We cut strips of blotting paper just wide enough to fit into plastic cups.
Next we made blobs of colour with different markers on the paper approximately 5 cm from the bottom. We put some water into the cups so that it was just below the blobs on the blotting paper. Then we waited.
What did the water do? It slowly soaked up through the blotting paper and the blobs of colour.
What happened to the colours? The colours started to spread with the water and we saw some of the different colours that make them up.
Why did this happen? Inks and dyes are made from different chemicals. To make all the different colours, lots of different coloured chemicals are mixed together. As the water rose up the blotting paper, it dissolved the chemicals and carried them with it. The different chemicals separated out.
Separating chemicals like this is called Chromatography.
