A red silk is different from a red chalk. An oil painting is different from a tempera painting.

It is the nature of the surface, smooth or rough that determines changes in colour.

If surface is smooth, it will reflect light and color will be more brilliant.

If surface is rough, colour looks opaque and smooth.

But a black velvet is much more black than any other black velvet,

Because velvet is neither smooth or raugh.

Velvet is velvety.

​

Cit. Bruno Munari, Italian designer