Abstract : Do you ever wonder how markers are made? Where do all of those colors come from? Many of the colorful dyes we use come from plant pigments. Pigments are what make the world around us so colorful. How do chemists turn those natural plant pigments into art supplies? In this science project, become a chemist and make your own marker out of a drinking straw and homemade plant dye!
Objective : In this science project, you will extract plant pigment and use paper chromatography to compare the pigments to color molecules in water-soluble markers.
Introduction : Many modern products are made using bright colors. The many colors come from colored molecules that are mixed into the material used to make the product. There are many examples, including food, plastics, art supplies, and fabric. Some colored molecules are synthetic, like the famous Yellow #5, found in many candies and food products. Others are made from natural pigments found in plants. A pigment is a protein molecule from a plant that reflects a certain color of light from the sun. This color is reflected and seen by your eye, which tells your brain that you are seeing a certain color. Sometimes plants contain many pigments that mix together, but your eyes see the pigments as only one color. Oftentimes, the colors that we see in nature or in manufactured products are mixtures of different-colored molecules. Even though our eye sees the result as one color, each of the separate color molecules stays true to its own color in the mixture. One way to see this is to find a way to separate out the individual color molecules from the mixture, to reveal their unique colors.
Chromatography is the way chemists separate the components of a mixture into individual molecules. During chromatography, the components of a mixture start out in the same place, but are separated by their chemical properties. The type of paper chromatography you will use separates pigment molecules based on their size, because small molecules will move faster through the paper than the larger molecules. Imagine that you and your parents are running through a crowded park. You will probably get to the other side faster because you are smaller than your parents are. In this science project, you will learn how to extract pigment molecules from plants, and compare them to synthetic color molecules using paper chromatography. Will the natural and synthetic dyes have the same or different color components? Can you use your homemade dye to make your own markers?
Terms, Concepts, and Questions to Start Background Research : To do this science project, you should know what the following terms mean. Have an adult help you search the Internet or take you to your local library to find out more : Pigment Chromatography Molecule Dye
Materials and Equipment : A colorful spice, tea, plant, fruit, or vegetable (good sources should be rich in color and include, but are not limited to: blueberries, cranberries, beets, yellow onion, red onion, turmeric, black tea, coffee). Note: Be sure you have enough to cover the bottom of a saucepan. Cutting board (if you need to chop your plant source into small pieces) Knife (if you need to chop your plant source into small pieces) Saucepan Stove Water Bowl Strainer (if using a plant source that does not dissolve in the water) Large glass jars (2), canning jars that are about 6 1/2-7 inches tall work well.
Lab filter paper (4 1-inch-wide strips that are 1-2 inches taller than your glass jars; you will use 2, but need extra to allow for mistakes); can be ordered from an online science supplier like Carolina item #712802. Note: Coffee filter paper will not work. For more information on which papers will and won't work, see our Paper Chromatography Resources guide. CarolinaPaper Chromatography Resources Drinking straws (2) Ruler Dropper, such as an eye dropper Water-soluble marker to match your dye color Lab notebook Cotton cording, 1/2-inch diameter; found at a fabric or hobby store Piece of string that is about 8 inches long Newspaper Small piece of clay Materials and Equipment :
Experimental Procedure : Pick out a plant source to extract your dye from. Make sure you have enough of the plant source to cover the bottom of a saucepan. If your plant source is large, you will need to finely chop it into little pieces using your knife and cutting board. Have an adult help you with this step. If the color is concentrated into the skin, you might want to peel the skin off and use only the skin. Add the plant material to your saucepan and add just enough water to cover the plant source. If you selected tea or a spice, add enough water so that it is floating or mixed into the liquid and not just absorbing the water or turning into a paste. Bring the mixture to a boil and simmer covered on the stove for approximately 10–15 minutes. The pigment from the plant material will slowly begin to color the water in your saucepan.
Figure : Figure 1. The diagram above shows how each glass jar should be set up. Make sure that each dye you test is in its own jar and that all dye spots are 2 inches from the bottom of the filter paper.
