Capillary action: colour bleed

by Mar-Jo Angelico
(Australia)

Paper towel

This experiment shows how water is absorbed in paper.

Take a paper towel or serviette, and a bowl half full of water. Cut the paper towel into strips about an inch wide and six inches long (3cm x 15cm).

First, just hang one strip of paper towel over the edge of the bowl, such that the bottom of the strip is in the water and the rest is not. Point out how the paper towel is wet above the water level, even though it wasn't dipped in.

Then, take a texta (felt-tip pen), parcel marker, or similar, and make a dot on a strip of paper towel. Position the dot such that when you hang the strip in the bowl as before, the dot will be about an inch ABOVE the water level. (If you like, put a dot on the end of the strip that stays dry, too. This is for comparison later.)

Put the strip of paper towel in the water as before, and leave it for a couple of hours. The colour will run upwards, and also separate into its component colours. (Some black parcel markers are quite interesting in components.)

I learned this experiment from my mother, Mar-Jo Angelico.

Gabrielle Angelico