Liquid white is essential to the wet-on-wet painting technique. You coat the canvas with a base coat of the liquid white and then paint over that. Oil paints are thick and have a consistency of soft butter, but liquid white is more of a creamy paint. The creaminess of the liquid white allows it to be painted on the canvas in even and smooth strokes. Bob Ross's liquid white is a secret combination of ingredients exclusive to the Bob Ross Inc. Liquid white is only usable with oil painting and other variations of the base coat medium are available, like liquid clear, liquid black and liquid opal.