It’s Sort of Like Watercolor
Gouache is a paint that is similar to watercolor. What makes it different from watercolor is that it can sustain greater value. In other words, you can paint more layers of gouache to get darker shades of a color.
Since it is a water-color type paint, it’s used on heavier paper. It works really well on watercolor paper, but bond paper also works.
What can it do?
Today was the first time I had used gouache, so I’m still learning what kind of paintings this media is good for producing. Since it is paint, it’s good for fluid drawings. In my art studio class, we’re using it to study line and line quality. It’s good for that because the lines that gouache painting creates have a nice natural variation. Also, gouache works well in layers, so you can paint a line several times.
One thing I noticed while painting in gouache was that you have to be careful to let layers of paint dry before going over them again. If you go over a line too soon, to say, make it darker, you can accidentally get splotches of spreading paint.