Merana Grinding Oil, 0.5 Pint. Merana Oil is a proprietary formula and is an excellent "open medium". It is typically used to mix with powdered paints and allows them to be stored on your palette or in closed jars for long term storage. The Merana Oil will not dry and has the added benefit of retarding dust. It is also used as a painting medium for artists who like an "open medium" with unlimited working time. California residents see Prop 65 Warnings