Exercise Drawing on a coloured ground

I am experimenting with different coloured grounds here initial on coloured card and then on paper covered with and acrylic wash.

Face studies, watercolour on coloured cards for me, here the  blue  ground is the blue ground works the best.

Studies of Cyclamen plant,  watercolour on card

Here I felt the yellow and green grounds worked well, so  I used a olive green acrylic as the ground for a further plant study

Testing how the watercolour took to the acrylic ground in my sketch book. The acrylic attacks as waterproof film across the paper, so the watercolour is not absorbed and sits, taking a long time to dry, on the acrylic.

Final Study, the watercolour is appears more opaque on the acrylic ground looking at the study it would be possible believe it was done all in a acrylics. One nice feature of the painting of on the acrylic ground is being able to mix the watercolour on the surface of the painting, able drop dark tones in to the pools of red watercolours when painting the plants petals.