Exercise 2, Primary and Secondary Colour Mixing

Eventually I found information on how to obtain pure primaries, not before I'd made a long search and getting quite confused in the process. The most straightforward common sense information I discovered to my relief in Ian Sidaway's Colour Mixing Bible.
To locate the most intense hues it was a case of eliminating any trace of other primaries in the hues of colours: out of the yellows mixed I found the most intense to be the primary yellow, which I mixed by combining cadmium yellow and lemon yellow. Incidentally, chrome yellow was the most opaque. Equal quantities of the following mixes made up the primaries:
From the reds: cadmium and alizarin crimson, or cad red deep - which appeared the same as the first two reds (when mixed).
The blues: ultramarine and pthallo blue.
To obtain pure primaries I found that these hues need to be an equal combination of warm and cool.
ie. cad red - warm bias towards yellow
alizarin crimson - cool bias towards blue.
pthallo blue - cool towards yellow
ultramarine blue - warm towards red.
cad yell - warm towards red
lemon yell - cool towards blue.

For the secondaries -  equal amounts of cad red and ultramarine produce a greyish violet, but alizarin crimson and ultramarine: the result is an intense violet.
Primary yellow - lemon and cadmium look transparent against grey ground giving them a light grey tinge.
Around the centre of the scales yellow to blue and red to blue it is hard to discern much difference between the values. I added white to the darker colours - blue and red, to  maintain consistent tonal value along them.
From yellow to red maintaining an even tone was tricky - from the middle to red tones become more rose pink or salmon in tone rather than dark oranges - due to the addition of white.
Yellow to blue - when I half close my eyes I can see that the second colour value is lighter than the first as there's a grey shadow beneath the first due to white being mixed in, causing a darker appearance. In a couple of greens around the centre it's perhaps not immediately apparent, but I think the second and eighth values are much lighter in tone than the others, including the first yellow.

Mixing primaries: yellow to red, yellow to blue, red to blue

Mixing hues to achieve violet

Maintaining consistent tonal value by adding white