From Seed to Seed:
Plant Science for K-8 Educators

Activity 39: Getting the Color Out

Grades: K-8

Associated Lesson Topics:

• Ericaceae (heath) family; blueberry is a member
• Rosaceae (rose) family; blackberry, raspberry, and strawberry are members
• Contents of cells
• Pigments

National Standards:

• SCIENCE: Standard A, Standard C
• GEOGRAPHY: Standard 1
• HISTORY: Standard 1 (5-8)

Planting the Seed:

What color is your favorite shirt? How do you think that color was made? Can you think of any colors in the natural world that could be used to dye clothing?

Teacher Information:

Chlorophyll plays an important role in photosynthesis. This green pigment enables the plant to capture light energy from the sun and convert it into food for the plant. Colors produced by other pigments attract insects and other animal pollinators. In this activity, students will learn about the important role that pigments have played in human history. They will investigate the many plant parts that can be used to make dye (a great opportunity to review plant anatomy). And, by hypothesizing, changing variables, observing results, and drawing conclusions, students will experience the scientific inquiry process.

Anthropologists have found animal skins and cave paintings dating from as far back as 15,000 BC that were dyed with plant parts. They have also discovered textile remnants from 3500 BC with traces of blue dye from indigo. In addition to coloring fabric and yarn, plant dyes have been used as cosmetics, watercolors, and war paint. There are two famous examples of how the British have historically used natural dyes. Inhabitants of the British Isles stained their bodies blue with woad (a plant) before battle to make them appear more fierce. Woad is also the earliest known source of indigo, the dye used to produce denim blue jeans. In the second example, the "red coats" of the British army were dyed using the madder plant.

Dyes are classified according to the technique that is used to affix the dye to fabric. Dyes that need only to be dissolved in water before being applied to fabric are referred to as direct dyes. On the other hand, mordant dyes require the use of metallic salts (aluminum, iron, chrome, and tin), called mordants, in order to bind to fibers. Depending on the type of mordant used, the pigment will produce dyes of different colors. Finally, vat dyes are those that are insoluble and require the use of microorganisms or chemicals.

Necessary Materials:

• Plant material. Students can locate plant material for dyeing from several plant sources. They can collect them in the wild, purchase them from the grocery store, or grow them in the classroom or schoolyard garden. Consider designing and planting a dye garden! Generally, a 4-to-1 ratio of fresh plant material to dyeing fabric (by weight) is recommended. However, students should be encouraged to experiment with different ratios.

Many common plants can be used for dyeing. Here are some suggestions.

• Material to dye. Animal fibers provide many more active "sites" for dyes to bind to than plant fibers. Therefore, an animal fiber like natural wool yarn is easier to dye than cotton or linen.
• Stove or hot plate to heat water.
• Spoons.
• Pots. Ordinary kitchen pots will do. Send a note home or search tag sales.
• Sink.
• Aprons.
• Rubber gloves.
• Strainers.
• Place to dry fabric after dyeing.
• Optional mordant. We recommend the non-toxic mordant alum (potassium aluminum sulfate), which can be purchased from a pharmacy or craft supply store, and cream of tartar from a grocery store. This step is not necessary for classroom use. Even without using a mordant, the colors will outlast the school year!

Procedure:

• Prepare fabric by washing with soap to remove dirt and oils that could interfere with dyeing.
• If you plan to use a mordant, pretreat the fabric or yarn. Measure 3/4 teaspoon alum and 1/4 teaspoon cream of tartar for each quart of water in your dye bath. Note: It is better to use too little mordant than too much. Dissolve this in 1 cup of hot water, then add it to a pot of water (1 quart of water per ounce of fabric). Wet the fabric to ensure penetration, then add it to the mordant solution. Simmer for 1 hour. Remove the pot from heat, then cool and rinse the fabric before adding it to the dye bath.
• Shred plant materials to expose more surface area.
• Cover the plant material with water in pot.
• Simmer for approximately 1 hour until the plant material appears bleached and the water is colored.
• Strain.
• Add fabric or yarn to dye bath and allow it to simmer for 30 minutes to 1 hour, turning the material gently.
• Rinse dyed material with progressively cooler water and hang it to dry.

Harvesting the Crop...

After the students have tried their hand at dyeing, have them experiment. Divide the class into groups of four or five. Each group should come up with a plant that they think can be used for dyeing fabric. Which plant part should be used? What color do you predict the dye will be? Why? What technique will you use to extract the pigments from the plant part? A fun way to present this to the students is to ask them what their favorite color is and then ask them to come up with a plant that they think can produce that color dye. Since not all colorful plant parts can be used successfully for dyeing, the outcome of this experimenting is uncertain. This process, therefore, mirrors the uncertainty faced by scientists involved in scientific inquiry. Students can also experiment with 1) the proportion of plant material to water or fabric used, 2) the freshness of the plant material, 3) how finely the plant material is shredded, 4) how long the fabric is left in the dye bath, and 5) the material that the pot is made of. Make sure they change only one variable at a time.

Since there is such a long history to natural dying, this exercise also presents a wonderful opportunity to study different cultures (e.g., Navaho) or different periods in history (e.g., Colonial America or the Middle Ages). Students can research the ways that dyes have been used and the different procedures followed. They can mimic these procedures in the classroom and compare them to the procedure they themselves tried first. Which procedure was more efficient? Which produced better colors?

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