Yesterday I tried something new ( particularly for myself). I decided to do underpainting of gouache for myOPs. I used Caran D'ache Gouache 8 colors set for underpaiting of Grand Canyon and then pained with OPs over it.
I wasn't impressed when I tryed to put next layer of Sennleirs over my painting. It just wouldn't go down, how I wanted to see and feel it. So I stuck with Neoplastels 24 colors set from Caran D'Ache and just a few extra Senneliers (Orange and colorless blender). I finished my study of Grand Canyon with most accent given to the tree on a front of painting and paid very little attention to mountains on background, just trying to keep up with their color.
More likely I'll be back to the same theme few weeks later, after I'll finish two other painting I'm working with right now. Generally I would say that combination of Gouache with Neopastel was very successful, while my try to combine it with Senneiler wasn't up to my expectations. Senneliers did a good job over Neopastels, but not with underpainting itself.