Why are some so-called “transparent” watercolors actually opaque?
A. It’s the nature of certain pigments, such as cerulean blue, the cadmium colors, and some of the earth colors to be denser and more opaque than others. This is also true in other paints than watercolors, with the exception of gouache, which has opaque matter added to the pigment to give it covering power. Watercolors are traditionally called “transparent” because they are diluted more than other paints and applied in a fluid manner so the support, usually white paper, will reflect through the paint layer. Other media are generally applied more heavily so the paint layer has more body and covers up the support, even though the pigment itself may be somewhat transparent. These pigments are frequently used by oil and acrylic painters for glazing. However, regardless of the nature of the pigment, brands may differ greatly both in hue and transparency because of different manufacturing processes. For instructions on testing your paints for transparency, see my project, Testing Paints for
