening of the blender/food processor. Pour the liquid through the nylon into the glass bowl (this prevents your pure cabbage juice from having floaties in it). If you don't have a nylon or sock to use, you can use a colander with small holes in it.
Step 3: Paint Your Strips
4) Place paper strips on top of a plastic trash bag or some old newspapers. Using the basing brush, brush a light coating of the purple juice onto your paper strips. The juice will turn blue as it dries.
Step 4: Test Household Materials
5) After the paper has dried, it will react to acids and bases. Use anything in your fridge to brush onto the paper to reveal a variety of colors. Some good things you might test are: pickle juice, lemon juice, baking soda mixed with a little water, or soap. Do NOT mix household chemicals together to paint onto strips.
Step 5: Weave the Strips
6) After paper has dried a second time, being weaving the strips together. I did this by taping down the rows of strips onto a piece of board, and then weaving each column strip one by one.