The shellac coatings were prepared
by dissolving dewaxed and bleached shellac (5 %) in
alkaline aqueous medium (0.6 % ammonia) at 95 C. To
this, PVA (binding and coating agent) (3 %) previously
dissolved in hot water was added along with triethanolamine
(surfactant) (1 %) and 0.1 % oleic acid (lubricant,
binder and defoaming agent).