Ramblings on watercolor and gouache
It's confusing to watercolor painters to learn that some pigments in transparent watercolor are highly opaque, for example, the cadmiums, cerulean blue and chromium oxide green. These pigments are naturally opaque, so they have more covering power than most watercolor paints. But they aren't as dense as gouache. Gouache has additives that make the paint more dense and opaque.
A gouache painting looks more like an oil or acrylic than a watercolor, although it's possible to make a watercolor that looks like gouache simply by using less water and more paint. The concern with either method is that thick paint may crack or break off the surface, which is one reason a more rigid support is needed, such as heavy illustration or watercolor board.
Transparent watercolor as a pure medium takes a lot of abuse these days from artists doing mixed watermedia and gouache. They claim watercolor's old-hat and everything has already been "done" in the medium. I don't agree with that. I love the splash and spatter of watercolor and the texture of the paper, the richness of a fine wash. There's nothing, absolutely nothing, as fine as a pure watercolor masterfully painted. I'm disappointed when I go to big watercolor shows and find most of the paintings appear to be acrylics or opaque watercolor. I can remember when the best artists in the country painted pure transparent watercolors and they were amazing.
I'm going to try some gouache, because I really haven't given it a fair trial yet. But I can't see myself giving up my watercolors.