Before turpentine was widely used, artists used 100% rosemary or spike oil of lavender essential oils to thin their paints and to make "Imprimatura" washes. These two essential oils are perfect for creating a wash, they evaporate within seconds, creating a very "lean" paint layer, perfect for painting over with subsequent layers of oil paint. Most artists could not afford the high expense of essential oil over the last few hundred years, so they used turpentine as a cheap substitute. Modern technology has made essential oils very affordable and eco-friendly.