The Art of Dyeing and Colorfastness of Dyed Fabric

For thousands of years, dyes have been used to improve the appearance of things. Our world is filled with beautiful objects that come in all colors of the rainbow.

In this project, you will learn about different methods of preparing material that is to be dyed. You will also determine the colorfastness of dyed fabric and examine the oxidation resulting from bleach and sunlight.

Getting Started

Purpose: To determine whether vinegar is necessary for dyeing eggshells.

Materials

• I-pint (500-ml) jar
• distilled water
• 1-teaspoon (5-ml) measuring spoon
• blue food coloring
• 2 cups
• marking pen
• masking tape
• white vinegar (5%)
• large spoon
• 2 eggs (hard-boiled)
• paper towel

Procedure

1. Fill the jar half full with distilled water.
2. Add 2 teaspoons (10 ml) of food coloring to the water and stir.
3. Pour half of the colored water into one cup and half into the other.
4. With the marking pen, write "With Vinegar" on a piece of masking tape and tape this label to one cup.
5. Add 1 teaspoon (5 ml) of vinegar to this cup and stir.
6. Label the other cup "Without Vinegar."
7. Use the large spoon to place one egg in each of the cups (see Figure 17.1).
8. Allow the eggs to remain undisturbed for two minutes.
9. Remove the eggs and place them on a paper towel. Do not dry the eggs with the towel; allow them to air dry.
10. Observe the color of each egg.

Results

The egg soaked in the dye solution containing vinegar is a darker blue than the egg soaked in the dye solution without vinegar.

Why?

To dye an object, the molecules of dye must stick to the surface of the object. In this experiment, the dye is attracted to the eggshell due to a difference between the electrical charge of the molecules of dye and the electrical charge of the molecules on the outside of the eggshell. Vinegar (acetic acid and water) reacts with the layer of protein molecules covering the surface of the eggshell so that the surface becomes positively charged and attracts the negatively charged dye molecules. Some of the dye molecules simply become lodged in crevices in the eggshell; thus, the egg in the solution without vinegar has some color.

Try New Approaches

1. Is the intensity of the color of the egg affected by the concentration of vinegar in the dye solution? Repeat the experiment two times, first adding 2 teaspoons (10 ml) of vinegar to the colored water, and then adding ¹/₂ teaspoon (2.5 ml) of vinegar.
2. Does the temperature of the solution affect the results? Repeat the original experiment two times, first adding ice to the colored water to chill it, and then using hot tap water.
3. Does the color of the dye affect the results? Repeat the original experiment using other food colorings. Science Fair Hint: Display color photographs of each egg along with descriptions of each procedure.

Design Your Own Experiment

1. Can the surface under the cuticle, the thin protein layer covering the eggshell, be dyed? Use a nail file to rub back and forth across one spot on the surface of a hard-boiled egg until the outer layer of the shell is removed. Fill a cup half full with distilled water. Add 1 teaspoon (5 ml) of red food coloring and 1 teaspoon (5 ml) of vinegar and stir. Place the egg in the red vinegar solution. Remove the egg after two minutes and observe the coloring on and around the area rubbed with the file.
2. Two methods are commonly used to dye cloth. One is direct dyeing (dye is affixed directly to the cloth), and the other is indirect dyeing (dye unites with a mordant, a substance affixed to the surface of the cloth). Note: Before demonstrating these two dyeing methods, remove the sizing if the material is new (material used to fill the pores of fibers of fabric) from two 12-×-12-inches (30-×-30-cm) pieces of white cotton cloth. Pour 1 cup (250 ml) of water into a saucepan. Add 1 tablespoon (15 ml) of sodium carbonate (washing soda) and stir. Put the cloth pieces in the solution and bring to a boil. Boil for two minutes. Allow the solution to cool. Remove the cloth pieces and rinse in water. Prepare a commercial cloth dye by following the directions on the package. Use the following instructions to dye the cloth pieces.

   

   1. Direct dyeing can be done by pouring 1 cup (250 ml) of the dye solution into a bowl. Put one of the cloth pieces in the bowl and stir for two minutes. Remove the cloth and rinse with water. Allow the cloth to dry.
   2. Indirect dyeing requires further preparation of the cloth. First, boil the cloth for two minutes in a solution made of 1 cup (250 ml) of water and 1 tablespoon (15 ml) of Epsom salts. After cooling, rinse the cloth with water and soak the cloth in household ammonia for one minute. CAUTION: Ammonia is a poison. It and its fumes can damage skin and mucous membranes of nose, mouth, and eyes. Remove the cloth and rinse with water. Wring out any excess water. Soak the cloth in 1 cup (250 ml) of dye solution for two minutes. Remove the cloth and rinse with water. Allow the cloth to dry.
3.  

   

   Demonstrate the fading effect of sunlight by folding a piece of red construction paper back and forth into accordion like pleats (see Figure 17.2). Place the folded paper in a sunny window for four to five days. Note: Do not change the position of the paper. Then, unfold the paper and observe the color of the pleats.

   Demonstrate the bleaching effect by adding drops of bleach to a variety of fabric samples including cotton, nylon, rayon, acrylic, and wool that are all of the same color (the colors may not be exact, but make an effort to get them as close as possible). Cut each fabric sample into two 4-inch (1O-cm) squares. Place one square of each fabric on a plastic tray and drop three drops of bleach in the center of each piece of fabric. Make observations every ten minutes for one hour. Compare the color of the bleached and unbleached samples. Compare the colorfastness of the different types of fabrics. Rinse the bleached samples with water. Use them on a project display to represent the results (see Figure 17.3).

   1. Colorfastness is the resistance a dye has to fading. The oxidation (combining with oxygen) of dye molecules results in molecules that are colorless or that have very little color. Ultraviolet light from the sun makes oxygen molecules in the air more reactive; thus, colored materials placed in the sun fade more quickly.
   2. Bleach contains sodium hypochlorite, a chemical that contains chlorine and oxygen, among other elements. Chlorine has a strong affinity for hydrogen. When bleach comes into contact with a dye containing hydrogen, the hydrogen is removed by the chlorine and oxygen is left in its place. The oxide formed is white or less colored. CAUTION: Avoid contact with bleach. It will irritate eyes, skin, and mucous membranes. Do not mix it with acids, ammonia, or other household chemicals because toxic gas may form.

Get the Facts

1. As long ago as 3000 B.C., dyes extracted from plants were used in China and the Middle East to color textiles. Find out more about natural dyes. Make a list of common plants that can be used to produce specific colors. Discover methods of extracting the dye from plants. You could color pieces of cloth with your dyes and display them.
2. In 1856, the English chemist, William H. Perkin, was trying to produce quinine from coal tar, when he discovered mauve-purple dye. He later discovered a second synthetic dye, magenta. Find out more about synthetic dyes. What contribution did Karl Grabe and Karl Liebermann make to the dye industry? What effect did their discovery have on the profitable cultivation of madder plants in France, Holland, Italy, and Turkey?

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