Chromatography is a technique for separating coloured chemicals. The colour inks in each of your felt tip pens is probably made of a mixture of different colours. Here is a very simple experiment that you can do at home in your kitchen. Have a look at the animation and then read the instructions underneath.

You will not have any special chromatography paper at home, but you can use blotting paper of some kitchen towel. Cut a piece about 10 to 15 cms long and 4 or 5 cms wide.

Put about 2 cms water in the bottom of a tall drinking glass. If your felt tip pens are permanent you will have to use gin or vodka instead of water. If your felt tips are washable then it will work with water.

Draw a thin pencil line about 2 cms from the bottom of the piece of paper and mark some little crosses on the line.

Make a little coloured dot on top of each cross with a different coloured pen.

Hang the paper in the glass so that it just dips into the water. Make sure that the water does not cover the coloured dots.

After a bit a little while you should see the water soaking up the paper. Watch what happens.

When the water has reached the top, take it out. Mark the top of the water with a pencil line and leave it to dry. The mark each coloured spot with a pencil ine at the top.

Congratulations: you have made your first chromatogram.

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