Lighten and Darken Colours
The colours of the Albrecht Dürer artists’ watercolour marker can be gradually lightened. The amount of water decides the degree of lightening.
As for darkening a colour, not just black or grey can be used, but also the respective complementary colour.
Complementary colours are opposite each other on the colour wheel. The layering of complementary colours creates broken or grey colour mixtures.
Complementary colours put next to each other enhance each other’s colour effect. So, for example, orange makes blue shine when placed next to it.