Wet in wet is the queen of watercolor painting. The reason is that when we paint wet paint into thoroughly wet watercolor paper, the particles of pigment settle out into the little hills and valleys of the paper. This "sedimentation" is what makes watercolor washes so gorgeous. The paint diffuses into the surrounding areas depending on how wet each area is. This gives us the ability to paint soft, slightly out of focus pictures. The technique of wet in wet produces lovely, tranquil works; but they remain visually exciting both from a distance as well as very close up.
The trick to getting this effect is in the paint selection. We select paints for their sedimentary properties. By this we mean the properties of the pigment particles. Some are very light. The light ones do not settle easily and so "migrate" from where they are put and give us the soft, diffuse look. The heavy ones tend to clump, or settle, or both. This "aggregation" of the heavy particles sink into the papers valleys. Every color acts a little differently so the effect is continually changing thereabout the painting. You cannot ask for a lovelier technique.
Wet in wet of this type is not for the beginner, even though many people come to watercolor for just this reason. You need time to get used to your paints and how they feel. You might want to start with my palette, (paint selection), its well thought out.
You might also want to see three of my beginner materials lessons, paint, paper, stretching paper, to better understand what I am doing in this lesson and why.
The colors in this demonstration are the yellow - purple complementary color scheme, with yellow predominating. There are green notes added in a few places. The composition is entirely curvilinear. The negative space is subordinated (smaller) to the positive (larger).
The map shows the location of each of the paints. The group on the left are the sedimentary colors. Those in the right are the non sedimentary colors. The palette is just a cut down ice cube tray.
...( sedimentary )
0 - Red
1 - Yellow
2 - Green
3 - Blue
...( non sed. )
4 - Cool Blue
5 - Warm Blue
6 - Warm Red
7 - Cool Red
8 - Warm Yellow
9 - Cool Yellow