Op art - like Henrique Matos

You need:

1. white drawing sheet A4 size
2. liquid water colour
3. jar with water
4. compasses
5. ruler
6. pencil
7. black waterproof markers

Henrique José Teixeira Matos is a Portugese painter. He is born in 1961 in Oporto.  Matos painted landscapes, portraits and abstract works, but is best known for his op-art work.
Show pictures of Matos's work on Wikimedia Commons. Look especially the op-art works and discuss what you see.

More op-art lessons on this blog can be seen following the link Op-art.

Paint a white sheet of paper with liquid watercolour and a lot of water a plain background.

Drip some liquid water colour on the surface while it is still wet. Use more water if the colours won't flow. Leave the sheet to dry.

Use compasses to draw some small circles (2 cm average) on the sheet. Draw wider circkels around them. Fill the sheet with those circles and half ones near the edges.

Draw lines from the middle of the circles to the edges. Be sure it's an even number of lines and  Kkeep the lines as much as possible equidistant from each other. Color the squares alternating with a black marker or pencil.