How is ester gum made?

Ester gum is produced by the polymerization of rosin acids, which are derived from natural sources like pine resin. The process involves heating these rosin acids with glycerol or other polyols, often in the presence of catalysts, to form a viscous, thermoplastic resin. This resin is then cooled and can be further processed or modified for various applications, such as in inks, coatings, and adhesives. The resulting ester gum is valued for its adhesive properties and stability.