A lot of work goesinto these clooudservations as they require the previous layers of paint to dry to get the effects I'm seeking. I started off with 2 shades of cad yellow- light and medium. This went on the cloud portions that will layer be mostly white. After those had throughly dried I added the blues and purples with a substantial amount of titanium white. I let that dry and started to add the areas of white in the white cloud parts. So far I've added one layer of zinc (aka mixing) white and will add a bunch more and alter the blues a tad.