Foliage Fun: KidsZone →

Hidden Colors

Activity: Using Paper, Leaves & Markers

by Sue Stoessel

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This technique is often used in Crime Labs to analyze materials!

You will need:
Variety of water-soluble felt-tip black pens (Sanford's "Mr. Sketch" works nicely)
Plastic or paper cups
Strips of paper towel or coffee filter paper, cut to height of cup
Pencils
Tape
Water

How to do it:
1. Tape one end of paper strip to pencil as shown in drawing.
2. Draw a line with marker an inch or two from the bottom of the strip.
3. Balance pencil on top of cup so that paper strip hangs inside.
4. Carefully trickle water into cup so that it touches the paper below the marker line.

Watch over the next 15-45 minutes as *capillary action draws the water up through the marker line and separates out the hidden pigments. Heavier pigments separate out first, lighter ones will separate out further up the piece of paper.

Questions to ask:
How many colors are revealed?
Are they the same for every marker?
Do they appear at the same place on the paper every time?
What happens with a permanent marker?

*Capillary action is described as the tendency of liquids to move through small tubes and airlike openings that are found in porous materials. This happens because the molecules of the liquids are more attracted to the walls of the openings than to each other.

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KidsZone Drawing Contest: For kids 13 and under, send an original drawing of foliage by November 10. Get details now!

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Hidden Colors, Part Two

Chromatography may be done with leaves, under adult supervision, since alcohol -- either isopropyl or ethanol -- is used instead of water. Try different leaves at different times of the year, or flower petals, to find their hidden colors, too!

See set-up for Chromatography with Markers, with these modifications:

1. Use a glass container, since containers made of other materials may react with the alcohol.

2. No markers. The colors we are interested in will come from the leaves.

3. Grind or snip leaves into small pieces and cover with alcohol. Dip edge of fresh paper strip in the alcohol/leaf liquid and set up chromatography as on previous page.

4. This chromatography will have to sit overnight, in a spot away from flames or heat!

After 12-18 hours different bands of green chlorophyll will be revealed on the paper. In some leaves, especially those collected in the fall, bands of yellow, orange, and red will be visible as well.

These activities were developed by Sue Stoessel, senior education associate at the Museum of Science, Boston. One of the world's largest science centers, the Museum of Science takes a hands-on approach to science, attracting approximately 1.5 million visitors a year through its vibrant programs and over 700 interactive exhibits.