Goldenrod paper is a special paper that drips blood! Really, it’s not blood, just a safe red liquid that resembles it. The paper contains a pH indicator that turns red in the presence of a base. You can use it to demonstrate pH indicators or for a spooky Halloween science project. If you like, you can write a bloody secret message or create a bloody hand print.
Bleeding Paper Materials
This project uses a special paper, called color-changing goldenrod paper. As you might guess, it gets its name from its color. The paper is available at Amazon and some education and craft stores. Be sure to use the color change goldenrod paper and not just any yellowish paper. The color change results from alkaline conditions, which can be obtained using ammonia, baking soda, laundry detergent, washing soda, or soapy water. Ammonia mixed with water works extremely well, but younger researchers may wish to use baking soda in water, since it is very safe.
- color-changing goldenrod paper
- household ammonia or baking soda
- cotton swabs or cotton balls
- wax crayon or white candle
Bloody Hand Print
- Dip your hand in a mixture of household ammonia and water or baking soda and water.
- Slap your hand onto a sheet of goldenrod paper. See the bloody hand print? If your hand was wet enough, the paper will appear to bleed, too.
Bloody Hidden Message
- Use a wax crayon or piece of white candle to write a message on the goldenrod paper. The message should appear invisible on the paper.
- Reveal the message (in ‘blood’) by wiping the paper with a cotton ball dipped in ammonia.
How It Works
Goldenrod paper contains a pH indicator that changes the paper from golden to red in the presence of a base, such as ammonia. Notice the red color fades after a while. This is because carbon dioxide in the air makes the liquid more acidic. You can play with stronger bases, such as washing soda, which will not change color in air. For a stronger base, you can counteract the pH using a common household acid, such as lemon juice or vinegar.