From Seed to Seed:
Activity 39: Getting the Color Out
Associated Lesson Topics:
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?
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.
Many common plants can be used for dyeing. Here are some suggestions.
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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