Making Radial Chromatography Creative Chromatography For Fun Flowers on Fabrics Robert Becker Kirkwood High School, St. Louis. MO 63122 John lhde West High School, Wausau, WI 54401 Kersti Cox and Jerry L. Sarquis Miami University, Oxford, OH 45056
Radial chromatography using isopropyl alcohol offers a safe and fun method of creating designer T-shirts that can be done by elementary school children with the guidance of adults. The activity offers an application of chemistry with art that will excite all ages-young children to seniors.
usually takes about 10 min. Once the first area has dried, another area can be done. Students may wish to experiment with circle size, dot size, and color intensity (the color can be concentrated by spotting, allowing the fabric to dry, and spotting again).
Doing Chromatographic Separations on T-shirts After seeing a presentation by Jean Buccigross a t the Joint Central-Great Lakes Regional ACS meeting in 1991 that outlined her creative method of utilizing methyl and ethyl alcohol to produce chromatographic separations on T-shirts ( I ) , a group of Fellows from the Miami University Field Center of the Institute for Chemical Education set out to find an alternative solvent and application method that would be safe and easy for use with elementary school children. The result of their work and testing with hundreds of youngsters is presented here.
Finishing the T-shirt Art Once all the chromatography patterns are developed, allow the T-shirt to dw cum~letelv.Ironing the T-shirt sets the dyes somewhat. he colbrs Gll fade 4 t h washing, but washing in cold water minimizes fading. If desired, the pattern can be made more permanent by treating it with Rit DESIGN-IT dye binder. This is a latex emulsion that prevents the dye from being washed from the fabric. Place a piece of waxed paper inside the T-shirt under the pattern. Using a foam rubber paint applicator, brush a thin layer of undiluted DESIGN-IT onto the pattern. Observe the manufacturer's precautions. After drying for one hour, heat treat the pattern with an iron following the directions on the package.
Preparing the T-shirt In advance of the activity, prewash a plain white T-shirt to remove any starch or sizing, then dry the shirt. Provide each group of students with an assortment of permanent marking pens (e.g., Sharpie, El Marko) in a variety of colors; about 100 mL of rubbing alcohol (70%by volume isopropyl alcohol); a cup or small jar for the alcohol; and medicine droppers. In addition, a wide-mouth (10-12 cm diameter minimum) container with a plastic lid such as a coffee can is needed. Cut out most of the center part of the plastic lid, leaving a 0.5-em wide ring around the outer edge. This plastic ring will be used to stretch the T-shirt fabric. Proceeding with the Plan To do the activity, place the can (with the ring removed) inside the T-shirt. Place the region of the T-shirt that is to be decorated across the open end of the can, and use the plastic ring to hold the T-shirt fabric in place. With the ring in place, pull the T-shirt fabric down the edges of the can until the fabric over the opening is taut. Place 6 6 small, concentrated dots of ink from one marker on the fabric around the circumference of an imaginary quarter-size circle a t the center of the mounted fabric. If desired, a second color marker can be used to make another set of dots between the first set. Rubbing alcohol is a ~ ~ l i at e dthe center of the circle of dots usmg a medicine hkpper or disposable plastic pipet. Slowlv suueezo the bulh so that alcohol wets the fabric and move: in-a radial fashion to the edges of the mounted fabric creating a characteristic chromatographic separation that looks much like a flower. When the pattern reaches the desired size (but no larger than the hole in the plastic lid), stop adding alcohol. Allow the fabric to dry. Drying
Caution Use the iron carefully, and be sure to test the iron temperature on an old T-shirt to prevent scorching.
Creating a Flower Pattern A second application of radial chromatography appropriate for elementam students uses water soluble markers ,such as those used for writing on an ove~hcadprojector^ and water as the solvent ( 2 , .The novelts of this techniaue is the unique flower-like patterns that result (see ~ i ~ . ~ l ) . Get a piece of round filter paper and poke a small hole in the center. With one marker, equally space 5 to 6 dots about the circumference of a small circle about 6-8 mm from the center bole. Select a different wlor pen and use it to place dots in between the first set of dots. You will end up with a circle of 10-12 dots around the center hole. From another piece of filter paper, cut out a small piece in a wedge shape (a triangle 4 cm tall and 2 cm a t its base); fold or roll it into a cone. Place the pointed end of the cone into the hole of the dotted piece of filter paper; the cone will serve as a wick. Fill a plastic cup with water to within 1cm of the top. Dry the rim of the cup with a paper towel then place the spotted piece of filter paper across the cup rim so the cone is in contact with the water. Water travels up the cone to the filter paper wetting the paper in a circular pattern. As water passes the ink spots, the radial chromatography pattern begins to develop. Let the pattern develop until the water spreads to about 1cm from the edge of the filter paper. This takes from 5-10 min, depending on the
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Figure 2. Developing chamber for larger pieces of filterpaper.
Figure 1. An example of the flower designs that can be produced by radial chromatography diameter of the filter paper. Remove the filter paper and allow it to dry. Using a Developing Chamber
Large pieces of filter paper, e.g., 24 cm, require a developing chamber that can be made from a disposable aluminum pan with a clear, plastic lid such as a frozen pie container (see Fig. 2). Cut the plastic cup that holds the water to the height of the aluminum pan. The filter paper will be supported in the middle by the cup and on the edges by the aluminum pan. Spot the filter paper as before. Use more
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ink for each spot either by making the spots larger or by spotting the same position several times, allowing the spot to dry before adding more ink. Insert the cone into the spotted piece of filter paper. Dry the edges of the pan and the cup, then lay the fdter paper so the cone is in wntact with the water in the cup and the edges of the fdter paper are supported by the aluminum pan. Rest the clear wver over the filter paper. Allow about an hour to develop the chromatogram. After the chromatogram is complete, remove the filter paper and allow it to dry. Enhancing a Love for Chemistry
These procedures are interesting for students, and the atmosphere created enhances chemistry as a student's welcome companion in creative activities. Literature Cited 1. Bueeigmss, J. M.J. C b m Edue. 1983, in press. 2. S a w i s , M.;%"is. J. L.Fun with CbmlatwA Guidebooi ofK-12Actiuities Iblume 2: Institute for Chemical Edueatbn. University of Wiseonain: Mediaon. WI, 1992.
