Hard / hardness: black 43%, blue 15%, silver 12%, …
Heller E. (1989)

Black and white are the most extreme examples of heavy and lightweight colours. The movement is in the height. Heavy colours, when applied above the viewer, tend to press down. Because of their heaviness, the weight is literally felt. A black ceiling will be estimated lower than a white one. Heavy is also connected to hard and large, while lightweight is felt rather fine, small and soft (Osgood, 1957). If colours have the same intensity such as red and green, red will outweigh green. (Meerwein, 2007)

Osgood’s Research (1957) made a significant correlation between heavy and hard with big, while lightweight is sensed rather fine and small. “Now we know, from our factor analytic work, that up, small, light-weight and white tend to go together in meaning and metaphor as opposed to down, large, heavy, and black.”

Rooms painted black appear much smaller than white ones. Black furniture dominates the space. In the most positive case they appear representative, in the most negative case they are oppressive. A black sofa appears to be harder than a white one. Colours influence the impression one gets of size, weight and material. Boxes with a light colour will be assessed less heavily than dark ones. The impression of the weight is not only due to the colour. The material usually gives the deciding factor. Every effect is the sum of all experiences.
(Heller, 1989)