Fading Colors
In this exploration students read about a set of paintings that were damaged by sunlight. Then they conduct some experiments to determine what sort of chemical"Paints" are most affected by light.
Read the story here. Then do the experiments and reread the story. Based on your experiences do you think the story is accurate? Did the sun really ruin the paintings? Write about your experiences and your conclusions in your journal.
Materials Required:
• Different paints (water color, food color, construction paper)
• Test papers
• Small objects that will provide shade for some of the test paper
• A sunny day!
• Journal
Procedure:
There are many ways to do this exploration. Here are three ways of exploring the effects of sun on dyes and paints:
Option 1:
1. Find some school construction paper. This is a colored, relatively cheap recycled paper with a rough texture..
2. Cut the paper in quarters and place an object atop each section of the paper.
3. Leave it in the sun for a few hours.
4. Observe the results.
Option 2:
1. If you have watercolors, paint a square of any kind of white paper. Darker colors like blue and purple are best.
2. After the paint is dry, place your object on the paper in the sun.
3. You may need to leave it in the sun all day!
4. Observe the results.
Option 3:
1. Prepare a shallow dish of food coloring and water.
2. Cut a square out of a paper towel.
3. Soak the paper towel in the food color bath. (Food coloring will stain your clothes and fingers, so be careful!)
4. After the paper towel is dried, place an object atop the paper and place it in the sun.
5. Observe it after a an hour, after two hours, and more hours.
Questions:
1. What do you think the sun does to the color? Where does the color go?
2. How could you protect a piece of artwork from the sun?
Discussion
The sun's rays fade colors. What does that mean? First, it is good to know what makes up color. In nature, different colors come from different chemicals that are produced by plants and animals and from mineral colors that come from various elements and compounds. Sunlight has powerful rays of different wave lengths that hit these molecules. The energy in the rays can actually bounce the atoms around and change the molecule. When we see "fading" it is actually a chemical reaction in the pigment caused by the rays of the sun.
One interesting thing about some animals and especially birds is that their colors do not fade in the sun! Why? In the case of mammals they are always replacing their hair, so new hair grows out in the right color. In birds, the color is often caused by a refection of light off of the way the feathers are folded. Birds' colors can't fade! Plants keep producing new pigments until the flower or leaf dies--then it fades!