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13.01 ‑ Lac; natural gums, resins, gum-resins and oleoresins (for example, balsams).
(Ⅰ) Lac.
Lac is a resinous substance produced on several kinds of tropical trees by an insect belonging to the same family as the cochineal and the kermes.
The most important commercial varieties are the following : (A) Stick lac, usually consisting of twigs on which the lac has been deposited in a more or less thick layer; it is dark red and the most highly coloured variety of lac. (B) Seed lac, the crushed lac detached from the branches, usually by washing which removes part of its colouring matter. (C) Shellac, also known as sheet, plate, or slab‑lac, obtained by fusion and filtering which purifies the gum. It takes the form of thin, vitreous flakes, amber‑coloured or reddish. A similar product in the shape of discs is known as "button lac".
Shellac is used largely in the preparation of varnishes, in the electrical industry and for the production of sealing wax. (D) Refuse lac (or garnet lac) obtained from the residues left from the preparation of shellac.
Lac may also be decolourised or bleached and is then sometimes put up in the form of twisted hanks.
The sap of certain oriental trees which hardens, forming a resistant film when exposed to air (known as "Japan lacquer", "Chinese lacquer", etc.), is excluded (heading 13.02). (Ⅱ) Natural gums, resins, gum-resins and oleoresins.
Natural gums, resins, gum-resins and oleoresins are vegetable secretions, which may solidify on contact with air. These terms are often used indiscriminately. These products have the following distinguishing features : (A) True gums are odourless, tasteless and more or less soluble in water, forming sticky substances. They burn without melting and without odour. (B) Resins are insoluble in water, have a slight odour, are poor conductors of electricity and acquire a negative electric charge. They soften and melt more or less completely on the application of heat, and when ignited burn with a smoky flame and characteristic odour. (C) Gum‑resins, as the name implies, consist of natural mixtures of gums and resins in variable proportions, and are therefore partly soluble in water; they generally have a penetrating and characteristic odour and taste. (D) Oleoresins are exudates consisting mainly of volatile and resinous constituents. Balsams are oleoresins characterized by a high content of benzoic or cinnamic compounds.
The principal products are : (1) Gum Arabic (from various acacias) (sometimes also called Nile gum, Aden gum, Senegal gum); gum tragacanth (obtained from certain varieties of Astragalus); Basra gum; Anacardium (gum of the cashew nut tree); Indian gum; certain so‑called "indigenous" gums from various species of Rosaceae, such as cherry, plum, apricot, peach or almond trees. (2) Fresh oleoresins (liquids) of the pine (including turpentine), fir or other conifers (crude or refined), as well as conifer resins (galipot, etc.) which are dried on the incision on the tree and which contain vegetable waste. (3) Copal (India, Brazil, Congo, etc.), including fossil copal; kauri gum; damar; mastic; elemi; sandarac; dragon's blood. (4) Gamboge; gum ammoniac; asafoetida; scammony; euphorbia; galbanum; opoponax; olibanum or incense; myrrh; acaroid; guaiacum. (5) Gum benzoin; styrax or storax (solid or liquid); tolu balsam; Peruvian balsam; Canada balsam; copaiba balsam; Mecca balsam; thapsia. (6) Cannabis resin (crude or purified) obtained from the Cannabis plant. (Cannabis resin is a narcotic drug see the list at the end of Chapter 29.)
The natural gums, resins, gum‑resins and oleoresins covered by this heading may be crude, washed, purified, bleached, crushed or powdered. They are, however, excluded from this heading when they have been subjected to processes such as treatment with water under pressure, treatment with mineral acids or heat‑treatment; for example : gums and gum‑resins rendered water‑soluble by treatment with water under pressure (heading 13.02), gums rendered soluble by treatment with sulphuric acid (heading 35.06), and resins which have been heat‑treated to make them soluble in drying oils (heading 38.06).
The heading also excludes :(a) Amber (heading 25.30). (b) Medicaments containing natural balsams and prepared medicaments of various kinds known as balsams (heading 30.03 or 30.04). (c) Lac‑dye, the colouring matter extracted from lac (heading 32.03). (d) Resinoids (extracted from the substances of this heading) and extracted oleoresins (heading 33.01). (e) Tall oil (sometimes known as "liquid rosin") (heading 38.03). (f) Spirits of turpentine (heading 38.05). (g) Rosin, resin acids, rosin spirit and rosin oils, resinates, rosin pitch, brewers' pitch and similar preparations based on rosin (Chapter 38).
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