Nunn Design® Glue is silicon based, not water based and prevents moisture from absorbing into the image. We found that when an image absorbs moisture, bubbles can form in the finishing glaze. When applying Nunn Design Glue, coat the backside of the image thinly and evenly. Rinse brush with water. Project Uses: Adheres strongly to plastic, metal, glass, wood, and paper. Multiple layers remain crystal clear.