NATURAL RESINS

**Definition:** This place covers:

Natural resins, French polish, drying-oils, driers or turpentine per se.

Obtaining, purification, or chemical modification of natural resins, e.g. oleo-resins.

Obtaining spirits of turpentine.

Obtaining drying-oils.

Chemical modification of drying oils, e.g. oxidising, voltolising; Apparatus therefor.

Compounds to be used as driers (siccatives).

Preparation of French polish.

**Glossary:** - Drying-oil: Unsaturated fatty oil, such as linseed oil, tung oil, poppy seed oil, perilla oil and walnut oil, that becomes hard, tough and elastic upon exposure to the air when spread into a thin film. - French polishing: Wood finishing technique for wooden furniture that results in a very high gloss, deep colour and tough surface; it consists of applying many thin coats of shellac using a rubbing pad. - Natural resin: A resin of natural origin, being obtained, except for shellac and natural rubber, from the secretions of certain trees, which exude the resin when the bark is wounded. The initial liquid exuding from a wounded tree is an oleoresin containing the natural resin plus some oils. - Shellac: A natural resin of animal origin produced by refining the secretion of the shell louse. The resin consists of a complex mixture of esters mostly based on aleuritic acid. - Siccative: Drying agent; a substance that promotes drying, e.g. linseed or flax seed oil. - Turpentine: Resinous exudate or extract obtained from coniferous trees, particularly those of the genus Pinus. The main components of turpentines are mono and bicyclic monoterpenes - Voltolising: Subjecting oils to treatment with an electric discharge.