Achieving Volume and Airiness using the UNLIMITED Palette | Demonstration by Kristine Onsrud 

You use solvents like white spirit only to clean your brush. Solvents are not used to thin down your oil paint in classical techniques. You use linseed oil for that. If you want your linseed oil to be more runny - you can add small amount of white spirit in the mix (or walnut oil). You can also use pure walnut oil if you want your paint to be extra runny - but walnut oil cure VERY slow (you may need to add sicative to help with that) and doesn't make that strong connection with the paint (just to be aware). You can use white spirit if your technique is impressionistic and experimental of course. Toulouse Lautrec famously were painting almost aquarelle with oil and solvent. The finished look will be dull and mat by design. If you use professional series paint you don't need that much linseed oil too. Try using as little as possible as a test. The ground/canvas have enormous importance here. If your ground is very absorbent and ill isolated - you will have hard time to achieve runny paint. I recommend preparing the ground with oil primer. Acrylic gesso gives more absorbent ground. You should sand the surface obviously. Using fingers have nothing to do with the use of solvent or not. It's simply a form of brush. I have not seen people to use sandpaper while the paint is fresh (but I am not very familiar with the technique). The sandpaper technique is used to subtract the upper paint layer and to introduce some tonal/structural effect.

titanium white

Flake White Hue

@@flaviop.4079 thanks for the info mate! appreciate

it's how it works when you learn under an artist. you typically learn their style as a way to develop drawing/painting skills and then your own style will develop as a matter of course.

@@skrewler This is usually only possible in very few cases! If the teacher, in this case Nerdrum, is so incredibly dominant and also incredibly ideological, then that's what you get. Pure imitators!