Red cabbage contains a soluble pigment molecule, which produces blue and red hues, making it perfect to determine the pH levels of common household items. If you don't have cabbage, use berries or cherries instead. TV crafter Jim "Figgy" Noonan explains how to perform your at-home testing.
Photography: Rob Tannenbaum
The Martha Stewart Show, January 2012
With a knife, finely chop cabbage and add two large handfuls to a blender.
Measure out 3 cups of very hot water and add to blender.
Blend cabbage and water into a slurry (adding more water if necessary) for about 1 minute.
Pour slurry through a strainer into a bowl, removing the pureed cabbage but saving the deep purple liquid.
Discard cabbage and clean strainer thoroughly. Line strainer with a paper towel or coffee filter and pour liquid through one more time to remove any remaining bits of cabbage. Allow purple liquid to cool before using.
With an eye dropper, add a number of drops of the purple cabbage juice indicator to each substance to be tested. Acids will turn reddish pink and bases will turn greenish blue.
Paper towel or coffee filter
Numerous glasses or cups
Substances to test (cream of tartar, soda water, aspirin, bleach, ammonia, baking soda, etc.)