Crackle Glaze can be used in between any 2 contrasting Fresco Chalks. The chemical reaction of paint drying on top of the glaze layer is what makes the cracks happen. Apply a coat of Fresco Finish, dry it. Scrape over (with splodger/ Spatula/ palette knife) a thin layer of Crackle Glaze. Dry it (you can use a heat tool). Apply a generous second colour of Fresco Finish Chalk Acrylic with short single strokes and watch it crack in minutes! Easy clean up in warm water. Low or no VOC's. Eco Friendly.