–Safety Notes: Do not leave the plant-water mixture unattended on the stove. Remain nearby to make sure it does not burn. It is also a good idea to do this in a well-ventilated area, or with the stove top fan running, in case the cooking plants release bad- smelling fumes. If the color of your water is too faint, you may want to concentrate the color by removing the lid of the saucepan and continue boiling until enough liquid has evaporated, leaving behind a darker liquid. When the color of the water is rich in color, remove the saucepan from the heat and allow the dye to cool. If there are pieces of material in your saucepan, separate the dye into another bowl using a strainer and set the bowl of dye aside. If your plant source dissolved, just pour the liquid into a bowl and set it aside. Now that you have your homemade dye, you will want to compare it to a dye from a similar color of water-soluble marker. Cut two strips of filter paper that are each 1 inch wide and 1-2 inches taller than your glass jars. Poke a hole in the top of each filter strip, and push a straw through the hole.
Use the straws to hang your filter strips into the two glass jars, so that just the bottom part of the filter strips touch the bottom of the jars. There should be one strip in each jar. Trim the strips, if necessary. Now remove your filter strips and pour about 1 inch of water into the bottom of each jar. You can use your ruler to measure. Using a dropper, at the bottom of your first filter strip, carefully squeeze out a small drop of dye 2 inches from the bottom of the strip. The drop size should be about the size of a pencil eraser. If your dropper puts out a drop that is much bigger than that, you will need to repeat steps 8-12 with a new strip. Allow the spot to dry. If after drying, the spot is too faint, you will need to repeat steps 8-12 with a new strip to make your spot darker. Now, using the water-soluble marker that is the same color as your dye, take your second filter strip and make a dot the size of a pencil eraser that is 2 inches from the bottom. When the spots are dry on both strips, hang the strips in your chromatography chamber glass jars. The level of the water should be below the spots of color, and the spots of color should both be 2 inches above the bottom of the jar. The setup for each glass jar should look similar to the diagram in Figure above.
Now watch as the water moves up the filter strip. What happens? When the water reaches the top of your strip and you can see that the colors have separated, remove your strips from the jar and allow the strips to dry. Lay your strips side by side to compare the color components. Make a drawing of each strip in your lab notebook. What do you notice? Make a list of similarities and differences. Now you are ready to make your dye into a marker. Cut a piece of 1/2-inch-diameter cotton cording that is 1/2 an inch longer than your straw. Tie a piece of string to one end of the cotton cording to help you pull it through the straw later.
Lay your piece of cording over the edge of the bowl of dye so that only half of the piece is soaking in the dye. You should soak the end that does not have the string attached to it. Soak the cording for 5 minutes. Lay down some newspaper so you do not spill dye on your work surface. Now slowly and carefully thread the string through the straw and pull your wet piece of cording through the drinking straw. Watch out, this will be messy! Plug the end of the straw with the string coming out with a small piece of clay. Let the cotton cording hang out of the other end of the straw, this will be the end you will use to write with. Now you are ready to write a message or draw a picture with your new homemade marker!
Variations : Try other sources of material to get new and different colors of dye. Can you try to make yourself a complete set of homemade markers? Which materials made the best colors? Another fun chromatography project is to use Kool-Aid® as a source of pigment. Conduct an experiment using your favorite flavors of Kool-Aid. Do some of the different flavors use some of the same coloring agents? Which flavors contain mixtures of different colors? Some plant pigments change color when they are mixed with an acid (like vinegar) or a base (like baking soda). Conduct an experiment on different plant dyes to see which ones have this amazing color-changing ability!
Bibliography : This web site at Chemistry 4 Kids has a great tutorial on chemistry, matter properties, and mixtures. Go check it out: Rader, Andrew. (2005). Rader's Chem4Kids. Retrieved December 13, 2005 from http://www.chem4kids.com/files/matter_intro.html http://www.chem4kids.com/files/matter_intro.html Burch, Paula. (2005). All About Hand Dyeing: About Natural Dyes. Retrieved December 13, 2005 from http://www.pburch.net/dyeing/naturaldyes.shtml http://www.pburch.net/dyeing/naturaldyes.shtml Cobb, Vikki. (1972). Science Experiments You Can Eat. Harper Collins, New York, NY. Retrieved December 13, 2005 from http://www.vickicobb.com/scienceyoueat.html http://www.vickicobb.com/scienceyoueat.html