We are asked to create a tonal anachromatic scale. The instructions call for us to work in narrow lines from white through the faintest greys to darker greys until the darkest tone is black from the tube. After we have done this exercise, we are asked to study the scale and find the tone that is equidistant between black and white (neutral grey) and to apply the grey to two scraps of paper. We are told to place the scraps of paper at either end of the scale and make notes on the quality of the grey – do they look the same? After doing this exercise, we are asked to prepare a neutral grey ground for the next primary and secondary colour mixing exercise.
I have done this exercise in a slightly different way, as I studied tonal scales separately some time back and I found the best way for me to do it was to draw a set of boxes all the same size and place black at one end and white at the other and then to find the midtone before filling in the rest of the boxes. I find this works easier for me, I don’t know why. I decided to do this test using acrylic paints in my small A5 sketchbook.

The photo was taken in artificial light and seems to make the colours on the lighter end of the grey scale appear brown but they are not in natural light. The slips of paper are placed on either end of the scale in the bottom example in the photo above. It is quite clear to see that the grey appears stronger when placed next to the white.
I then tried the exercise with my Cobra water-mixable oils.

I used the same technique – i.e. placing white at one end and black at the other and then working with the brush to get the neutral grey. I’d used a knife to lay down the white. Again the grey looks way more intense next to the white.
The more I use these Cobra paints, the more I am loving them. I didn’t use water for this exercise to thin them down, I just manipulated the pigments (blended the paint itself) to get the different tones, which was not always easy with a brush.