When you need oil paint to create an effect you cannot otherwise achieve with paint alone, oil paint mediums can modify the paint to achieve those effects. Drying time and viscosity vary between colors — even from the same range or brand. Oil paint mediums can increase or decrease drying time and viscosity. Each medium has unique properties — so different effects can be achieved depending on which medium you mix into your paint. You can thicken paint, thin paint, give it a matte or gloss finish, soften the paint, level out the brush strokes, or give your paint more body and texture.