I used acrylic paints. This exercise was a trickier than I first anticipated but my technique improved a little with practice. I had to be careful to keep the brush clean for the next ‘layer’ of diluted colour. It was easier to blend the layers together as more water was added and the paint became more transparent – for the lighter end of the spectrum I just used the lightly coloured water from my water jar. When very wet, the acrylics behave like water colours and blend and merge readily – there is some loss of control but I enjoy that. I found that working wet on wet the second colour merged more readily with the first.