Kids, how can you use chromatography to create your own colorful T-shirt design?  In this activity, you will separate the ink from permanent colored markers to make a rainbow of colors on your T-shirt!  Chromatography is a technique used to separate mixtures and can be used by chemists in fields as diverse as environmental studies to detect pollution in water and air to crime laboratories to identify clues such as blood, ink, or other substances found at a crime scene. 

Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.

What do you do?  First, review the information in the background section provided in the reference link below.  You will need a coffee can, coffee filter or paper towel, a pre-washed t-shirt, permanent markers, rubbing alcohol, eye droppers, and a rubber band.  Before you make a chromatogram on your T-shirt, practice with a coffee filter or paper towel.  Rubber band the coffee filter or paper towel over the coffee can and draw a circle of colored dots on the coffee filter or paper towel.  Using the eye dropper place a few drops of alcohol into the middle of the circle. As the alcohol spreads, watch the pattern the ink makes.  The more alcohol you use, the farther the ink spreads; using less alcohol prevents the ink from spreading very far.  Try any design you like, although the circle works best (a dotted circle forms a flower pattern). Repeat using your T-shirt instead of paper.  Be sure that only one layer of the T-shirt (the back or front) is laid over the coffee can at one time.  Let your T-shirt dry. Have a good time!

What’s going on here?  Chromatography is a process used to separate mixtures. A substance is placed onto or into a medium and a solvent is passed through the test substance.  In chromatography science, the solvent is called "the mobile phase" and the medium is called "the stationary phase".  In this experiment, the medium is coffee filter paper or the t-shirt, the solvent is alcohol and our test substance is ink.  Ink is a mixture; it is made of different substances mixed together.  Parts of the test substance (the ink) may be attracted to the solvent (alcohol) and follow it up the medium (the coffee filter paper).

Have you ever mixed paint, crayons or food dye colors to create new colors?  How do you make the color orange?  Remember that yellow, red and blue are primary colors (they are not created by combining other colors).  As you study the chromatographs and separate the ink colors, keep this information in mind.  What do you think a chromatogram of orange or brown ink will look like, and does the result match your guess? 

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Kathleen Carrado Gregar, PhD, Argonne National Labs 
[email protected]
October 2005

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Reference:  www.swe.org/iac/LP/tshirt_02.html (SWE is the Society of Women Engineers).
Finished T-Shirt example from the SWE page.