Abietic acid

Abietic acid (also known as abietinic acid or sylvic acid) is an organic compound that occurs widely in trees. It is the primary component of resin acid, is the primary irritant in pine wood and resin, isolated from rosin (via isomerization) and is the most abundant of several closely related organic acids that constitute most of rosin, the solid portion of the oleoresin of coniferous trees. Its ester or salt is called an abietate

Rosin has been used for centuries for caulking ships. It is also rubbed on the bows of musical instruments to make them less slippery. In modern times methods have been developed for improving the properties of the rosin acids, which are otherwise soft, tacky, and low-melting and subject to rapid deterioration by oxidation in air. Stability is greatly increased by heat treatment.

Resin acids are converted into ester gum by reaction with controlled amounts of glycerol or other polyhydric alcohols. Ester gum has drying properties and is used in paints, varnishes, and lacquers.