[Tito Champena]

Thank you Tim, thank you Michael.

You're both right, I'm not using oil for the underpainting and therefore the paint dries flat. Retouch varnish or medium seem to bring back the original value. I suppose retouch varnish is preferable over medium in order to follow the "fat over lean" principle. However, when I spray retouch varnish, the varnish layer looks spotty and if I try to make it even, then it runs with the paint because it's too much.