Orange flake shellac used for a wide range of application as an adhesive , and sealant.  In jewelry applications used by simply applying heat to the shellac and melting it to hold components while setting stones, chasing or engraving.  

Once the shellac cools off it hardens and won’t break down.  It is easy to use with a heat source (like an alcohol lamp), it sets up fast and holds, item can be adjusted into position by simply reheating the shellac.