Tonal Progression

Progressing from white to black, I required an increasingly larger amount of black pigment to achieve the next tone

Neutral grey

Neutral grey adjacent white

The grey appears darker next to the white

Neutral grey adjacent black

The grey appears lighter next to the black

In both instances

It seems grey is more than a mixture of black and white but also contains hues of red, yellow in blue, which were less obvious when it was adjacent other grey tones.