Duncan Overglazes - OA 901 - Essence - 1/2 Ounce Bottle Capture the essence of good brush and tool hygiene with Essence. The must-have solution for cleaning all of your brushes and tools used with overglazes. Essence is the perfect accessory to working with Duncan overglazes; other cleaning agents may contain water or solvents, resulting in the separation of overglaze during subsequent applications. Use a separate bottle of Essence for each overglaze product. Made in USA.