Remarking on oil paint materials. I've had oil #paint take 8 weeks to dry... in a thin layer on the canvas.
I think I used slow drying pigment (ultramarine purple in Walnut oil) and added, foolishly, slow drying oil- safflower I think.
that was very annoying to wait for.
I've since used linseed as my additive almost exclusively. Occasionally I'll pull in an alkyd to drive speed drying, but I really prefer not to do that. it's easier to manage drying rates without alkyds imo.