Making my own oil paint
Late last night I experimented with grinding my own oil paint. I've been trying to replicate the effects of pre-Modern painters. They don't show brush strokes; the paint is flat, almost enamel-like, and great detail is possible.
I've found that tubed paint usually is mostly good for pure detail work, but too hard to move to get coverage. Adding oil loosens it up for coverage, but issues with controllability start coming out to play (the looser it is, the runnier). And it takes a fair amount of typical oil added to remove brush strokes from the equation.
Other oil preparations exist: sun oils, stand oils, thinners, sila-based gels. Stand oil is particularly useful I've found, but is often too viscous to do the job quite right.
So.... My usual mix is tubed paint + 1 drop stand oil + 1 drop linseed or walnut; this gets a loose but viscous paint. This is close to the goal, but is a bit on the loose & long side.
The experiment I'm running now is pigment ground in pure stand oil: it's highly viscous, doesn't retain brushmarks, and can be loosened as needed with additives. Experiment one is is how yellowing it will be vs a few other oil types. Experiment two is how well it can be put in tubes. :-)