About 12 years ago I tried water soluble oils as suggested by Rain for being easier to use on outdoor excursions. One of the disadvantages was grainy results when diluted for transparent watercolor effects. Now there is a medium that can be mixed for glazing. The above painting illustrates another limitation. Thick paint develops a skim dry to the touch but remains liquid underneath for years. Just last year finally this painting dried and did not smell like fresh oil paint. Unfortunately I like to combine thin washes and thick paint. But I should never the less try water soluble oil paints again.